Cisco NX-OS

Overview

Cisco NX-OS is a network operating system for Cisco Nexus-series switches.

Warning

This format is still in beta, please use it wisely.

Related Built-in Rules

Benefit from SEKOIA.IO built-in rules and upgrade Cisco NX-OS [BETA] with the following detection capabilities out-of-the-box.

SEKOIA.IO x Cisco NX-OS [BETA] on ATT&CK Navigator

AdFind Usage

Detects the usage of the AdFind tool. AdFind.exe is a free tool that extracts information from Active Directory. Wizard Spider (Bazar, TrickBot, Ryuk), FIN6 and MAZE operators have used AdFind.exe to collect information about Active Directory organizational units and trust objects

• Effort: elementary

Add User to Privileged Group

Add user in a potential privileged group which can be used to elevate privileges on the system

• Effort: advanced

Address Space Layout Randomization (ASLR) Alteration

ASLR is a security feature used by the Operating System to mitigate memory exploit, attacker might want to disable it

• Effort: intermediate

Adexplorer Usage

Detects the usage of Adexplorer, a legitimate tool from the Sysinternals suite that could be abused by attackers as it can saves snapshots of the Active Directory Database.

• Effort: advanced

Advanced IP Scanner

Detects the use of Advanced IP Scanner. Seems to be a popular tool for ransomware groups.

• Effort: master

Audio Capture via PowerShell

Detects audio capture via PowerShell Cmdlet

• Effort: intermediate

BITSAdmin Download

Detects command to download file using BITSAdmin, a built-in tool in Windows. This technique is used by several threat actors to download scripts or payloads on infected system.

• Effort: advanced

BazarLoader Persistence Using Schtasks

Detects possible BazarLoader persistence using schtasks. BazarLoader will create a Scheduled Task using a specific command line to establish its persistence.

• Effort: intermediate

Bloodhound and Sharphound Tools Usage

Detects default process names and default command line parameters used by Bloodhound and Sharphound tools.

• Effort: intermediate

Blue Mockingbird Malware

Attempts to detect system changes made by Blue Mockingbird

• Effort: elementary

Burp Suite Tool Detected

Burp Suite is a cybersecurity tool. When used as a proxy service, its purpose is to intercept packets and modify them to send them to the server. Burp Collaborator is a network service that Burp Suite uses to help discover many kinds of vulnerabilities (vulnerabilities scanner)

• Effort: intermediate

CMSTP Execution

Detects various indicators of Microsoft Connection Manager Profile Installer execution

• Effort: intermediate

CVE-2021-34527 - PrintNightmare - Suspicious Actions From Spoolsv

Detects suspicious image loads and file creations from the spoolsv process which could be a sign of an attacker trying to exploit the PrintNightmare vulnerability, CVE-2021-34527. A remote code execution vulnerability exists when the Windows Print Spooler service improperly performs privileged file operations. An attacker who successfully exploited this vulnerability could run arbitrary code with SYSTEM privileges. This works as well as a Local Privilege escalation vulnerability. To fully work the rule requires to log for Loaded DLLs and File Creations, which can be done respectively using the Sysmon's event IDs 7 and 11.

• Effort: master

Capture a network trace with netsh.exe

Detects capture a network trace via netsh.exe trace functionality

• Effort: intermediate

Certificate Authority Modification

Installation of new certificate(s) in the Certificate Authority can be used to trick user when spoofing website or to add trusted destinations.

• Effort: master

Change Default File Association

When a file is opened, the default program used to open the file (also called the file association or handler) is checked. File association selections are stored in the Windows Registry and can be edited by users, administrators, or programs that have Registry access or by administrators using the built-in assoc utility. Applications can modify the file association for a given file extension to call an arbitrary program when a file with the given extension is opened.

• Effort: advanced

Clear EventLogs Through CommandLine

Detects a command that clears event logs which could indicate an attempt from an attacker to erase its previous traces.

• Effort: intermediate

Cmdkey Cached Credentials Recon

Detects usage of cmdkey to look for cached credentials.

• Effort: intermediate

Cobalt Strike Default Beacons Names

Detects the default names of Cobalt Strike beacons / payloads.

• Effort: elementary

Commonly Used Commands To Stop Services And Remove Backups

Detects specific commands used regularly by ransomwares to stop services or remove backups

• Effort: intermediate

Control Panel Items

Detects the malicious use of a control panel item

• Effort: advanced

Copying Sensitive Files With Credential Data

Detects copy of files with well-known filenames (sensitive files with credential data) using esentutl. This requires Windows Security event log with the Detailed File Share logging policy enabled.

• Effort: elementary

Cron Files Alteration

Cron Files and Cron Directory alteration used by attacker for persistency or privilege escalation.

• Effort: advanced

DNS Exfiltration and Tunneling Tools Execution

Well-known DNS exfiltration tools execution

• Effort: intermediate

Data Compressed With Rar

An adversary may compress data in order to make it portable and minimize the amount of data sent over the network, this could be done the popular rar command line program.

• Effort: master

Data Compressed With Rar With Password

An adversary may compress data in order to make it portable and minimize the amount of data sent over the network, this could be done the popular rar command line program. This is a more specific one for rar where the arguments allow to encrypt both file data and headers with a given password.

• Effort: intermediate

Debugging Software Deactivation

Deactivation of some debugging softwares using taskkill command. It was observed being used by Ransomware operators.

