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YARA · SEKOIA.IO Community

SEKOIA_Tool_Nssm_Strings

Detects nssm tool

Hack toolSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X
Author
Sekoia.io
Date
2024-09-06
Modified
2024-12-19
Score / Quality
75 / 80

What this rule detects

Detects nssm tool

Targets: Windows PE.

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

Summary generated from the rule's metadata and condition.

Rule source

tool-nssm-strings.yarDetection Rule License 1.1
rule SEKOIA_Tool_Nssm_Strings : FILE
{
	meta:
		description = "Detects nssm tool"
		author = "Sekoia.io"
		id = "fab99d44-6494-4bfc-80c0-67c45bad0425"
		date = "2024-09-06"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/tool_nssm_strings.yar#L1-L22"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		hash = "beceae2fdc4f7729a93e94ac2ccd78cc"
		logic_hash = "ca883f3ed9f510cbcd9b96ad167e9d6725341c311b023f22edcba721e801f07d"
		score = 75
		quality = 80
		tags = "FILE"
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$ = "nssm start <servicename>" wide
		$ = "nssm stop <servicename>" wide
		$ = "nssm restart <servicename>" wide
		$ = "nssm status <servicename>" wide
		$ = "nssm rotate <servicename>" wide

	condition:
		uint16be( 0 ) == 0x4d5a and all of them and filesize < 500KB
}

Strings (5 patterns)

IdentifierTypeValueModifiers
$text"nssm start <servicename>"wide
$text"nssm stop <servicename>"wide
$text"nssm restart <servicename>"wide
$text"nssm status <servicename>"wide
$text"nssm rotate <servicename>"wide

Condition

uint16be( 0 ) == 0x4d5a and all of them and filesize < 500KB

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must be smaller than 500KB (a cheap guard that skips large files).
  • All 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).

  • beceae2fdc4f7729a93e94ac2ccd78cc

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: fab99d44-6494-4bfc-80c0-67c45bad0425

Metadata

version1.0
classificationTLP:CLEAR

Tags:FILE