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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_EXPL_LOG_Commvault_CVE_2025_57791_Indicator_Shell_Drop_Aug25

Detects suspicious log lines that indicate web shell drops into the Apache root folder of a Commvault installation

ExploitSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Florian Roth
Date
2025-08-21
Modified
2026-05-15
Score / Quality
70 / 85

What this rule detects

Detects suspicious log lines that indicate web shell drops into the Apache root folder of a Commvault installation

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
expl-log-commvault-cve-2025-57791-indicator-shell-drop-aug25.yarDetection Rule License 1.1
rule SIGNATURE_BASE_EXPL_LOG_Commvault_CVE_2025_57791_Indicator_Shell_Drop_Aug25
{
	meta:
		description = "Detects suspicious log lines that indicate web shell drops into the Apache root folder of a Commvault installation"
		author = "Florian Roth"
		id = "efc7bcbc-6a38-5832-a12a-b8f9bd9125c1"
		date = "2025-08-21"
		modified = "2026-05-15"
		reference = "https://labs.watchtowr.com/guess-who-would-be-stupid-enough-to-rob-the-same-vault-twice-pre-auth-rce-chains-in-commvault/"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/expl_commvault_cve_2025_57791.yar#L81-L93"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		logic_hash = "f0e9fedba803b0cd8b1469bad7a50bf4647f7e2f786520caf5a79ac626879125"
		score = 70
		quality = 85
		tags = ""

	strings:
		$xr1 = /Results written to \[[C-Z]:\\Program Files\\Commvault\\ContentStore\\Apache\\webapps\\ROOT\\[^\\]{1,20}\.jsp\]/

	condition:
		$xr1
}

Strings (1 patterns)

IdentifierTypeValueModifiers
$xr1regex/Results written to \[[C-Z]:\\Program Files\\Commvault\\ContentStore\\Apache\\webapps\\ROOT\\[^\\]{1,20}\.jsp\]/

Condition

$xr1

In plain words (Heuristic)

  • Pattern $xr1 must be present.

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References

Licence & attribution

Author: Florian Roth

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: efc7bcbc-6a38-5832-a12a-b8f9bd9125c1

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