• Effort: elementary

Default Encoding To UTF-8 PowerShell

Detects PowerShell encoding to UTF-8, which is used by Sliver implants. The command line just sets the default encoding to UTF-8 in PowerShell.

• Effort: advanced

Disable Task Manager Through Registry Key

Detects commands used to disable the Windows Task Manager by modifying the proper registry key in order to impair security tools. This technique is used by the Agent Tesla RAT, among others.

• Effort: elementary

Disabled IE Security Features

Detects from the command lines or the registry, changes that indicate unwanted modifications to registry keys that disable important Internet Explorer security features. This has been used by attackers during Operation Ke3chang.

• Effort: advanced

Disabled Service

Service disabling can be abused by attacker to deny security mecanisms (eg: firewall, EDR, ect) and it is also often used by cryptominer to exploit as much RAM & CPU as possible on infected host.

• Effort: advanced

Domain Group And Permission Enumeration

Detects adversaries attempts to find domain-level groups and permission settings. Commands such as net group /domain of the Net utility can list domain-level groups The knowledge of domain-level permission groups can help adversaries determine which groups exist and which users belong to a particular group. Adversaries may use this information to determine which users have elevated permissions, such as domain administrators. Wizard Spider, FIN6, and other groups used net in their campaigns.

• Effort: advanced

Domain Trust Discovery Through LDAP

Detects attempts to gather information on domain trust relationships that may be used to identify lateral movement opportunities. "trustedDomain" which is detected here is a Microsoft Active Directory ObjectClass Type that represents a domain that is trusted by, or trusting, the local AD DOMAIN. Several tools are using LDAP queries in the end to get the information (DSQuery, sometimes ADFind as well, etc.)

• Effort: elementary

Dynamic Linker Hijacking From Environment Variable

LD_PRELOAD and LD_LIBRARY_PATH are environment variables used by the Operating System at the runtime to load shared objects (library.ies) when executing a new process, attacker can overwrite this variable to attempts a privileges escalation.

• Effort: advanced

ETW Tampering

Detects a command that clears or disables any ETW Trace log which could indicate a logging evasion

• Effort: intermediate

Elise Backdoor

Detects Elise backdoor activity as used by Lotus Blossom

• Effort: elementary

Empire Monkey Activity

Detects EmpireMonkey APT reported Activity

• Effort: elementary

Equation Group DLL_U Load

Detects a specific tool and export used by EquationGroup

• Effort: elementary

Erase Shell History

Malware and attacker try to reduce their fingerprints on compromised host by deleting shell history

• Effort: advanced

Exchange Mailbox Export

Detection of a standard Exchange Mailbox export, which stores all mails from a user in a pst file.

• Effort: intermediate

Exchange PowerShell Snap-Ins To Export Exchange Mailbox Data

Detects PowerShell SnapIn command line, often used with Get-Mailbox to export Exchange mailbox data.

• Effort: intermediate

Exchange Server Creating Unusual Files

Look for Microsoft Exchange Server’s Unified Messaging service creating non-standard content on disk, which could indicate web shells or other malicious content, suggesting exploitation of CVE-2021-26858 vulnerability

• Effort: intermediate

Exfiltration And Tunneling Tools Execution

Execution of well known tools for data exfiltration and tunneling

• Effort: advanced

Exfiltration Domain In Command Line

Detects commands containing a domain linked to http exfiltration.

• Effort: intermediate

Explorer Process Executing HTA File

Detects a suspicious execution of an HTA file by the explorer.exe process. This unusual activity was observed when running IcedID malspam.

• Effort: intermediate

Formbook File Creation DB1

Detects specific file creation (Users*\AppData\Local\Temp\DB1) to store data to exfiltrate (Formbook behavior). Logging for Sysmon event 11 is usually used for this detection.

• Effort: intermediate

Grabbing Sensitive Hives Via Reg Utility

Detects dump of SAM, System or Security hives using reg.exe utility. Adversaries may attempt to dump these Windows Registry to retrieve password hashes and access credentials.

• Effort: intermediate

HackTools Suspicious Process Names In Command Line

Detects the default process name of several HackTools and also check in command line. This rule is here for quickwins as it obviously has many blind spots.

• Effort: intermediate

Hiding Files With Attrib.exe

Detects usage of attrib.exe to hide files from users.

• Effort: advanced

High Privileges Network Share Removal

Detects high privileges shares being deleted with the net share command.

• Effort: intermediate

Hijack Legit RDP Session To Move Laterally

Identifies suspicious file creations in the startup folder of a remote system. An adversary could abuse this to move laterally by dropping a malicious script or executable that will be executed after a reboot or user logon.

• Effort: intermediate

ICacls Granting Access To All

Detects suspicious icacls command granting access to all, used by the ransomware Ryuk to delete every access-based restrictions on files and directories. ICacls is a built-in Windows command to interact with the Discretionary Access Control Lists (DACLs) which can grand adversaries higher permissions on specific files and folders.

• Effort: elementary

Inhibit System Recovery Deleting Backups

Detects adversaries attempts to delete backups or inhibit system recovery. This rule relies on differents known techniques using Windows events logs from Sysmon (ID 1), and PowerShell (ID 4103, 4104).

• Effort: intermediate

Interactive Terminal Spawned via Python

Identifies when a terminal (tty) is spawned via Python. Attackers may upgrade a simple reverse shell to a fully interactive tty after obtaining initial access to a host.

• Effort: advanced

KeePass Config XML In Command-Line

Detects a command-line interaction with the KeePass Config XML file. It could be used to retrieve informations or to be abused for persistence.

