YARA · SEKOIA.IO Community
SEKOIA_Infostealer_Win_Acrstealer_Str
Finds ACR Stealer standalone samples based on specific strings.
- Author
- Sekoia.io
- Date
- 2024-04-22
- Modified
- 2024-12-19
- Score / Quality
- 75 / 80
What this rule detects
Finds ACR Stealer standalone samples based on specific strings.
Associated malware family: Acr Stealer.
Targets: Windows PE.
It defines 15 patterns (15 text, 0 hex, 0 regex).
Summary generated from the rule's metadata and condition.
Rule source
infostealer-win-acrstealer-str.yarDetection Rule License 1.1
rule SEKOIA_Infostealer_Win_Acrstealer_Str : FILE
{
meta:
= "Finds ACR Stealer standalone samples based on specific strings."
= "Sekoia.io"
= "63b4d6ff-0cab-44ec-9d53-bb2612371a48"
= "2024-04-22"
= "2024-12-19"
= "https://github.com/SEKOIA-IO/Community"
= "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/infostealer_win_acrstealer_str.yar#L1-L29"
= "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
= "53d313857577b39b51a3e396c078d39a8b8ab803295b689357c3e8ea94cac9f7"
= 75
= 80
= "FILE"
= "1.0"
= "TLP:CLEAR"
strings:
$str01 = "ref.txt" ascii
$str02 = "Wininet.dll" ascii
$str03 = "Content-Type: application/octet-stream; boundary=----" ascii
$str04 = "POST" ascii
$str05 = "os_c" ascii fullword
$str06 = "en_k" ascii fullword
$str07 = "MyApp/1.0" ascii
$str08 = "/Up/b" ascii
$str09 = "Hello, World!" ascii
$str10 = "/ujs/" ascii
$str11 = "/Up/" ascii fullword
$str12 = "ostr" ascii fullword
$str13 = "brCH" ascii fullword
$str14 = "brGk" ascii fullword
$str15 = "https://steamcommunity.com/profiles/" ascii
condition:
uint16( 0 ) == 0x5A4D and 10 of them
}
Strings (15 patterns)
| Identifier | Type | Value | Modifiers |
|---|---|---|---|
| $str01 | text | "ref.txt" | ascii |
| $str02 | text | "Wininet.dll" | ascii |
| $str03 | text | "Content-Type: application/octet-stream; boundary=----" | ascii |
| $str04 | text | "POST" | ascii |
| $str05 | text | "os_c" | ascii fullword |
| $str06 | text | "en_k" | ascii fullword |
| $str07 | text | "MyApp/1.0" | ascii |
| $str08 | text | "/Up/b" | ascii |
| $str09 | text | "Hello, World!" | ascii |
| $str10 | text | "/ujs/" | ascii |
| $str11 | text | "/Up/" | ascii fullword |
| $str12 | text | "ostr" | ascii fullword |
| $str13 | text | "brCH" | ascii fullword |
| $str14 | text | "brGk" | ascii fullword |
| $str15 | text | "https://steamcommunity.com/profiles/" | ascii |
Condition
uint16( 0 ) == 0x5A4D and 10 of themIn plain words (Heuristic)
- The file must start with “MZ” — a Windows executable (PE).
- At least 10 patterns in the rule must match.
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References
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: 63b4d6ff-0cab-44ec-9d53-bb2612371a48
Metadata
| version | 1.0 |
|---|---|
| classification | TLP:CLEAR |
Tags:FILE
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