YARA · Cod3nym detection-rules
COD3NYM_SUSP_OBF_NET_Reactor_Native_Stub_Jan24
Detects native packer stub for version 4.5-4.7 of .NET Reactor. A pirated copy of version 4.5 of this commercial obfuscation solution is used by various malware families like BlackBit, RedLine, AgentTesla etc.
- Author
- Jonathan Peters
- Date
- 2024-01-05
- Modified
- 2024-01-12
- Score / Quality
- 70 / 80
What this rule detects
Detects native packer stub for version 4.5-4.7 of .NET Reactor. A pirated copy of version 4.5 of this commercial obfuscation solution is used by various malware families like BlackBit, RedLine, AgentTesla etc.
Associated malware family: RedLine, Agenttesla.
Targets: Windows PE.
It defines 1 patterns (0 text, 1 hex, 0 regex). YARA modules used: pe.
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"
rule COD3NYM_SUSP_OBF_NET_Reactor_Native_Stub_Jan24
{
meta:
= "Detects native packer stub for version 4.5-4.7 of .NET Reactor. A pirated copy of version 4.5 of this commercial obfuscation solution is used by various malware families like BlackBit, RedLine, AgentTesla etc."
= "Jonathan Peters"
= "529dce88-a81d-5a98-aa6c-1f1b739ad074"
= "2024-01-05"
= "2024-01-12"
= "https://notes.netbytesec.com/2023/08/understand-ransomware-ttps-blackbit.html"
= "https://github.com/cod3nym/detection-rules//blob/86a04c4594cb48895192aad4af164f21f568c136/yara/dotnet/obf_net_reactor.yar#L3-L16"
= "https://github.com/cod3nym/detection-rules//blob/86a04c4594cb48895192aad4af164f21f568c136/LICENSE.md"
= "6e8a7adf680bede7b8429a18815c232004057607fdfbf0f4b0fb1deba71c5df7"
= "287273babd3cd6bc1986b018367317019f2249851a2c19fc83857f7ff0b90b54"
= 70
= 80
= ""
strings:
$op = {C6 44 24 18 E0 C6 44 24 19 3B C6 44 24 1A 8D C6 44 24 1B 2A C6 44 24 1C A2 C6 44 24 1D 2A C6 44 24 1E 2A C6 44 24 1F 41 C6 44 24 20 D3 C6 44 24 21 20 C6 44 24 22 64 C6 44 24 23 06 C6 44 24 24 8A C6 44 24 25 F7 C6 44 24 26 3D C6 44 24 27 9D C6 44 24 28 D9 C6 44 24 29 EE C6 44 24 2A 15 C6 44 24 2B 68 C6 44 24 2C F4 C6 44 24 2D 76 C6 44 24 2E B9 C6 44 24 2F 34 C6 44 24 30 BF C6 44 24 31 1E C6 44 24 32 E7 C6 44 24 33 78 C6 44 24 34 98 C6 44 24 35 E9 C6 44 24 36 6F C6 44 24 37 B4}
condition:
for any i in ( 0 .. pe.number_of_resources -1 ) : ( pe.resources [ i ] . name_string == "_\x00_\x00" ) and $op
}
Strings (1 patterns)
| Identifier | Type | Value | Modifiers |
|---|---|---|---|
| $op | hex | {C6 44 24 18 E0 C6 44 24 19 3B C6 44 24 1A 8D C6 44 24 1B 2A C6 44 24 1C A2 C6 44 24 1D 2A C6 44 24 1E 2A C6 44 24 1F 41 C6 44 24 20 D3 C6 44 24 21 20 C6 44 24 … |
Condition
for any i in ( 0 .. pe.number_of_resources -1 ) : ( pe.resources [ i ] . name_string == "_\x00_\x00" ) and $opIn plain words (Heuristic)
- A for-loop checks a property over several matches or items.
- Uses the pe module.
- Pattern $op must be present.
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).
- 6e8a7adf680bede7b8429a18815c232004057607fdfbf0f4b0fb1deba71c5df7
Licence & attribution
Author: Jonathan Peters
Source repository: Cod3nym detection-rules @ 86a04c4594
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: 529dce88-a81d-5a98-aa6c-1f1b739ad074
Related rules
- Suspicious / huntingSignature Base (Florian Roth / Nextron)· Florian Roth (Nextron Systems)· 2022-09-17
- MalwareESET malware-ioc· ESET Research· 2022-10-11
- MalwareESET malware-ioc· ESET Research· 2022-10-11
- MalwareESET malware-ioc· ESET Research· 2022-10-11
- MalwareESET malware-ioc· ESET Research· 2022-10-11
- MalwareSEKOIA.IO Community· Sekoia.io· 2022-09-07
- MalwareEmbee Research· Matthew @embee_research· 2023-09-21
- MalwareEmbee Research· Matthew @ Embee_Research· 2023-08-27