• Effort: intermediate

Kernel Module Alteration

Kernel module installation can be used to configure system settings to automatically execute a program during system boot or logon to maintain persistence or gain higher-level privileges on compromised systems.

• Effort: advanced

Koadic Execution

Detects command line parameters used by Koadic hack tool

• Effort: intermediate

Lazarus Loaders

Detects different loaders used by the Lazarus Group APT

• Effort: elementary

List Shadow Copies

Detects command line used to list shadow copies. An adversary may attempt to get information on shadow volumes to perform deletion or extract password hashes from the ntds.dit file. This rule requires command line logging or Windows PowerShell events (4104).

• Effort: master

MSBuild Abuse

Detection of MSBuild uses by attackers to infect an host. Focuses on XML compilation which is a Metasploit payload, and on connections made by this process which is unusual.

• Effort: intermediate

MalwareBytes Uninstallation

Detects command line being used by attackers to uninstall Malwarebytes.

• Effort: intermediate

MavInject Process Injection

Detects process injection using the signed Windows tool Mavinject32.exe (which is a LOLBAS)

• Effort: intermediate

Meterpreter or Cobalt Strike Getsystem Service Installation

Detects the use of getsystem Meterpreter/Cobalt Strike command by detecting some of the techniques being used (technique 1,2 and 5).

• Effort: elementary

Microsoft Office Creating Suspicious File

Detects Microsoft Office process (word, excel, powerpoint) creating a suspicious file which corresponds to a script or an executable. This behavior highly corresponds to an executed macro which loads an installation script or a malware payload. The rule requires to log for File Creations to work properly, which can be done through Sysmon Event ID 11.

• Effort: master

Msdt (Follina) File Browse Process Execution

Detects various Follina vulnerability exploitation techniques. This is based on the Compatability Troubleshooter which is abused to do code execution.

• Effort: elementary

Mshta JavaScript Execution

Identifies suspicious mshta.exe commands that execute JavaScript supplied as a command line argument.

• Effort: elementary

NTDS.dit File In Suspicious Directory

The file NTDS.dit is supposed to be located mainly in C:\Windows\NTDS. The rule checks whether the file is in a legitimate directory or not (through file creation events). This is usually really suspicious and could indicate an attacker trying copy the file to then look for users password hashes.

• Effort: advanced

NTDS.dit File Interaction Through Command Line

Detects interaction with the file NTDS.dit through command line. This is usually really suspicious and could indicate an attacker trying copy the file to then look for users password hashes.

• Effort: intermediate

Net.exe User Account Creation

Identifies creation of local users via the net.exe command

• Effort: master

NetSh Used To Disable Windows Firewall

Detects NetSh commands used to disable the Windows Firewall

• Effort: intermediate

Netsh Allow Command

Netsh command line to allow a program to pass through firewall.

• Effort: advanced

Netsh Allowed Python Program

Detects netsh command that performs modification on Firewall rules to allow the program python.exe. This activity is most likely related to the deployment of a Python server or an application that needs to communicate over a network. Threat actors could use it for data extraction, hosting a webshell or else.

• Effort: intermediate

Netsh Port Forwarding

Detects netsh commands that enable a port forwarding between to hosts. This can be used by attackers to tunnel RDP or SMB shares for example.

• Effort: elementary

Netsh Port Opening

Detects netsh commands that opens a specific port. Can be used by malware or attackers for lateralisation/exfiltration (e.g. SMB/RDP opening).

• Effort: master

Netsh RDP Port Forwarding

Detects netsh commands that configure a port forwarding of port 3389 used for RDP. This is commonly used by attackers during lateralization on windows environments.

• Effort: elementary

Netsh RDP Port Opening

Detects netsh commands that opens the port 3389 used for RDP, used in Sarwent Malware

• Effort: intermediate

Network Scanning and Discovery

Tools and command lines used for network discovery from current system

• Effort: advanced

Network Sniffing

List of common tools used for network packages sniffing

• Effort: advanced

Network Sniffing Windows

Network sniffing refers to using the network interface on a system to monitor or capture information sent over a wired or wireless connection. An adversary may place a network interface into promiscuous mode to passively access data in transit over the network, or use span ports to capture a larger amount of data.

• Effort: intermediate

New DLL Added To AppCertDlls Registry Key

Dynamic-link libraries (DLLs) that are specified in the AppCertDLLs value in the Registry key can be abused to obtain persistence and privilege escalation by causing a malicious DLL to be loaded and run in the context of separate processes on the computer. Logging for Registry events is needed in the Sysmon configuration (events 12 and 13).

• Effort: intermediate

New Service Creation

Detects creation of a new service from command line

• Effort: advanced

Ngrok Process Execution

Detects possible Ngrok execution, which can be used by attacker for RDP tunneling.

• Effort: intermediate

NlTest Usage

Detects attempts to gather information on domain trust relationships that may be used to identify lateral movement opportunities. These command lines were observed in numerous attacks, but also sometimes from legitimate administrators for debugging purposes. The rule does not cover very basics commands but rather the ones that are interesting for attackers to gather information on a domain.

• Effort: intermediate

Non-Legitimate Executable Using AcceptEula Parameter

Detects accepteula in command line with non-legitimate executable name. Some attackers are masquerading SysInternals tools with decoy names to prevent detection.

• Effort: intermediate

OneNote Embedded File

Detects creation or uses of OneNote embedded files with unusual extensions.

