Unbound

Overview

Unbound is a validating, recursive, and caching DNS resolver product from NLnet Labs. It is distributed free of charge in open-source form under the BSD license.

The following Sekoia.io built-in rules match the intake Unbound. 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 Unbound 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

Sliver DNS Beaconing

Detects suspicious DNS queries known from Sliver beaconing

Effort: intermediate

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
`DNS records`	unbound DNS queries

Event Samples

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

domain.jsonerror.jsonerror2.jsongenerate_keytag.jsoninfo_recursion.jsonip.jsonip_code.jsonserver_stats.jsonweird-hostname.json

{
    "message": "2019-10-08T11:29:05+02:00 hostfoo unbound[17265]: [17265:13] info: 127.0.0.1 reachms.corp.com. A IN",
    "dns": {
        "question": {
            "class": "IN",
            "name": "reachms.corp.com",
            "registered_domain": "corp.com",
            "subdomain": "reachms",
            "top_level_domain": "com",
            "type": "A"
        },
        "size_in_char": 16,
        "type": "query"
    },
    "host": {
        "name": "hostfoo"
    },
    "related": {
        "hosts": [
            "reachms.corp.com"
        ],
        "ip": [
            "127.0.0.1"
        ]
    },
    "source": {
        "address": "127.0.0.1",
        "ip": "127.0.0.1"
    }
}

{
    "message": "[3483:15] error: internal error: looping module stopped",
    "error": {
        "message": "looping module stopped",
        "type": "internal error"
    }
}

{
    "message": "[1678:6] error: failed to find an open port, drop msg",
    "error": {
        "message": "failed to find an open port, drop msg"
    }
}

{
    "message": "2019-10-08T11:29:05+02:00 hostfoo unbound[17265]: [265456:0] info: generate keytag query _ta-4f66. NULL IN",
    "host": {
        "name": "hostfoo"
    }
}

{
    "message": "2019-10-08T11:29:05+02:00 hostfoo unbound[17265]: [27060:0] info: average recursion processing time 0.007562 sec",
    "host": {
        "name": "hostfoo"
    }
}

{
    "message": "2019-10-08T11:29:04+02:00 hostfoo unbound[17265]: [17265:18] info: 192.168.1.1 1.1.1.1.in-addr.arpa. PTR IN",
    "dns": {
        "question": {
            "class": "IN",
            "name": "1.1.1.1.in-addr.arpa",
            "registered_domain": "1.in-addr.arpa",
            "subdomain": "1.1.1",
            "top_level_domain": "in-addr.arpa",
            "type": "PTR"
        },
        "size_in_char": 20,
        "type": "query"
    },
    "host": {
        "name": "hostfoo"
    },
    "related": {
        "hosts": [
            "1.1.1.1.in-addr.arpa"
        ],
        "ip": [
            "192.168.1.1"
        ]
    },
    "source": {
        "address": "192.168.1.1",
        "ip": "192.168.1.1"
    }
}

{
    "message": "2019-10-09T18:29:22+02:00 hostfoo unbound[3888]: [3888:1f] info: 192.168.1.1 1.1.168.192.in-addr.arpa. PTR IN",
    "dns": {
        "question": {
            "class": "IN",
            "name": "1.1.168.192.in-addr.arpa",
            "registered_domain": "192.in-addr.arpa",
            "subdomain": "1.1.168",
            "top_level_domain": "in-addr.arpa",
            "type": "PTR"
        },
        "size_in_char": 24,
        "type": "query"
    },
    "host": {
        "name": "hostfoo"
    },
    "related": {
        "hosts": [
            "1.1.168.192.in-addr.arpa"
        ],
        "ip": [
            "192.168.1.1"
        ]
    },
    "source": {
        "address": "192.168.1.1",
        "ip": "192.168.1.1"
    }
}

{
    "message": "2019-10-08T11:29:05+02:00 hostfoo unbound[17265]: [6634:16] info: server stats for thread 0: 11982 queries, 9074 answers from cache, 2908 recursions, 1029 prefetch, 0 rejected by ip ratelimiting",
    "host": {
        "name": "hostfoo"
    }
}

{
    "message": "[16667:e] info: 192.168.1.1 _ldap._tcp.SXB._sites.dc._msdcs.key.corp.net. SRV IN",
    "dns": {
        "question": {
            "class": "IN",
            "name": "_ldap._tcp.SXB._sites.dc._msdcs.key.corp.net",
            "registered_domain": "corp.net",
            "subdomain": "_ldap._tcp.SXB._sites.dc._msdcs.key",
            "top_level_domain": "net",
            "type": "SRV"
        },
        "size_in_char": 44,
        "type": "query"
    },
    "related": {
        "hosts": [
            "_ldap._tcp.SXB._sites.dc._msdcs.key.corp.net"
        ],
        "ip": [
            "192.168.1.1"
        ]
    },
    "source": {
        "address": "192.168.1.1",
        "ip": "192.168.1.1"
    }
}

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
`dns.question.class`	`keyword`	The class of records being queried.
`dns.question.name`	`keyword`	The name being queried.
`dns.question.type`	`keyword`	The type of record being queried.
`dns.size_in_char`	`number`
`dns.type`	`keyword`	The type of DNS event captured, query or answer.
`error.message`	`match_only_text`	Error message.
`error.type`	`keyword`	The type of the error, for example the class name of the exception.
`host.name`	`keyword`	Name of the host.
`source.domain`	`keyword`	The domain name of the source.
`source.ip`	`ip`	IP address of the source.
`source.port`	`long`	Port of the source.
`user.id`	`keyword`	Unique identifier of the user.
`user.name`	`keyword`	Short name or login of the user.

Configure

This setup guide will show you how to forward logs produced by your Unbound server to Sekoia.io by means of an rsyslog transport channel.

Configure the Rsyslog server

Please consult the Rsyslog Transport documentation to forward these logs to Sekoia.io.