YARA · SEKOIA.IO Community
SEKOIA_Backdoor_Win_Minibus
Detect the MINIBUS backdoor used by UNC1549 since August 2023
- Author
- Sekoia.io
- Date
- 2024-02-29
- Modified
- 2024-12-19
- Score / Quality
- 75 / 80
What this rule detects
Detect the MINIBUS backdoor used by UNC1549 since August 2023
Associated malware family: Minibus.
Targets: Windows PE.
It defines 4 patterns (4 text, 0 hex, 0 regex). YARA modules used: pe, hash.
YARA-X says: warning[deprecated_field]: field `number_of_resources` is deprecated
Summary generated from the rule's metadata and condition.
Rule source
Includes the imports needed to compile it on its own.
import "pe"
import "hash"
rule SEKOIA_Backdoor_Win_Minibus : FILE
{
meta:
= "Detect the MINIBUS backdoor used by UNC1549 since August 2023"
= "Sekoia.io"
= "f88bcf15-9a9f-4d84-adc6-db1db55fe93c"
= "2024-02-29"
= "2024-12-19"
= "https://www.mandiant.com/resources/blog/suspected-iranian-unc1549-targets-israel-middle-east"
= "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/backdoor_win_minibus.yar#L4-L41"
= "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
= "57dabcc15c84c4497b3561f19a7e464fb0dfe93576f4caea88c7cd8534cb4bfd"
= 75
= 80
= "FILE"
= "1.0"
= "TLP:CLEAR"
strings:
$dll_150_1 = "TorvaldsPersist.dll"
$dll_150_2 = "FileCoAuth.exe"
$dll_50_1 = "TorvaldInitial.dll"
$dll_50_2 = "\\essential.dat"
condition:
( uint16( 0 ) == 0x5A4D and all of ( $dll_150_* ) or for any i in ( 0 .. pe.number_of_resources -1 ) : ( hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "2cf9797b1cfb5795d0fb892b7c371d506a5dd8b7c64fdc82975b3fde6d997df0" ) ) or ( uint16( 0 ) == 0x5A4D and all of ( $dll_50_* ) or for any i in ( 0 .. pe.number_of_resources -1 ) : ( hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "de3fb5d4419eb6b943872dd6e3dd93d19584ef2b158aa3158b3b09f0a9b628ef" ) )
}
Strings (4 patterns)
| Identifier | Type | Value | Modifiers |
|---|---|---|---|
| $dll_150_1 | text | "TorvaldsPersist.dll" | |
| $dll_150_2 | text | "FileCoAuth.exe" | |
| $dll_50_1 | text | "TorvaldInitial.dll" | |
| $dll_50_2 | text | "\\essential.dat" |
Condition
( uint16( 0 ) == 0x5A4D and all of ( $dll_150_* ) or for any i in ( 0 .. pe.number_of_resources -1 ) : ( hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "2cf9797b1cfb5795d0fb892b7c371d506a5dd8b7c64fdc82975b3fde6d997df0" ) ) or ( uint16( 0 ) == 0x5A4D and all of ( $dll_50_* ) or for any i in ( 0 .. pe.number_of_resources -1 ) : ( hash.sha256 ( pe.resources [ i ] . offset , pe.resources [ i ] . length ) == "de3fb5d4419eb6b943872dd6e3dd93d19584ef2b158aa3158b3b09f0a9b628ef" ) )In plain words (Heuristic)
- The file must start with “MZ” — a Windows executable (PE).
- All patterns in ( $dll_150_* ) must match.
- All patterns in ( $dll_50_* ) must match.
- A for-loop checks a property over several matches or items.
- Uses the pe module.
- Uses the hash module.
- Compares a hash of the file or a part of it.
Test this rule in your browser
Drop a file to scan it with this rule using YARA-X compiled to WebAssembly. Nothing is uploaded.
Licence & attribution
Author: Sekoia.io
Source repository: SEKOIA.IO Community @ a438a5901a
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: f88bcf15-9a9f-4d84-adc6-db1db55fe93c
Metadata
| version | 1.0 |
|---|---|
| classification | TLP:CLEAR |
Tags:FILE
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