• Effort: intermediate

Opening Of a Password File

Command line detection of common office software opening some password related file. It could be a security breach if an unauthorized user access it.

• Effort: advanced

Outlook Registry Access

Detection of accesses to Microsoft Outlook registry hive, which might contain sensitive information.

• Effort: elementary

Package Manager Alteration

Package manager (eg: apt, yum) can be altered to install malicious software

• Effort: advanced

PasswordDump SecurityXploded Tool

Detects the execution of the PasswordDump SecurityXploded Tool

• Effort: elementary

Phorpiex DriveMgr Command

Detects specific command used by the Phorpiex botnet to execute a copy of the loader during its self-spreading stage. As described by Microsoft, this behavior is unique and easily identifiable due to the use of folders named with underscores "__" and the PE name "DriveMgr.exe".

• Effort: elementary

Phorpiex Process Masquerading

Detects specific process executable path used by the Phorpiex botnet to masquerade its system process network activity. It looks for a pattern of a system process executable name that is not legitimate and running from a folder that is created via a random algorithm 13-15 numbers long.

• Effort: elementary

PowerCat Function Loading

Detect a basic execution of PowerCat. PowerCat is a PowerShell function allowing to do basic connections, file transfer, shells, relays, generate payloads.

• Effort: intermediate

PowerShell AMSI Deactivation Bypass Using .NET Reflection

Detects Request to amsiInitFailed that can be used to disable AMSI (Antimalware Scan Interface) Scanning. More information about Antimalware Scan Interface https://docs.microsoft.com/en-us/windows/win32/amsi/antimalware-scan-interface-portal.

• Effort: elementary

PowerShell Downgrade Attack

Detects PowerShell downgrade attack by comparing the host versions with the actually used engine version 2.0

• Effort: elementary

PowerShell Download From URL

Detects a Powershell process that contains download commands in its command line string

• Effort: intermediate

PowerShell EncodedCommand

Detects popular file extensions in commands obfuscated in base64 run through the EncodedCommand option.

• Effort: advanced

PowerShell Execution Via Rundll32

Detects PowerShell Strings applied to rundll as seen in PowerShdll.dll Rule modified

• Effort: intermediate

PowerShell Malicious Nishang PowerShell Commandlets

Detects Commandlet names and arguments from the Nishang exploitation framework

• Effort: advanced

Powershell UploadString Function

Powershell's uploadXXX functions are a category of methods which can be used to exfiltrate data through native means on a Windows host.

• Effort: intermediate

Powershell Web Request

Detects the use of various web request methods executed remotely via Windows PowerShell

• Effort: advanced

Process Memory Dump Using Comsvcs

Detects the use of comsvcs in command line to dump a specific proces memory. This techinique is widlely used by attackers for privilege escalation and pivot.

• Effort: elementary

Process Trace Alteration

PTrace syscall provides a means by which one process ("tracer") may observe and control the execution of another process ("tracee") and examine and change the tracee's memory and registers. Attacker might want to abuse ptrace functionnality to analyse memory process. It requires to be admin or set ptrace_scope to 0 to allow all user to trace any process.

• Effort: advanced

PsExec Process

Detects PsExec execution, command line which contains pstools or installation of the PsExec service. PsExec is a SysInternals which can be used to execute a program on another computer. The tool is as much used by attackers as by administrators.

• Effort: advanced

Python Exfiltration Tools

Python has some built-in modules or library that could be installed and later be used as exflitration tool by an attacker

• Effort: advanced

Python HTTP Server

Detects command used to start a Simple HTTP server in Python. Threat actors could use it for data extraction, hosting a webshell or else.

• Effort: intermediate

Python Offensive Tools and Packages

Track installation and usage of offensive python packages and project that are used for lateral movement

• Effort: master

Qakbot Persistence Using Schtasks

Detects possible Qakbot persistence using schtasks.

• Effort: intermediate

RDP Session Discovery

Detects use of RDP session discovery via qwinsta or quser. Used by some threat actors to know if someone is working via RDP on a server.

• Effort: advanced

RTLO Character

Detects RTLO (Right-To-Left character) in file and process names.

• Effort: elementary

RYUK Ransomeware - martinstevens Username

Detects user name "martinstevens". Wizard Spider is used to add the user name "martinstevens" to the AD of its victims. It was observed in several campaigns; in 2019 and 2020.

• Effort: elementary

Raccine Uninstall

Detects commands that indicate a Raccine removal from an end system. Raccine is a free ransomware protection tool.

• Effort: elementary

Rclone Process

Detects Rclone executable or Rclone execution by using the process name, the execution through a command obfuscated or not.

• Effort: advanced

RedMimicry Winnti Playbook Registry Manipulation

Detects actions caused by the RedMimicry Winnti playbook. Logging for Registry events is needed in the Sysmon configuration (events 12 and 13).

• Effort: elementary

Rubeus Tool Command-line

Detects command line parameters used by Rubeus, a toolset to interact with Kerberos and abuse it.

• Effort: advanced

SEKOIA.IO Intelligence Feed

Detect threats based on indicators of compromise (IOCs) collected by SEKOIA's Threat and Detection Research team.

• Effort: elementary

SELinux Disabling

An attacker can disable SELinux to make workstation or server compromise easier as it disables several protections.

• Effort: intermediate

SOCKS Tunneling Tool

Detects the usage of a SOCKS tunneling tool, often used by threat actors. These tools often use the socks5 commandline argument, however socks4 can sometimes be used as well. Unfortunately, socks alone (without any number) triggered too many false positives.

