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YARA · Avast / Gen Digital IOC

AVASTTI_Cobaltstrike_Beacon_Xored_X64

No description has been set in the source file - AvastTI

Hack toolCobalt StrikeAvast / Gen Digital IOCDetection Rule License 1.1Compiles with YARA-X
Author
Gen Threat Labs
Date
2021-07-08
Modified
2026-03-11
Score / Quality
75 / 90

What this rule detects

No description has been set in the source file - AvastTI

Associated malware family: Cobalt Strike.

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
cobaltstrike-beacon-xored-x64.yarDetection Rule License 1.1
rule AVASTTI_Cobaltstrike_Beacon_Xored_X64
{
	meta:
		description = "No description has been set in the source file - AvastTI"
		author = "Gen Threat Labs"
		id = "15be610a-7552-5473-8da2-639220313783"
		date = "2021-07-08"
		modified = "2026-03-11"
		reference = "https://github.com/gendigitalinc/ioc"
		source_url = "https://github.com/avast/ioc/blob/a450ddabed95984422909c75ac52b6841f685983/CobaltStrike/yara_rules/cs_rules.yar#L728-L746"
		license_url = "N/A"
		logic_hash = "11e6c8be28325d42f24fb5bb43c0b5fd35990a46857bae7c9940262a33c02a8c"
		score = 75
		quality = 90
		tags = ""

	strings:
		$h01 = { FC 4883E4F0 EB33 5D 8B4500 4883C504 8B4D00 31C1 4883C504 55 8B5500 31C2 895500 31D0 4883C504 83E904 31D2 39D1 7402 EBE7 58 FC 4883E4F0 FFD0 E8C8FFFFFF }
		$h11 = { FC 4883E4F0 FFD0 E8C8FFFFFF }

	condition:
		$h01 and ( uint32be( @h11 + 12 ) ^ uint32be( @h11 + 20 ) == 0x4D5A4152 or uint32be( @h11 + 12 ) ^ uint32be( @h11 + 20 ) == 0x904D5A41 or uint32be( @h11 + 12 ) ^ uint32be( @h11 + 20 ) == 0x90904D5A or uint32be( @h11 + 12 ) ^ uint32be( @h11 + 20 ) == 0x9090904D or uint32be( @h11 + 12 ) ^ uint32be( @h11 + 20 ) == 0x90909090 )
}

Strings (2 patterns)

IdentifierTypeValueModifiers
$h01hex{ FC 4883E4F0 EB33 5D 8B4500 4883C504 8B4D00 31C1 4883C504 55 8B5500 31C2 895500 31D0 4883C504 83E904 31D2 39D1 7402 EBE7 58 FC 4883E4F0 FFD0 E8C8FFFFFF }
$h11hex{ FC 4883E4F0 FFD0 E8C8FFFFFF }

Condition

$h01 and ( uint32be( @h11 + 12 ) ^ uint32be( @h11 + 20 ) == 0x4D5A4152 or uint32be( @h11 + 12 ) ^ uint32be( @h11 + 20 ) == 0x904D5A41 or uint32be( @h11 + 12 ) ^ uint32be( @h11 + 20 ) == 0x90904D5A or uint32be( @h11 + 12 ) ^ uint32be( @h11 + 20 ) == 0x9090904D or uint32be( @h11 + 12 ) ^ uint32be( @h11 + 20 ) == 0x90909090 )

In plain words (Heuristic)

  • Pattern $h01 must be present.

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References

Licence & attribution

Author: Gen Threat Labs

Source repository: Avast / Gen Digital IOC @ a450ddabed

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: 15be610a-7552-5473-8da2-639220313783

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