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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_Passwordstate_Moserware_Backdoor_Apr21_1

Detects backdoor used in Passwordstate incident

MalwareSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Florian Roth (Nextron Systems)
Date
2021-04-25
Modified
2023-12-05
Score / Quality
75 / 85

What this rule detects

Detects backdoor used in Passwordstate incident

Targets: Windows PE.

It defines 7 patterns (4 text, 3 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-passwordstate-moserware-backdoor-apr21-1.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_Passwordstate_Moserware_Backdoor_Apr21_1 : FILE
{
	meta:
		description = "Detects backdoor used in Passwordstate incident"
		author = "Florian Roth (Nextron Systems)"
		id = "061de3ae-c404-5e4a-a16b-b3b208b1ae7f"
		date = "2021-04-25"
		modified = "2023-12-05"
		reference = "https://thehackernews.com/2021/04/passwordstate-password-manager-update.html"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/mal_passwordstate_backdoor.yar#L1-L24"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "c2169ab4a39220d21709964d57e2eafe4b68c115061cbb64507cfbbddbe635c6"
		hash = "f23f9c2aaf94147b2c5d4b39b56514cd67102d3293bdef85101e2c05ee1c3bf9"
		logic_hash = "46bf5b7f4f75997535742021d1d5c2129daae0b3836c08383058e5e5b8e27d93"
		score = 75
		quality = 85
		tags = "FILE"

	strings:
		$x1 = "https://passwordstate-18ed2.kxcdn.com" wide
		$s1 = " ProxyUserName, ProxyPassword FROM [SystemSettings]" wide fullword
		$s2 = "PasswordstateService.Passwordstate.Crypto" wide
		$s3 = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.128 Safari" wide fullword
		$op1 = { 00 4c 00 4e 00 43 00 4c 00 49 00 31 00 31 00 3b 00 00 17 }
		$op2 = { 4c 00 49 00 31 00 31 00 3b 00 00 17 50 00 72 00 }
		$op3 = { 61 00 74 00 65 00 2d 00 31 00 38 00 65 00 64 00 32 00 2e 00 6b 00 78 00 }

	condition:
		uint16( 0 ) == 0x5a4d and filesize < 200KB and 1 of ( $x* ) or 3 of them
}

Strings (7 patterns)

IdentifierTypeValueModifiers
$x1text"https://passwordstate-18ed2.kxcdn.com"wide
$s1text" ProxyUserName, ProxyPassword FROM [SystemSettings]"wide fullword
$s2text"PasswordstateService.Passwordstate.Crypto"wide
$s3text"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.128 Safari"wide fullword
$op1hex{ 00 4c 00 4e 00 43 00 4c 00 49 00 31 00 31 00 3b 00 00 17 }
$op2hex{ 4c 00 49 00 31 00 31 00 3b 00 00 17 50 00 72 00 }
$op3hex{ 61 00 74 00 65 00 2d 00 31 00 38 00 65 00 64 00 32 00 2e 00 6b 00 78 00 }

Condition

uint16( 0 ) == 0x5a4d and filesize < 200KB and 1 of ( $x* ) or 3 of them

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • The file must be smaller than 200KB (a cheap guard that skips large files).
  • At least 1 patterns in ( $x* ) must match.
  • At least 3 patterns in the rule must match.

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

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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).

  • c2169ab4a39220d21709964d57e2eafe4b68c115061cbb64507cfbbddbe635c6
  • f23f9c2aaf94147b2c5d4b39b56514cd67102d3293bdef85101e2c05ee1c3bf9

Licence & attribution

Author: Florian Roth (Nextron Systems)

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: 061de3ae-c404-5e4a-a16b-b3b208b1ae7f

Tags:FILE

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