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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_APT_Sandworm_Cyclopsblink_Modified_Install_Upgrade

Detects notable strings identified within the modified install_upgrade executable, embedded within Cyclops Blink

APT / threat actorSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
NCSC
Date
2022-02-23
Modified
2023-12-05
Score / Quality
75 / 85

What this rule detects

Detects notable strings identified within the modified install_upgrade executable, embedded within Cyclops Blink

Targets: Linux ELF.

It defines 9 patterns (5 text, 4 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
apt-sandworm-cyclopsblink-modified-install-upgrade.yarDetection Rule License 1.1
rule SIGNATURE_BASE_APT_Sandworm_Cyclopsblink_Modified_Install_Upgrade : FILE
{
	meta:
		description = "Detects notable strings identified within the modified install_upgrade executable, embedded within Cyclops Blink"
		author = "NCSC"
		id = "4c4f7262-df74-5f6a-afc0-df1fcae4741c"
		date = "2022-02-23"
		modified = "2023-12-05"
		reference = "https://www.ncsc.gov.uk/news/joint-advisory-shows-new-sandworm-malware-cyclops-blink-replaces-vpnfilter"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_sandworm_cyclops_blink.yar#L57-L88"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "3adf9a59743bc5d8399f67cab5eb2daf28b9b863"
		hash = "c59bc17659daca1b1ce65b6af077f86a648ad8a8"
		hash = "7d61c0dd0cd901221a9dff9df09bb90810754f10"
		hash = "438cd40caca70cafe5ca436b36ef7d3a6321e858"
		logic_hash = "69b89dbaf3e2661f376ff1be7c19e96c82bf84fd572fea422c109f8afdd1e5aa"
		score = 75
		quality = 85
		tags = "FILE"

	strings:
		$ = "/pending/%010lu_%06d_%03d_p1"
		$ = "/pending/sysa_code_dir/test_%d_%d_%d_%d_%d_%d"
		$ = "etaonrishdlcupfm"
		$ = "/pending/WGUpgrade-dl.new"
		$ = "/pending/bin/install_upgraded"
		$ = {38 80 4C 00}
		$ = {38 80 4C 05}
		$ = {38 80 4C 04}
		$ = {3C 00 48 4D 60 00 41 43 90 09 00 00}

	condition:
		( uint32( 0 ) == 0x464c457f ) and ( 6 of them )
}

Strings (9 patterns)

IdentifierTypeValueModifiers
$text"/pending/%010lu_%06d_%03d_p1"
$text"/pending/sysa_code_dir/test_%d_%d_%d_%d_%d_%d"
$text"etaonrishdlcupfm"
$text"/pending/WGUpgrade-dl.new"
$text"/pending/bin/install_upgraded"
$hex{38 80 4C 00}
$hex{38 80 4C 05}
$hex{38 80 4C 04}
$hex{3C 00 48 4D 60 00 41 43 90 09 00 00}

Condition

( uint32( 0 ) == 0x464c457f ) and ( 6 of them )

In plain words (Heuristic)

  • The file must start with the ELF header — a Linux/Unix executable.
  • At least 6 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).

  • 3adf9a59743bc5d8399f67cab5eb2daf28b9b863
  • c59bc17659daca1b1ce65b6af077f86a648ad8a8
  • 7d61c0dd0cd901221a9dff9df09bb90810754f10
  • 438cd40caca70cafe5ca436b36ef7d3a6321e858

Licence & attribution

Author: NCSC

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: 4c4f7262-df74-5f6a-afc0-df1fcae4741c

Tags:FILE

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