Skip to content

YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_EXPL_CVE_2021_1647_Apr21_1

Detects samples that exploit CVE-2021-1647

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

What this rule detects

Detects samples that exploit CVE-2021-1647

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

Summary generated from the rule's metadata and condition.

Rule source

expl-cve-2021-1647-apr21-1.yarDetection Rule License 1.1
rule SIGNATURE_BASE_EXPL_CVE_2021_1647_Apr21_1 : CVE_2021_1647 FILE
{
	meta:
		description = "Detects samples that exploit CVE-2021-1647"
		author = "Arkbird_SOLG"
		id = "ecce018e-1bee-5374-b6c8-984c2a8c2530"
		date = "2021-05-04"
		modified = "2023-12-05"
		reference = "https://attackerkb.com/topics/DzXZpEuBeP/cve-2021-1647-microsoft-windows-defender-zero-day-vulnerability"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/expl_cve_2021_1647.yar#L2-L18"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "6e1e9fa0334d8f1f5d0e3a160ba65441f0656d1f1c99f8a9f1ae4b1b1bf7d788"
		hash = "9eaea8a56c47524f6d6b2e2bb72d035c1aa782a4f069ef9df92a0af5c6ee612b"
		hash = "db0e53c9db41d4de21f4bbf1f60d977f5d935239d3fce8b902e8ef0082796cc7"
		hash = "24d9ff44affea06435829507e8e6cb4b659468aa2af510031ed963caf5a6d77a"
		logic_hash = "b0e1809ba10e5ea624e1c4d2e948c928c590b40e6315def8cb1216930ead8579"
		score = 75
		quality = 85
		tags = "CVE-2021-1647, FILE"

	strings:
		$seq1 = { 83 7d ec 01 0f 8e fe 76 ff ff 83 45 f4 01 83 7d f4 01 0f 8e e4 76 ff ff 8b 45 e4 89 04 24 e8 12 74 ff ff 83 ec 04 a1 [2] 01 b1 85 c0 75 0e 8b 45 e4 89 04 24 e8 fb 73 ff ff 83 ec 04 a1 28 ?? 01 b1 c7 44 24 04 00 00 00 00 c7 04 24 00 00 00 00 ff d0 83 ec 08 b8 00 00 00 00 c9 c2 04 00 55 89 e5 83 ec 10 c7 45 f4 00 ?? 01 70 8b 45 08 83 e8 01 a3 70 ?? 01 b1 c7 05 74 ?? 01 b1 00 00 00 00 c7 05 a0 ?? 02 b1 00 00 00 00 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 83 e0 fe 89 c2 a1 [2] 01 b1 29 c2 89 d0 25 ff 0f 00 00 a3 5c ?? 01 b1 a1 74 ?? 01 b1 a3 a0 ?? 02 b1 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 d1 e8 83 c0 01 a3 74 ?? 01 b1 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 83 e0 fe 89 c2 a1 [2] 01 b1 29 c2 89 d0 25 ff 0f 00 00 a3 5c ?? 01 b1 a1 74 ?? 01 b1 a3 a0 ?? 02 b1 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 d1 e8 83 c0 01 a3 74 ?? 01 b1 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 83 e0 fe 89 c2 a1 [2] 01 b1 29 c2 89 d0 25 ff 0f 00 00 a3 5c ?? 01 b1 a1 74 ?? 01 b1 a3 a0 ?? 02 b1 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 d1 e8 83 c0 01 a3 74 ?? 01 b1 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 83 e0 fe 89 c2 a1 [2] 01 b1 29 c2 89 }
		$seq2 = { a1 74 ?? 01 b1 83 e8 01 83 e0 01 85 c0 74 0e 8b 15 5c ?? 01 b1 8b 45 f4 01 d0 89 45 fc 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 83 e0 fe 89 c2 a1 [2] 01 b1 29 c2 89 d0 25 ff 0f 00 00 a3 5c ?? 01 b1 a1 74 ?? 01 b1 a3 a0 ?? 02 b1 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 d1 e8 83 c0 01 a3 74 ?? 01 b1 83 7d 0c 00 74 1d a1 74 ?? 01 b1 83 e8 01 83 e0 01 85 c0 74 0e 8b 15 5c ?? 01 b1 8b 45 f4 01 d0 89 45 fc 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 83 e0 fe 89 c2 a1 [2] 01 b1 29 c2 89 d0 25 ff 0f 00 00 a3 5c ?? 01 b1 a1 74 ?? 01 b1 a3 a0 ?? 02 b1 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 d1 e8 83 c0 01 a3 74 ?? 01 b1 83 7d 0c 00 74 1d a1 74 ?? 01 b1 83 e8 01 83 e0 01 85 c0 74 0e 8b 15 5c ?? 01 b1 8b 45 f4 01 d0 89 45 fc 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 83 e0 fe 89 c2 a1 [2] 01 b1 29 c2 89 d0 25 ff 0f 00 00 a3 5c ?? 01 b1 a1 74 ?? 01 b1 a3 a0 ?? 02 b1 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 d1 e8 83 c0 01 a3 74 ?? 01 b1 83 7d 0c 00 75 0e 8b 15 5c ?? 01 b1 8b 45 f4 01 d0 89 45 fc c7 45 f8 00 00 00 00 eb 19 8b 45 f8 05 e2 ff ff 7f 8d 14 00 8b 45 fc 01 d0 66 c7 00 01 00 83 45 f8 01 83 7d f8 3b 7e e1 8b 45 fc }

	condition:
		filesize > 10KB and filesize < 10000KB and all of them
}

Strings (2 patterns)

IdentifierTypeValueModifiers
$seq1hex{ 83 7d ec 01 0f 8e fe 76 ff ff 83 45 f4 01 83 7d f4 01 0f 8e e4 76 ff ff 8b 45 e4 89 04 24 e8 12 74 ff ff 83 ec 04 a1 [2] 01 b1 85 c0 75 0e 8b 45 e4 89 04 24 e …
$seq2hex{ a1 74 ?? 01 b1 83 e8 01 83 e0 01 85 c0 74 0e 8b 15 5c ?? 01 b1 8b 45 f4 01 d0 89 45 fc 8b 15 70 ?? 01 b1 a1 74 ?? 01 b1 01 d0 83 e0 fe 89 c2 a1 [2] 01 b1 29 c …

Condition

filesize > 10KB and filesize < 10000KB and all of them

In plain words (Heuristic)

  • The file must be smaller than 10000KB (a cheap guard that skips large files).
  • The file must be larger than 10KB.
  • All patterns in the rule must match.

Test this rule in your browser

Drop a file to scan it with this rule using YARA-X compiled to WebAssembly. Nothing is uploaded.

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

Open in editor

References

Sample hashes

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

  • 6e1e9fa0334d8f1f5d0e3a160ba65441f0656d1f1c99f8a9f1ae4b1b1bf7d788
  • 9eaea8a56c47524f6d6b2e2bb72d035c1aa782a4f069ef9df92a0af5c6ee612b
  • db0e53c9db41d4de21f4bbf1f60d977f5d935239d3fce8b902e8ef0082796cc7
  • 24d9ff44affea06435829507e8e6cb4b659468aa2af510031ed963caf5a6d77a

Licence & attribution

Author: Arkbird_SOLG

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: ecce018e-1bee-5374-b6c8-984c2a8c2530

Tags:CVE_2021_1647FILE