YARA · SEKOIA.IO Community
SEKOIA_Apt_Aptc60_Downloader_Strings
Detects a simple downloader abusing wlrmdr.exe and used by APT-C-60
- Author
- Sekoia.io
- Date
- 2024-09-05
- Modified
- 2024-12-19
- Score / Quality
- 75 / 80
What this rule detects
Detects a simple downloader abusing wlrmdr.exe and used by APT-C-60
Targets: Windows PE.
It defines 4 patterns (4 text, 0 hex, 0 regex).
Summary generated from the rule's metadata and condition.
Rule source
rule SEKOIA_Apt_Aptc60_Downloader_Strings : FILE
{
meta:
= "Detects a simple downloader abusing wlrmdr.exe and used by APT-C-60"
= "Sekoia.io"
= "02fd6d5b-7211-46cc-bcff-ab5d78e459c0"
= "2024-09-05"
= "2024-12-19"
= "https://github.com/SEKOIA-IO/Community"
= "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/apt_aptc60_downloader_strings.yar#L1-L20"
= "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
= "b14ef85a60ac71c669cc960bdf580144"
= "f05480834e6d91a852a190a2ecec05aaea1affa8a605a56c80962a9fbfc8f0c0"
= 75
= 80
= "FILE"
= "1.0"
= "TLP:CLEAR"
strings:
$ = "mydllmain" fullword
$ = "-s 3600 -f 0 -t _ -m _ -a 11 -u" wide
$ = "WlrMakeService" wide
$ = "Trigger1" wide
condition:
uint16be( 0 ) == 0x4d5a and all of them and filesize < 500KB
}
Strings (4 patterns)
| Identifier | Type | Value | Modifiers |
|---|---|---|---|
| $ | text | "mydllmain" | fullword |
| $ | text | "-s 3600 -f 0 -t _ -m _ -a 11 -u" | wide |
| $ | text | "WlrMakeService" | wide |
| $ | text | "Trigger1" | wide |
Condition
uint16be( 0 ) == 0x4d5a and all of them and filesize < 500KBIn plain words (Heuristic)
- The file must start with “MZ” — a Windows executable (PE).
- The file must be smaller than 500KB (a cheap guard that skips large files).
- 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.
References
Sample hashes
Hashes of samples the author lists in the rule's meta (look them up in your threat-intelligence platform).
- b14ef85a60ac71c669cc960bdf580144
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: 02fd6d5b-7211-46cc-bcff-ab5d78e459c0
Metadata
| version | 1.0 |
|---|---|
| classification | TLP:CLEAR |
Tags:FILE
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