• Effort: intermediate

SSH Authorized Key Alteration

The file authorized_keys is used by SSH server to identify SSH keys that are authorized to connect to the host, alteration of one of those files might indicate a user compromision

• Effort: advanced

Schtasks Persistence With High Privileges

Detection of scheduled task with high privileges used by attacker for persistence.

• Effort: elementary

Socat Relaying Socket

Socat is a linux tool used to relay local socket or internal network connection, this technics is often used by attacker to bypass security equipment such as firewall

• Effort: intermediate

Socat Reverse Shell Detection

Socat is a linux tool used to relay or open reverse shell that is often used by attacker to bypass security equipment

• Effort: intermediate

SolarWinds Suspicious File Creation

Detects SolarWinds process creating a file with a suspicious extension. The process solarwinds.businesslayerhost.exe created an unexpected file whose extension is ".exe", ".ps1", ".jpg", ".png" or ".dll".

• Effort: intermediate

Spyware Persistence Using Schtasks

Detects possible Agent Tesla or Formbook persistence using schtasks. The name of the scheduled task used by these malware is very specific (Updates/randomstring).

• Effort: intermediate

Suncrypt Parameters

Detects SunCrypt ransomware's parameters, most of which are unique.

• Effort: elementary

Suspicious ADSI-Cache Usage By Unknown Tool

Detects the usage of ADSI (LDAP) operations by tools. This may also detect tools like LDAPFragger. It needs file monitoring capabilities (Sysmon Event ID 11 with .sch file creation logging).

• Effort: advanced

Suspicious Cmd File Copy Command To Network Share

Copy suspicious files through Windows cmd prompt to network share

• Effort: intermediate

Suspicious Control Process

Detects suspicious execution of control.exe process when used to execute a DLL file.

• Effort: advanced

Suspicious DLL Loading By Ordinal

Detects suspicious DLL Loading by ordinal number in a non legitimate or rare folders. For example, Sofacy (APT28) used this technique to load their Trojan in a campaign of 2018.

• Effort: intermediate

Suspicious Double Extension

Detects suspicious use of an .exe extension after a non-executable file extension like .pdf.exe, a set of spaces or underlines to cloak the executable file in spearphishing campaigns

• Effort: elementary

Suspicious Finger Usage

Detects suspicious aged finger.exe tool execution often used in malware attacks nowadays. An attacker can use finger to silently retrieve a command, a script or a payload from a remote server. For example, the tool Darkfinger-C2 uses this technique to download files from the C2 channel.

• Effort: intermediate

Suspicious Mshta Execution

Detects suspicious mshta.exe execution patterns, either involving file polyglotism, remote file (http, ftp or ldap) or suspicious location. This technique is often used by threat actors.

• Effort: intermediate

Suspicious Netsh DLL Persistence

Detects persitence via netsh helper. Netsh interacts with other operating system components using dynamic-link library (DLL) files. Adversaries may establish persistence by executing malicious content triggered by Netsh Helper DLLs.

• Effort: elementary

Suspicious Network Args In Command Line

Detection on suspicious network arguments in processes command lines using HTTP schema with port 443.

• Effort: intermediate

Suspicious PowerShell Invocations - Specific

Detects suspicious PowerShell invocation command parameters

• Effort: intermediate

Suspicious PrinterPorts Creation (CVE-2020-1048)

Detects new commands that add new printer port which point to suspicious file

• Effort: advanced

Suspicious Rundll32.exe Execution

The process rundll32.exe executes a newly dropped DLL with update /i in the command line. This specific technic was observed at least being used by the IcedID loading mechanism dubbed Gziploader.

• Effort: intermediate

Suspicious Taskkill Command

Detects rare taskkill command being used. It could be related to Baby Shark malware.

• Effort: intermediate

Suspicious VBS Execution Parameter

Detects suspicious VBS file execution with a specific parameter by cscript. It was observed in the Operation CloudHopper.

• Effort: elementary

Suspicious Windows Defender Exclusion Command

Detects PowerShell commands aiming to exclude path, process, IP address, or extension from scheduled and real-time scanning. These commands can be used by attackers or malware to avoid being detected by Windows Defender. Depending on the environment and the installed software, this detection rule could raise false positives. We recommend customizing this rule by filtering legitimate processes that use Windows Defender exclusion command in your environment.

• Effort: master

Suspicious Windows Installer Execution

Detects suspicious execution of the Windows Installer service (msiexec.exe) which could be used to install a malicious MSI package hosted on a remote server.

• Effort: intermediate

Suspicious Windows Script Execution

Detects wscript.exe or cscript.exe executing a script in user directories (C:\ProgramData or C:\Users) with a .txt extension, which is very suspicious. It could strongly correspond to a malware dropper, as seen during SquirrelWaffle maldoc campaign.

• Effort: intermediate

Suspicious certutil command

Detects suspicious certutil command which can be used by threat actors to download and/or decode payload.

• Effort: intermediate

Suspicious desktop.ini Action

Detects unusual processes accessing desktop.ini, which can be leveraged to alter how Explorer displays a folder's content (i.e. renaming files) without changing them on disk.

• Effort: advanced

Sysprep On AppData Folder

Detects suspicious Sysprep process start with AppData folder as target (as used by Trojan Syndicasec in Thrip report by Symantec). Sysprep is a Windows tool used to change Windows images from a generalized state to a specialized state, and then back to a generalized state. It can be used to remove all system-specific information and reset the computer.

