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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_EXPL_Citrix_Netscaler_ADC_Forensicartifacts_CVE_2023_3519_Jul23_2

Detects forensic artifacts found after an exploitation of Citrix NetScaler ADC CVE-2023-3519

ExploitSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Florian Roth
Date
2023-07-21
Modified
2023-12-05
Score / Quality
70 / 85

What this rule detects

Detects forensic artifacts found after an exploitation of Citrix NetScaler ADC CVE-2023-3519

It defines 3 patterns (3 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
expl-citrix-netscaler-adc-forensicartifacts-cve-2023-3519-jul23-2.yarDetection Rule License 1.1
rule SIGNATURE_BASE_EXPL_Citrix_Netscaler_ADC_Forensicartifacts_CVE_2023_3519_Jul23_2 : CVE_2023_3519 FILE
{
	meta:
		description = "Detects forensic artifacts found after an exploitation of Citrix NetScaler ADC CVE-2023-3519"
		author = "Florian Roth"
		id = "471ce547-0133-5836-b9d1-02c932ecfd1e"
		date = "2023-07-21"
		modified = "2023-12-05"
		reference = "https://www.cisa.gov/sites/default/files/2023-07/aa23-201a_csa_threat_actors_exploiting_citrix-cve-2023-3519_to_implant_webshells.pdf"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/expl_citrix_netscaler_adc_exploitation_cve_2023_3519.yar#L27-L41"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		logic_hash = "48d4225d0935084003f7a98c554d7c4722a91290dfe190001da52bce332b3f7d"
		score = 70
		quality = 85
		tags = "CVE-2023-3519, FILE"

	strings:
		$s1 = "tar -czvf - /var/tmp/all.txt" ascii fullword
		$s2 = "-out /var/tmp/test.tar.gz" ascii
		$s3 = "/test.tar.gz /netscaler/"

	condition:
		filesize < 10MB and 1 of them
}

Strings (3 patterns)

IdentifierTypeValueModifiers
$s1text"tar -czvf - /var/tmp/all.txt"ascii fullword
$s2text"-out /var/tmp/test.tar.gz"ascii
$s3text"/test.tar.gz /netscaler/"

Condition

filesize < 10MB and 1 of them

In plain words (Heuristic)

  • The file must be smaller than 10MB (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

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: 471ce547-0133-5836-b9d1-02c932ecfd1e

Tags:CVE_2023_3519FILE

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