YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_APT_Sandworm_SSHD_Config_Modification_May20_1

Detects ssh config entry inserted by Sandworm on compromised machines

APT / threat actorSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X

Author: Florian Roth (Nextron Systems)
Date: 2020-05-28
Modified: 2023-12-05
Score / Quality: 75 / 85

What this rule detects

Detects ssh config entry inserted by Sandworm on compromised machines

It defines 2 patterns (2 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

apt-sandworm-sshd-config-modification-may20-1.yarDetection Rule License 1.1

rule SIGNATURE_BASE_APT_Sandworm_SSHD_Config_Modification_May20_1 : FILE
{
	meta:
		description = "Detects ssh config entry inserted by Sandworm on compromised machines"
		author = "Florian Roth (Nextron Systems)"
		id = "dd60eeb7-3d4b-5a6a-8054-50c617ee8c73"
		date = "2020-05-28"
		modified = "2023-12-05"
		reference = "https://media.defense.gov/2020/May/28/2002306626/-1/-1/0/CSA%20Sandworm%20Actors%20Exploiting%20Vulnerability%20in%20Exim%20Transfer%20Agent%2020200528.pdf"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_sandworm_exim_expl.yar#L33-L49"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "dc074464e50502459038ac127b50b8c68ed52817a61c2f97f0add33447c8f730"
		hash = "538d713cb47a6b5ec6a3416404e0fc1ebcbc219a127315529f519f936420c80e"
		logic_hash = "5775588b3a9d44e9eb2c8ef0f50351d7e3b06f1005f669775fae7187900d5999"
		score = 75
		quality = 85
		tags = "FILE"

	strings:
		$x1 = "AllowUsers mysql_db" ascii
		$a1 = "ListenAddress" ascii fullword

	condition:
		filesize < 10KB and all of them
}

Strings (2 patterns)

Identifier	Type	Value	Modifiers
$x1	text	"AllowUsers mysql_db"	ascii
$a1	text	"ListenAddress"	ascii fullword

Condition

filesize < 10KB and all of them

In plain words (Heuristic)

The file must be smaller than 10KB (a cheap guard that skips large files).
All patterns in the rule must match.

Test this rule in your browser

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References

https://media.defense.gov/2020/May/28/2002306626/-1/-1/0/CSA%20Sandworm%20Actors%20Exploiting%20Vulnerability%20in%20Exim%20Transfer%20Agent%2020200528.pdf

Sample hashes

Hashes of samples the author lists in the rule's meta (look them up in your threat-intelligence platform).

dc074464e50502459038ac127b50b8c68ed52817a61c2f97f0add33447c8f730
538d713cb47a6b5ec6a3416404e0fc1ebcbc219a127315529f519f936420c80e

Licence & attribution

Author: Florian Roth (Nextron Systems)

Source repository: Signature Base (Florian Roth / Nextron) @ 94a1c48d7a

Licence: Detection Rule License 1.1 (repository licence)

Original rule

Mirrored via YARA Forge 20260927, which prefixes rule names with the source and adds normalised meta fields.

Rule id: dd60eeb7-3d4b-5a6a-8054-50c617ee8c73

Tags:FILE

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