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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_ELF_Reverseshell_Sslshell_Jun23_1

Detects reverse shell named SSLShell used in Barracuda ESG exploitation (CVE-2023-2868)

MalwareSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Florian Roth
Date
2023-06-07
Modified
2023-12-05
Score / Quality
75 / 85

What this rule detects

Detects reverse shell named SSLShell used in Barracuda ESG exploitation (CVE-2023-2868)

Targets: Linux ELF.

It defines 2 patterns (1 text, 1 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-elf-reverseshell-sslshell-jun23-1.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_ELF_Reverseshell_Sslshell_Jun23_1 : CVE_2023_2868 FILE
{
	meta:
		description = "Detects reverse shell named SSLShell used in Barracuda ESG exploitation (CVE-2023-2868)"
		author = "Florian Roth"
		id = "91b34eb7-61d2-592e-a444-249da43994ca"
		date = "2023-06-07"
		modified = "2023-12-05"
		reference = "https://www.barracuda.com/company/legal/esg-vulnerability"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/mal_lnx_barracuda_cve_2023_2868.yar#L2-L19"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "8849a3273e0362c45b4928375d196714224ec22cb1d2df5d029bf57349860347"
		logic_hash = "57e9afb2f6928656242b8257cc3b98ae3b03e38c75ad40b544e3fc6afaea794d"
		score = 75
		quality = 85
		tags = "CVE-2023-2868, FILE"

	strings:
		$sc1 = { 00 2D 63 00 2F 62 69 6E 2F 73 68 00 }
		$s1 = "SSLShell"

	condition:
		uint32be( 0 ) == 0x7f454c46 and uint16( 0x10 ) == 0x0002 and filesize < 5MB and all of them
}

Strings (2 patterns)

IdentifierTypeValueModifiers
$sc1hex{ 00 2D 63 00 2F 62 69 6E 2F 73 68 00 }
$s1text"SSLShell"

Condition

uint32be( 0 ) == 0x7f454c46 and uint16( 0x10 ) == 0x0002 and filesize < 5MB and all of them

In plain words (Heuristic)

  • The file must start with the ELF header — a Linux/Unix executable.
  • The file must be smaller than 5MB (a cheap guard that skips large files).
  • All patterns in the rule must match.

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References

Sample hashes

Hashes of samples the author lists in the rule's meta (look them up in your threat-intelligence platform).

  • 8849a3273e0362c45b4928375d196714224ec22cb1d2df5d029bf57349860347

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: 91b34eb7-61d2-592e-a444-249da43994ca

Tags:CVE_2023_2868FILE

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