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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_SUSP_Doc_Wordxmlrels_May22

Detects a suspicious pattern in docx document.xml.rels file as seen in CVE-2022-30190 / Follina exploitation

Suspicious / huntingSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Tobias Michalski, Christian Burkard, Wojciech Cieslak
Date
2022-05-30
Modified
2022-06-20
Score / Quality
70 / 85

What this rule detects

Detects a suspicious pattern in docx document.xml.rels file as seen in CVE-2022-30190 / Follina exploitation

It defines 6 patterns (6 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
susp-doc-wordxmlrels-may22.yarDetection Rule License 1.1
rule SIGNATURE_BASE_SUSP_Doc_Wordxmlrels_May22 : CVE_2022_30190 FILE
{
	meta:
		description = "Detects a suspicious pattern in docx document.xml.rels file as seen in CVE-2022-30190 / Follina exploitation"
		author = "Tobias Michalski, Christian Burkard, Wojciech Cieslak"
		id = "304c4816-b2f6-5319-9fe9-8f74bdb82ad0"
		date = "2022-05-30"
		modified = "2022-06-20"
		reference = "https://doublepulsar.com/follina-a-microsoft-office-code-execution-vulnerability-1a47fce5629e"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/gen_doc_follina.yar#L39-L61"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "62f262d180a5a48f89be19369a8425bec596bc6a02ed23100424930791ae3df0"
		logic_hash = "c9846f8c2c1724792de14ab4de0064f951a8faaf01cc27d873e600f29d59c842"
		score = 70
		quality = 85
		tags = "CVE-2022-30190, FILE"

	strings:
		$a1 = "<Relationships" ascii
		$a2 = "TargetMode=\"External\"" ascii
		$x1 = ".html!" ascii
		$x2 = ".htm!" ascii
		$x3 = "%2E%68%74%6D%6C%21" ascii
		$x4 = "%2E%68%74%6D%21" ascii

	condition:
		filesize < 50KB and all of ( $a* ) and 1 of ( $x* )
}

Strings (6 patterns)

IdentifierTypeValueModifiers
$a1text"<Relationships"ascii
$a2text"TargetMode=\"External\""ascii
$x1text".html!"ascii
$x2text".htm!"ascii
$x3text"%2E%68%74%6D%6C%21"ascii
$x4text"%2E%68%74%6D%21"ascii

Condition

filesize < 50KB and all of ( $a* ) and 1 of ( $x* )

In plain words (Heuristic)

  • The file must be smaller than 50KB (a cheap guard that skips large files).
  • All patterns in ( $a* ) must match.
  • At least 1 patterns in ( $x* ) 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).

  • 62f262d180a5a48f89be19369a8425bec596bc6a02ed23100424930791ae3df0

Licence & attribution

Author: Tobias Michalski, Christian Burkard, Wojciech Cieslak

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: 304c4816-b2f6-5319-9fe9-8f74bdb82ad0

Tags:CVE_2022_30190FILE

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