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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_EXPL_Follina_CVE_2022_30190_Msdt_Msprotocoluri_May22

Detects the malicious usage of the ms-msdt URI as seen in CVE-2022-30190 / Follina exploitation

ExploitSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Tobias Michalski, Christian Burkard
Date
2022-05-30
Modified
2022-07-18
Score / Quality
80 / 85

What this rule detects

Detects the malicious usage of the ms-msdt URI as seen in CVE-2022-30190 / Follina exploitation

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
expl-follina-cve-2022-30190-msdt-msprotocoluri-may22.yarDetection Rule License 1.1
rule SIGNATURE_BASE_EXPL_Follina_CVE_2022_30190_Msdt_Msprotocoluri_May22 : CVE_2022_30190 FILE
{
	meta:
		description = "Detects the malicious usage of the ms-msdt URI as seen in CVE-2022-30190 / Follina exploitation"
		author = "Tobias Michalski, Christian Burkard"
		id = "62e67c25-a420-5dac-9d1c-b0648ea6b574"
		date = "2022-05-30"
		modified = "2022-07-18"
		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#L81-L99"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "4a24048f81afbe9fb62e7a6a49adbd1faf41f266b5f9feecdceb567aec096784"
		hash = "778cbb0ee4afffca6a0b788a97bc2f4855ceb69ddc5eaa230acfa2834e1aeb07"
		logic_hash = "d56820737951f97606749c74025589e6a8ecbe70cfff069492368b2ba8528a7d"
		score = 80
		quality = 85
		tags = "CVE-2022-30190, FILE"

	strings:
		$re1 = /location\.href\s{0,20}=\s{0,20}"ms-msdt:/
		$a1 = "%6D%73%2D%6D%73%64%74%3A%2F" ascii

	condition:
		filesize > 3KB and filesize < 100KB and 1 of them
}

Strings (2 patterns)

IdentifierTypeValueModifiers
$re1regex/location\.href\s{0,20}=\s{0,20}"ms-msdt:/
$a1text"%6D%73%2D%6D%73%64%74%3A%2F"ascii

Condition

filesize > 3KB and filesize < 100KB and 1 of them

In plain words (Heuristic)

  • The file must be smaller than 100KB (a cheap guard that skips large files).
  • The file must be larger than 3KB.
  • At least 1 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).

  • 4a24048f81afbe9fb62e7a6a49adbd1faf41f266b5f9feecdceb567aec096784
  • 778cbb0ee4afffca6a0b788a97bc2f4855ceb69ddc5eaa230acfa2834e1aeb07

Licence & attribution

Author: Tobias Michalski, Christian Burkard

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: 62e67c25-a420-5dac-9d1c-b0648ea6b574

Tags:CVE_2022_30190FILE

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