• Effort: intermediate

System Info Discovery

System info discovery, attempt to detects basic command use to fingerprint a host

• Effort: master

Telegram Bot API Request

Detects suspicious DNS queries to api.telegram.org used by Telegram Bots of any kind

• Effort: advanced

Usage Of Procdump With Common Arguments

Detects the usage of Procdump sysinternals tool with some common arguments and followed by common patterns.

• Effort: intermediate

WAF Block Rule

Detects when one of WAF rule blocked an HTTP request

• Effort: master

WCE wceaux.dll Creation

Detects wceaux.dll creation while Windows Credentials Editor (WCE) is executed.

• Effort: intermediate

WMI Install Of Binary

Detection of WMI used to install a binary on the host. It is often used by attackers as a signed binary to infect an host.

• Effort: elementary

WMI Persistence Script Event Consumer File Write

Detects file writes through WMI script event consumer.

• Effort: advanced

WMIC Uninstall Product

Detects products being uninstalled using WMIC command.

• Effort: intermediate

Webshell Creation

Detects possible webshell file creation. It requires File Creation monitoring, which can be done using Sysmon's Event ID 11. However the recommended SwiftOnSecurity configuration does not fully cover the needs for this rule, it needs to be updated with the proper file names extensions.

• Effort: master

WiFi Credentials Harvesting Using Netsh

Detects the harvesting of WiFi credentials using netsh.exe, used in particular by Agent Tesla (RAT) and Turla Mosquito (RAT)

• Effort: elementary

Windows Defender Disabled

The rule detects attempts to deactivate/disable Windows Defender through command line or registry. To fully use this rule Windows Registry logging is needed. This can be done for instance using Sysmon with Event IDs 12,13 and 14 (and adding the correct path in its configuration).

• Effort: intermediate

Windows Defender Disabled Base64 Encoded

Detects attempts to deactivate/disable Windows Defender through base64 encoded PowerShell command line.

• Effort: elementary

Windows Defender History Directory Deleted

Windows Defender history directory has been deleted. Could be an attempt by an attacker to remove its traces.

• Effort: elementary

Windows Defender Set-MpPreference Base64 Encoded

Detects changes of preferences for Windows Defender scan and updates. Configure Windows Defender using base64-encoded commands is suspicious and could be related to malicious activities.

• Effort: intermediate

Windows Defender Signatures Removed With MpCmdRun

Detects attempts to remove Windows Defender Signatures using MpCmdRun legitimate Windows Defender executable. No signatures mean Windows Defender will be less effective (or completely useless depending on the option used).

• Effort: elementary

Windows Firewall Changes

Detects changes on Windows Firewall configuration

• Effort: master

Wmic Process Call Creation

The WMI command-line (WMIC) utility provides a command-line interface for Windows Management Instrumentation (WMI). WMIC is compatible with existing shells and utility commands. Although WMI is supposed to be an administration tool, it is wildy abused by threat actors. One of the reasons is WMI is quite stealthy. This rule detects the wmic command line launching a process on a remote or local host.

• Effort: intermediate

Wmic Service Call

Detects either remote or local code execution using wmic tool.

• Effort: intermediate

XCopy Suspicious Usage

Detects the usage of xcopy with suspicious command line options (used by Judgment Panda APT in the past). The rule is based on command line only in case xcopy is renamed.

• Effort: advanced

XSL Script Processing And SquiblyTwo Attack

Detection of an attack where adversaries may bypass application control and obscure execution of code by embedding scripts inside XSL files. Another variation of this technique, dubbed "Squiblytwo", involves to invoke JScript or VBScript within an XSL file.

• Effort: intermediate

Event Categories

The following table lists the data source offered by this integration.

Data Source	Description
Host network interface	every packets are logged and information on the outcome, the source/destination are extracted
Network device logs	ACL logs are examined in detail
Network protocol analysis	packets are fully analyzed

In details, the following table denotes the type of events produced by this integration.

Name	Values
Kind	event
Category	host
Type	info

Event Samples

Find below few samples of events and how they are normalized by SEKOIA.IO.

test_arp_src_ip.jsontest_authpriv.jsontest_daemon.jsontest_if_down_admin_down.jsontest_if_down_cfg_change.jsontest_if_duplex.jsontest_if_rx_flow_control.jsontest_if_speed.jsontest_if_up.jsontest_port_channel_members_down.jsontest_port_channel_suspended.jsontest_user.jsontest_vshd_syslog_cmd_exec.jsontest_vshd_syslog_config.jsontest_vshd_syslog_config2.json

{
    "message": "2023 Jan 11 19:27:57 CET: %ARP-2-DUP_SRC_IP: arp [20856] Source address of packet received from 0050.5683.69cd on Vlan756(port-channel100) is duplicate of local, 10.30.38.5 (message repeated 1 time)",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 2,
        "code": "DUP_SRC_IP",
        "reason": "arp [20856] Source address of packet received from 0050.5683.69cd on Vlan756(port-channel100) is duplicate of local, 10.30.38.5 (message repeated 1 time)"
    },
    "@timestamp": "2023-01-11T18:27:57.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "source": {
        "ip": "10.30.38.5",
        "address": "10.30.38.5"
    },
    "host": {
        "mac": "00:50:56:83:69:CD"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "ARP"
            },
            "observer": {
                "interface": {
                    "name": "port-channel100"
                },
                "vlan": "Vlan756"
            }
        }
    },
    "related": {
        "ip": [
            "10.30.38.5"
        ]
    }
}

