YARA · Signature Base (Florian Roth / Nextron)
SIGNATURE_BASE_EXPL_CVE_2021_1647_Apr21_1
Detects samples that exploit CVE-2021-1647
- 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
rule SIGNATURE_BASE_EXPL_CVE_2021_1647_Apr21_1 : CVE_2021_1647 FILE
{
meta:
= "Detects samples that exploit CVE-2021-1647"
= "Arkbird_SOLG"
= "ecce018e-1bee-5374-b6c8-984c2a8c2530"
= "2021-05-04"
= "2023-12-05"
= "https://attackerkb.com/topics/DzXZpEuBeP/cve-2021-1647-microsoft-windows-defender-zero-day-vulnerability"
= "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/expl_cve_2021_1647.yar#L2-L18"
= "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
= "6e1e9fa0334d8f1f5d0e3a160ba65441f0656d1f1c99f8a9f1ae4b1b1bf7d788"
= "9eaea8a56c47524f6d6b2e2bb72d035c1aa782a4f069ef9df92a0af5c6ee612b"
= "db0e53c9db41d4de21f4bbf1f60d977f5d935239d3fce8b902e8ef0082796cc7"
= "24d9ff44affea06435829507e8e6cb4b659468aa2af510031ed963caf5a6d77a"
= "b0e1809ba10e5ea624e1c4d2e948c928c590b40e6315def8cb1216930ead8579"
= 75
= 85
= "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)
| Identifier | Type | Value | Modifiers |
|---|---|---|---|
| $seq1 | hex | { 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 … | |
| $seq2 | hex | { 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 themIn 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.
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)
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
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