Skip to content
yararules.org
Menu

YARA · SEKOIA.IO Community

SEKOIA_Ransomware_Win_Avoslocker

Detect AvosLocker ransomware (2021-07)

MalwareAvos LockerSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X
Author
Sekoia.io
Date
2021-08-03
Modified
2024-12-19
Score / Quality
75 / 80

What this rule detects

Detect AvosLocker ransomware (2021-07)

Associated malware family: Avos Locker.

Targets: Windows PE.

It defines 4 patterns (4 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
ransomware-win-avoslocker.yarDetection Rule License 1.1
rule SEKOIA_Ransomware_Win_Avoslocker : FILE
{
	meta:
		description = "Detect AvosLocker ransomware (2021-07)"
		author = "Sekoia.io"
		id = "fc5c2483-48cb-4282-b6cb-ac728b948607"
		date = "2021-08-03"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/ransomware_win_avoslocker.yar#L1-L24"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		hash = "f810deb1ba171cea5b595c6d3f816127fb182833f7a08a98de93226d4f6a336f"
		hash = "c0a42741eef72991d9d0ee8b6c0531fc19151457a8b59bdcf7b6373d1fe56e02"
		hash = "84d94c032543e8797a514323b0b8fd8bd69b4183f17351628b13d1464093af2d"
		logic_hash = "d7f14f78ac569011ecf964109c72d75de4942361033a544350a2f73c7af64a0c"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$s1 = "cryptopp850\\rijndael_simd.cpp" ascii
		$s2 = "cryptopp850\\sha_simd.cpp" ascii
		$s3 = "cryptopp850\\gf2n_simd.cpp" ascii
		$s4 = "cryptopp850\\sse_simd.cpp" ascii

	condition:
		all of them and uint16( 0 ) == 0x5A4D and filesize > 900KB and filesize < 950KB
}

Strings (4 patterns)

IdentifierTypeValueModifiers
$s1text"cryptopp850\\rijndael_simd.cpp"ascii
$s2text"cryptopp850\\sha_simd.cpp"ascii
$s3text"cryptopp850\\gf2n_simd.cpp"ascii
$s4text"cryptopp850\\sse_simd.cpp"ascii

Condition

all of them and uint16( 0 ) == 0x5A4D and filesize > 900KB and filesize < 950KB

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must be smaller than 950KB (a cheap guard that skips large files).
  • The file must be larger than 900KB.
  • All patterns in the rule must match.

Test this rule in your browser

Drop a file to scan it with this rule using YARA-X compiled to WebAssembly. Nothing is uploaded.

Drop a file here or click to chooseScanned locally with YARA-X. Files up to 200 MB.

Open in editor

References

Sample hashes

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

  • f810deb1ba171cea5b595c6d3f816127fb182833f7a08a98de93226d4f6a336f
  • c0a42741eef72991d9d0ee8b6c0531fc19151457a8b59bdcf7b6373d1fe56e02
  • 84d94c032543e8797a514323b0b8fd8bd69b4183f17351628b13d1464093af2d

Licence & attribution

Author: Sekoia.io

Source repository: SEKOIA.IO Community @ a438a5901a

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: fc5c2483-48cb-4282-b6cb-ac728b948607

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE

Related rules

More Avos Locker rules