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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_LOG_EXPL_Adselfservice_CVE_2021_40539_ADSLOG_Sep21

Detects suspicious log lines produeced during the exploitation of ADSelfService vulnerability CVE-2021-40539

ExploitSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Florian Roth (Nextron Systems)
Date
2021-09-20
Modified
2023-12-05
Score / Quality
70 / 85

What this rule detects

Detects suspicious log lines produeced during the exploitation of ADSelfService vulnerability CVE-2021-40539

It defines 1 patterns (1 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
log-expl-adselfservice-cve-2021-40539-adslog-sep21.yarDetection Rule License 1.1
rule SIGNATURE_BASE_LOG_EXPL_Adselfservice_CVE_2021_40539_ADSLOG_Sep21 : LOG CVE_2021_40539 FILE
{
	meta:
		description = "Detects suspicious log lines produeced during the exploitation of ADSelfService vulnerability CVE-2021-40539"
		author = "Florian Roth (Nextron Systems)"
		id = "156317c6-e726-506d-8b07-4f74dae2807f"
		date = "2021-09-20"
		modified = "2023-12-05"
		reference = "https://us-cert.cisa.gov/ncas/alerts/aa21-259a"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/expl_adselfservice_cve_2021_40539.yar#L2-L14"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		logic_hash = "49b7857187c15f48e928747266adca44c227964cef72914616ea269b0e88fe73"
		score = 70
		quality = 85
		tags = "LOG, CVE-2021-40539, FILE"

	strings:
		$x1 = "Java traceback errors that include references to NullPointerException in addSmartCardConfig or getSmartCardConfig" ascii wide

	condition:
		filesize < 50MB and 1 of them
}

Strings (1 patterns)

IdentifierTypeValueModifiers
$x1text"Java traceback errors that include references to NullPointerException in addSmartCardConfig or getSmartCardConfig"ascii wide

Condition

filesize < 50MB and 1 of them

In plain words (Heuristic)

  • The file must be smaller than 50MB (a cheap guard that skips large files).
  • At least 1 patterns in the rule must match.

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References

Licence & attribution

Author: Florian Roth (Nextron Systems)

Source repository: Signature Base (Florian Roth / Nextron) @ 94a1c48d7a

Licence: Detection Rule License 1.1 (repository licence)

Original rule

Mirrored via YARA Forge 20260927, which prefixes rule names with the source and adds normalised meta fields.

Rule id: 156317c6-e726-506d-8b07-4f74dae2807f

Tags:LOGCVE_2021_40539FILE

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