{
    "message": "2023 Jan 15 00:31:52 CET: %AUTHPRIV-3-SYSTEM_MSG: pam_aaa:Authentication failed from 1.2.3.4 - dcos_sshd[6531]",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 3,
        "code": "SYSTEM_MSG",
        "reason": "pam_aaa:Authentication failed from 1.2.3.4 - dcos_sshd[6531]",
        "module": "pam"
    },
    "@timestamp": "2023-01-14T23:31:52.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "source": {
        "ip": "1.2.3.4",
        "address": "1.2.3.4"
    },
    "process": {
        "pid": 6531,
        "name": "dcos_sshd"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "AUTHPRIV",
                "outcome": "failure"
            }
        }
    },
    "related": {
        "ip": [
            "1.2.3.4"
        ]
    }
}

{
    "message": "2023 Jan 15 00:31:52 CET: %DAEMON-3-SYSTEM_MSG: error: PAM: Authentication failure for illegal user USERID from 4.3.6.5 - dcos_sshd[6526]",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 3,
        "code": "SYSTEM_MSG",
        "reason": "error: PAM: Authentication failure for illegal user USERID from 4.3.6.5 - dcos_sshd[6526]",
        "module": "pam"
    },
    "@timestamp": "2023-01-14T23:31:52.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "source": {
        "ip": "4.3.6.5",
        "address": "4.3.6.5"
    },
    "user": {
        "name": "USERID"
    },
    "process": {
        "pid": 6526,
        "name": "dcos_sshd"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "DAEMON",
                "outcome": "failure"
            }
        }
    },
    "related": {
        "ip": [
            "4.3.6.5"
        ],
        "user": [
            "USERID"
        ]
    }
}

{
    "message": "2023 Jan 17 12:23:16 CET: %ETHPORT-5-IF_DOWN_ADMIN_DOWN: Interface Ethernet1/38 (description:SRV-01) is down (Administratively down)",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 5,
        "code": "IF_DOWN_ADMIN_DOWN",
        "reason": "Administratively down",
        "action": "down"
    },
    "@timestamp": "2023-01-17T11:23:16.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "ETHPORT"
            },
            "observer": {
                "interface": {
                    "name": "Ethernet1/38"
                }
            }
        }
    }
}

{
    "message": "2023 Jan 17 12:23:15 CET: %ETHPORT-5-IF_DOWN_CFG_CHANGE: Interface Ethernet1/38 (description:SRV-01) is down(Config change)",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 5,
        "code": "IF_DOWN_CFG_CHANGE",
        "reason": "Config change",
        "action": "down"
    },
    "@timestamp": "2023-01-17T11:23:15.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "ETHPORT"
            },
            "observer": {
                "interface": {
                    "name": "Ethernet1/38"
                }
            }
        }
    }
}

{
    "message": "2023 Jan 11 18:43:54 CET: %ETHPORT-5-IF_DUPLEX: Interface Ethernet1/38, operational duplex mode changed to Full",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 5,
        "code": "IF_DUPLEX",
        "reason": "operational duplex mode changed to Full"
    },
    "@timestamp": "2023-01-11T17:43:54.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "ETHPORT"
            },
            "observer": {
                "interface": {
                    "name": "Ethernet1/38"
                }
            }
        }
    }
}

{
    "message": "2023 Jan 11 18:43:54 CET: %ETHPORT-5-IF_RX_FLOW_CONTROL: Interface Ethernet1/38, operational Receive Flow Control state changed to off",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 5,
        "code": "IF_RX_FLOW_CONTROL",
        "reason": "operational Receive Flow Control state changed to off"
    },
    "@timestamp": "2023-01-11T17:43:54.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "ETHPORT"
            },
            "observer": {
                "interface": {
                    "name": "Ethernet1/38"
                }
            }
        }
    }
}

{
    "message": "2023 Jan 11 18:43:54 CET: %ETHPORT-5-SPEED: Interface Ethernet1/38, operational speed changed to 1 Gbps",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 5,
        "code": "SPEED",
        "reason": "operational speed changed to 1 Gbps"
    },
    "@timestamp": "2023-01-11T17:43:54.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "ETHPORT"
            },
            "observer": {
                "interface": {
                    "name": "Ethernet1/38"
                }
            }
        }
    }
}

{
    "message": "2023 Jan 17 12:23:02 CET: %ETHPORT-5-IF_UP: Interface Ethernet1/38 (description:SRV-01) is up in mode access",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 5,
        "code": "IF_UP",
        "reason": "Interface Ethernet1/38 (description:SRV-01) is up in mode access",
        "action": "up"
    },
    "@timestamp": "2023-01-17T11:23:02.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "ETHPORT"
            },
            "observer": {
                "interface": {
                    "name": "Ethernet1/38"
                }
            }
        }
    }
}

{
    "message": "2023 Jan 11 16:46:31 CET: %ETHPORT-5-IF_DOWN_PORT_CHANNEL_MEMBERS_DOWN: Interface port-channel110 is down (No operational members)",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 5,
        "code": "IF_DOWN_PORT_CHANNEL_MEMBERS_DOWN",
        "reason": "No operational members",
        "action": "down"
    },
    "@timestamp": "2023-01-11T15:46:31.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "ETHPORT"
            },
            "observer": {
                "interface": {
                    "name": "port-channel110"
                }
            }
        }
    }
}

