YARA · Signature Base (Florian Roth / Nextron)
SIGNATURE_BASE_EXPL_Cleo_Exploitation_JAVA_Payloads_Dec24_1_1
Detects characteristics of JAVA files used during Cleo software exploitation (as reported by Huntress in December 2024) - files Cli, ScSlot, Slot, SrvSlot
- Author
- Florian Roth
- Date
- 2024-12-10
- Modified
- 2024-12-12
- Score / Quality
- 75 / 85
What this rule detects
Detects characteristics of JAVA files used during Cleo software exploitation (as reported by Huntress in December 2024) - files Cli, ScSlot, Slot, SrvSlot
It defines 5 patterns (5 text, 0 hex, 0 regex).
Summary generated from the rule's metadata and condition.
Rule source
rule SIGNATURE_BASE_EXPL_Cleo_Exploitation_JAVA_Payloads_Dec24_1_1 : FILE
{
meta:
= "Detects characteristics of JAVA files used during Cleo software exploitation (as reported by Huntress in December 2024) - files Cli, ScSlot, Slot, SrvSlot"
= "Florian Roth"
= "2940ddad-3dba-594a-9111-e4741d6ff39b"
= "2024-12-10"
= "2024-12-12"
= "https://www.huntress.com/blog/threat-advisory-oh-no-cleo-cleo-software-actively-being-exploited-in-the-wild"
= "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/expl_cleo_dec24.yar#L224-L245"
= "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
= "0c57b317b572d071afd8ccdb844dd6f117e20f818c6031d7ba8adcbd32be0617"
= "85600e9310e502b3b2135f2f3cf698ae54fe362047cdf9d378dcc107e0c2fa18"
= 75
= 85
= "FILE"
strings:
$a1 = "java/lang/StringBuffer"
$x1 = "Start-Sleep 3;del " ascii
$x2 = "sleep 3;rm -f '" ascii
$x3 = "powershell -Noninteractive -EncodedCommand " ascii
$x4 = "runDelFileCmd" ascii fullword
condition:
uint16( 0 ) == 0xfeca and filesize < 50KB and $a1 and 1 of ( $x* )
}
Strings (5 patterns)
| Identifier | Type | Value | Modifiers |
|---|---|---|---|
| $a1 | text | "java/lang/StringBuffer" | |
| $x1 | text | "Start-Sleep 3;del " | ascii |
| $x2 | text | "sleep 3;rm -f '" | ascii |
| $x3 | text | "powershell -Noninteractive -EncodedCommand " | ascii |
| $x4 | text | "runDelFileCmd" | ascii fullword |
Condition
uint16( 0 ) == 0xfeca and filesize < 50KB and $a1 and 1 of ( $x* )In plain words (Heuristic)
- The file must be smaller than 50KB (a cheap guard that skips large files).
- At least 1 patterns in ( $x* ) must match.
- Pattern $a1 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).
- 0c57b317b572d071afd8ccdb844dd6f117e20f818c6031d7ba8adcbd32be0617
Licence & attribution
Author: Florian Roth
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: 2940ddad-3dba-594a-9111-e4741d6ff39b
Tags:FILE
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