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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_RANSOM_SH_Esxi_Attacks_Feb23_2

Detects script used in ransomware attacks exploiting and encrypting ESXi servers

MalwareSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Florian Roth
Date
2023-02-06
Modified
2023-12-05
Score / Quality
85 / 85

What this rule detects

Detects script used in ransomware attacks exploiting and encrypting ESXi servers

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

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-ransom-sh-esxi-attacks-feb23-2.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_RANSOM_SH_Esxi_Attacks_Feb23_2 : FILE
{
	meta:
		description = "Detects script used in ransomware attacks exploiting and encrypting ESXi servers"
		author = "Florian Roth"
		id = "d1282dee-0496-52f1-a2b7-27657ab4df8c"
		date = "2023-02-06"
		modified = "2023-12-05"
		reference = "https://dev.to/xakrume/esxiargs-encryption-malware-launches-massive-attacks-against-vmware-esxi-servers-pfe"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/mal_ransom_esxi_attacks_feb23.yar#L89-L101"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		logic_hash = "3f240784873a0239cbf61f7f420fdd72b8992d5943ffc3d4dcad43c836569f4d"
		score = 85
		quality = 85
		tags = "FILE"

	strings:
		$x1 = "echo \"START ENCRYPT: $file_e SIZE: $size_kb STEP SIZE: " ascii

	condition:
		filesize < 10KB and 1 of them
}

Strings (1 patterns)

IdentifierTypeValueModifiers
$x1text"echo \"START ENCRYPT: $file_e SIZE: $size_kb STEP SIZE: "ascii

Condition

filesize < 10KB and 1 of them

In plain words (Heuristic)

  • The file must be smaller than 10KB (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: d1282dee-0496-52f1-a2b7-27657ab4df8c

Tags:FILE

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