{
    "message": "2023 Jan 11 16:46:45 CET: %ETH_PORT_CHANNEL-5-PORT_SUSPENDED: Ethernet1/38: Ethernet1/38 is suspended",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 5,
        "code": "PORT_SUSPENDED",
        "reason": "Ethernet1/38 is suspended"
    },
    "@timestamp": "2023-01-11T15:46:45.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "ETH_PORT_CHANNEL"
            },
            "observer": {
                "interface": {
                    "name": "Ethernet1/38"
                }
            }
        }
    }
}

{
    "message": "2023 Jan 13 02:11:53 CET: %USER-3-SYSTEM_MSG: Failed to open file: No such file or directory - securityd",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 3,
        "code": "SYSTEM_MSG",
        "reason": "No such file or directory"
    },
    "@timestamp": "2023-01-13T01:11:53.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "file": {
        "name": "securityd"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "USER",
                "outcome": "failure"
            }
        }
    }
}

{
    "message": "2023 Jan 11 19:06:23 CET: %VSHD-5-VSHD_SYSLOG_CMD_EXEC: User:jdoe executed the command:securityd",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 5,
        "code": "VSHD_SYSLOG_CMD_EXEC",
        "reason": "User:jdoe executed the command:securityd"
    },
    "@timestamp": "2023-01-11T18:06:23.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "user": {
        "name": "jdoe"
    },
    "process": {
        "command_line": "securityd",
        "args": [
            "securityd"
        ],
        "executable": "securityd",
        "name": "securityd"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "VSHD"
            }
        }
    },
    "related": {
        "user": [
            "jdoe"
        ]
    }
}

{
    "message": "2023 Jan 11 19:00:56 CET: %VSHD-5-VSHD_SYSLOG_CONFIG_I: Configured from vty by jdoe on 1.2.3.4@pts/0",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 5,
        "code": "VSHD_SYSLOG_CONFIG_I",
        "reason": "Configured from vty by jdoe on 1.2.3.4@pts/0"
    },
    "@timestamp": "2023-01-11T18:00:56.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "destination": {
        "ip": "1.2.3.4",
        "address": "1.2.3.4"
    },
    "user": {
        "name": "jdoe"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "VSHD"
            },
            "observer": {
                "terminal": "pts/0"
            }
        }
    },
    "related": {
        "ip": [
            "1.2.3.4"
        ],
        "user": [
            "jdoe"
        ]
    }
}

{
    "message": "2023 Jan 11 19:00:56 CET: %VSHD-5-VSHD_SYSLOG_CONFIG_I: Configured from vty by jdoe on console",
    "event": {
        "kind": "event",
        "category": [
            "host"
        ],
        "type": [
            "info"
        ],
        "severity": 5,
        "code": "VSHD_SYSLOG_CONFIG_I",
        "reason": "Configured from vty by jdoe on console"
    },
    "@timestamp": "2023-01-11T18:00:56.000000Z",
    "observer": {
        "vendor": "Cisco",
        "product": "NX-OS"
    },
    "user": {
        "name": "jdoe"
    },
    "cisco": {
        "nxos": {
            "event": {
                "facility": "VSHD"
            },
            "observer": {
                "terminal": "console"
            }
        }
    },
    "related": {
        "user": [
            "jdoe"
        ]
    }
}

Extracted Fields

The following table lists the fields that are extracted, normalized under the ECS format, analyzed and indexed by the parser. It should be noted that infered fields are not listed.

Name	Type	Description
@timestamp	date	Date/time when the event originated.
cisco.nxos.event.facility	keyword	The facility of the event
cisco.nxos.observer.interface.name	keyword	The name of the interface
cisco.nxos.observer.terminal	keyword	The identifier of the terminal used for the action
cisco.nxos.observer.vlan	keyword	The virtual lan of the observed packet
destination.domain	keyword	The domain name of the destination.
destination.ip	ip	IP address of the destination.
event.action	keyword	The action captured by the event.
event.category	keyword	Event category. The second categorization field in the hierarchy.
event.code	keyword	Identification code for this event.
event.kind	keyword	The kind of the event. The highest categorization field in the hierarchy.
event.module	keyword	Name of the module this data is coming from.
event.reason	keyword	Reason why this event happened, according to the source
event.severity	long	Numeric severity of the event.
event.type	keyword	Event type. The third categorization field in the hierarchy.
file.name	keyword	Name of the file including the extension, without the directory.
file.path	keyword	Full path to the file, including the file name.
host.mac	keyword	Host MAC addresses.
observer.product	keyword	The product name of the observer.
observer.vendor	keyword	Vendor name of the observer.
process.args	keyword	Array of process arguments.
process.command_line	wildcard	Full command line that started the process.
process.executable	keyword	Absolute path to the process executable.
process.name	keyword	Process name.
process.pid	long	Process id.
source.ip	ip	IP address of the source.
user.name	keyword	Short name or login of the user.

Configure

Prerequisites

An internal log concentrator is required to collect and forward events to SEKOIA.IO.

Enable Syslog forwarding

Log on your Cisco appliance and follow this guide to enable syslog forwarding.

Create the intake

Go to the intake page and create a new intake from the format Cisco NX-OS.

Transport to SEKOIA.IO

Please consult the Syslog Forwarding documentation to forward these logs to SEKOIA.IO.

Further Readings

• Cisco Nexus 9000 Series Documentation