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ISC DHCP

Overview

ISC DHCP offers a complete open source solution for implementing DHCP servers.

The following Sekoia.io built-in rules match the intake ISC DHCP. This documentation is updated automatically and is based solely on the fields used by the intake which are checked against our rules. This means that some rules will be listed but might not be relevant with the intake.

SEKOIA.IO x ISC DHCP on ATT&CK Navigator

Cryptomining

Detection of domain names potentially related to cryptomining activities.

  • Effort: master
Dynamic DNS Contacted

Detect communication with dynamic dns domain. This kind of domain is often used by attackers. This rule can trigger false positive in non-controlled environment because dynamic dns is not always malicious.

  • Effort: master
Exfiltration Domain

Detects traffic toward a domain flagged as a possible exfiltration vector.

  • Effort: master
Remote Access Tool Domain

Detects traffic toward a domain flagged as a Remote Administration Tool (RAT).

  • Effort: master
SEKOIA.IO Intelligence Feed

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

  • Effort: elementary
Sekoia.io EICAR Detection

Detects observables in Sekoia.io CTI tagged as EICAR, which are fake samples meant to test detection.

  • Effort: master
TOR Usage Generic Rule

Detects TOR usage globally, whether the IP is a destination or source. TOR is short for The Onion Router, and it gets its name from how it works. TOR intercepts the network traffic from one or more apps on user’s computer, usually the user web browser, and shuffles it through a number of randomly-chosen computers before passing it on to its destination. This disguises user location, and makes it harder for servers to pick him/her out on repeat visits, or to tie together separate visits to different sites, this making tracking and surveillance more difficult. Before a network packet starts its journey, user’s computer chooses a random list of relays and repeatedly encrypts the data in multiple layers, like an onion. Each relay knows only enough to strip off the outermost layer of encryption, before passing what’s left on to the next relay in the list.

  • Effort: master

Event Categories

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

Data Source Description
Network device configuration logs include IP configuration of network devices in your networks

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

Name Values
Kind ``
Category network
Type connection

Event Samples

Find below few samples of events and how they are normalized by Sekoia.io.

{
    "message": "DHCPACK on 10.100.102.108 to 6c:88:14:1d:97:1c (PDB746) via 10.100.100.4",
    "event": {
        "category": [
            "network"
        ],
        "outcome": "success",
        "type": [
            "connection"
        ]
    },
    "destination": {
        "address": "10.100.100.4",
        "ip": "10.100.100.4"
    },
    "dhcpd": {
        "query": "ack"
    },
    "related": {
        "hosts": [
            "PDB746"
        ],
        "ip": [
            "10.100.100.4",
            "10.100.102.108"
        ]
    },
    "source": {
        "address": "PDB746",
        "domain": "PDB746",
        "ip": "10.100.102.108",
        "mac": "6c:88:14:1d:97:1c"
    }
}

{
    "message": "DHCPDISCOVER from ac:cc:8e:b0:2b:8c via 192.168.102.7: network 192.168.102.0/23: no free leases",
    "event": {
        "category": [
            "network"
        ],
        "outcome": "success",
        "type": [
            "connection"
        ]
    },
    "destination": {
        "address": "192.168.102.7",
        "ip": "192.168.102.7"
    },
    "dhcpd": {
        "query": "discover"
    },
    "related": {
        "ip": [
            "192.168.102.7"
        ]
    },
    "source": {
        "mac": "ac:cc:8e:b0:2b:8c"
    }
}

{
    "message": "DHCPRELEASE of 10.17.81.182 from 00:08:5d:71:92:15 (6867i00085D719105) via enp4s0f0 (found)",
    "event": {
        "category": [
            "network"
        ],
        "outcome": "success",
        "type": [
            "connection"
        ]
    },
    "dhcpd": {
        "query": "release"
    },
    "related": {
        "hosts": [
            "6867i00085D719105"
        ],
        "ip": [
            "10.17.81.182"
        ]
    },
    "source": {
        "address": "6867i00085D719105",
        "domain": "6867i00085D719105",
        "ip": "10.17.81.182",
        "mac": "00:08:5d:71:92:15"
    }
}

{
    "message": "DHCPREQUEST for 10.100.102.108 from 6c:88:14:1d:96:0c (PDB746) via 10.100.100.4",
    "event": {
        "category": [
            "network"
        ],
        "outcome": "success",
        "type": [
            "connection"
        ]
    },
    "destination": {
        "address": "10.100.100.4",
        "ip": "10.100.100.4"
    },
    "dhcpd": {
        "query": "request"
    },
    "related": {
        "hosts": [
            "PDB746"
        ],
        "ip": [
            "10.100.100.4",
            "10.100.102.108"
        ]
    },
    "source": {
        "address": "PDB746",
        "domain": "PDB746",
        "ip": "10.100.102.108",
        "mac": "6c:88:14:1d:96:0c"
    }
}

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
destination.ip ip IP address of the destination.
dhcpd.query keyword name of the DHCP query
event.category keyword Event category. The second categorization field in the hierarchy.
event.outcome keyword The outcome of the event. The lowest level categorization field in the hierarchy.
event.type keyword Event type. The third categorization field in the hierarchy.
source.domain keyword The domain name of the source.
source.ip ip IP address of the source.
source.mac keyword MAC address of the source.

Configure

As of now, the main solution to collect ISC DHCP logs leverages the Rsyslog recipe. Please share your experiences with other recipes by editing this documentation.

Rsyslog

Please refer to the documentation of ISC DHPD to forward events to your rsyslog server. The reader can consult the Rsyslog Transport documentation to forward these logs to Sekoia.io.