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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_SUSP_Esxiargs_Endpoint_Conf_Aug23

Detects indicators found in endpoint.conf files as modified by actors in the ESXiArgs campaign

Suspicious / huntingSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Florian Roth
Date
2023-08-04
Modified
2023-12-05
Score / Quality
75 / 85

What this rule detects

Detects indicators found in endpoint.conf files as modified by actors in the ESXiArgs campaign

It defines 5 patterns (5 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
susp-esxiargs-endpoint-conf-aug23.yarDetection Rule License 1.1
rule SIGNATURE_BASE_SUSP_Esxiargs_Endpoint_Conf_Aug23 : FILE
{
	meta:
		description = "Detects indicators found in endpoint.conf files as modified by actors in the ESXiArgs campaign"
		author = "Florian Roth"
		id = "3e0b5dbf-7c5b-5599-823a-ce35fbdbe64b"
		date = "2023-08-04"
		modified = "2023-12-05"
		reference = "https://www.bleepingcomputer.com/forums/t/782193/esxi-ransomware-help-and-support-topic-esxiargs-args-extension/page-47"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/mal_ransom_esxi_attacks_feb23.yar#L103-L120"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		logic_hash = "794d460eec0e2f0b48e6ced94b125a1e48acde6be6281866e0b4a2ae6c2d3b51"
		score = 75
		quality = 85
		tags = "FILE"

	strings:
		$a1 = "/client/clients.xml" ascii
		$a2 = "/var/run/vmware/proxy-sdk-tunnel" ascii fullword
		$a3 = "redirect" ascii fullword
		$a4 = "allow" ascii fullword
		$s1 = " local 8008 allow allow"

	condition:
		filesize < 2KB and all of them
}

Strings (5 patterns)

IdentifierTypeValueModifiers
$a1text"/client/clients.xml"ascii
$a2text"/var/run/vmware/proxy-sdk-tunnel"ascii fullword
$a3text"redirect"ascii fullword
$a4text"allow"ascii fullword
$s1text" local 8008 allow allow"

Condition

filesize < 2KB and all of them

In plain words (Heuristic)

  • The file must be smaller than 2KB (a cheap guard that skips large files).
  • All patterns in the rule must match.

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References

Licence & attribution

Author: Florian Roth

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: 3e0b5dbf-7c5b-5599-823a-ce35fbdbe64b

Tags:FILE

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