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SEKOIA_Win_Malware_Janelarat_Strings

Detect the JanelaRAT malware

MalwareJanelaratSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X (with warnings)
Author
Sekoia.io
Date
2023-08-11
Modified
2024-12-19
Score / Quality
75 / 78

What this rule detects

Detect the JanelaRAT malware

Associated malware family: Janelarat.

Targets: Windows PE.

It defines 2 patterns (1 text, 1 hex, 0 regex).

YARA-X says: warning[text_as_hex]: hex pattern could be written as text literal

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
win-malware-janelarat-strings.yarDetection Rule License 1.1
rule SEKOIA_Win_Malware_Janelarat_Strings : FILE
{
	meta:
		description = "Detect the JanelaRAT malware"
		author = "Sekoia.io"
		id = "891f182e-8a7a-4d0c-a481-62c198bb901b"
		date = "2023-08-11"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/win_malware_janelarat_strings.yar#L1-L20"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		hash = "00df0a1f037e24ff1528d524fb7398735e2c3e0a9995a9f95a5293b04748f06e"
		logic_hash = "cf2ca92cf790211f69ea9645f1c1b865d5503d14a1dcce535b4a69c735ea3dad"
		score = 75
		quality = 78
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$s2 = {4d 58 4e 4f 42 55 47 4d 41 47}
		$s1 = "block.blq" wide

	condition:
		( uint16be( 0 ) == 0x4d5a ) and filesize > 100KB and filesize < 1MB and 2 of them
}

Strings (2 patterns)

IdentifierTypeValueModifiers
$s2hex{4d 58 4e 4f 42 55 47 4d 41 47}
$s1text"block.blq"wide

Condition

( uint16be( 0 ) == 0x4d5a ) and filesize > 100KB and filesize < 1MB and 2 of them

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must be smaller than 1MB (a cheap guard that skips large files).
  • The file must be larger than 100KB.
  • At least 2 patterns in the rule must match.

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References

Sample hashes

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

  • 00df0a1f037e24ff1528d524fb7398735e2c3e0a9995a9f95a5293b04748f06e

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: 891f182e-8a7a-4d0c-a481-62c198bb901b

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE

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