R3C0NST_Prolock_Malware

YARA detection rule by Frank Boldewin (@r3c0nst) · GPL-2.0

Detects Prolock malware in encrypted and decrypted mode

rule R3C0NST_Prolock_Malware: FILE {
  meta:
    description = "Detects Prolock malware in encrypted and decrypted mode"
    author      = "Frank Boldewin (@r3c0nst)"
    id          = "1440b5f5-f1e7-522e-8852-84c326858bb9"
    date        = "2020-05-17"
    modified    = "2020-05-20"
    reference   = "https://raw.githubusercontent.com/fboldewin/YARA-rules/master/Prolock.Malware.yar"
    source_url  = "https://github.com/fboldewin/YARA-rules//blob/54e9e6899b258b72074b2b4db6909257683240c2/Prolock.Malware.yar#L1-L20"
    license_url = "N/A"
    logic_hash  = "7502011eba1e36c8ec699f1b627c4980cc3009bb43c5aa5a58571330e93211ea"
    score       = 75
    quality     = 90
    tags        = "FILE"
    hash1       = "a6ded68af5a6e5cc8c1adee029347ec72da3b10a439d98f79f4b15801abd7af0"
    hash2       = "dfbd62a3d1b239601e17a5533e5cef53036647901f3fb72be76d92063e279178"

  strings:
    $DecryptionRoutine1 = { 31 04 1A 81 3C 1A 90 90 90 90 74 }
    $DecryptionRoutine2 = { 83 C3 04 81 3C 1A C4 C4 C4 C4 74 }
    $DecryptedString1   = "support981723721@protonmail.com" nocase ascii
    $DecryptedString2   = "Your files have been encrypted by ProLock Ransomware" nocase ascii
    $DecryptedString3   = "msaoyrayohnp32tcgwcanhjouetb5k54aekgnwg7dcvtgtecpumrxpqd.onion" nocase ascii
    $CryptoCode         = { B8 63 51 E1 B7 31 D2 8D BE ?? ?? ?? ?? B9 63 51 E1 B7 81 C1 B9 79 37 9E }

  condition:
    ((uint16(0) == 0x5A4D) or (uint16(0) == 0x4D42)) and filesize < 100KB and all of ($DecryptionRoutine*) or (1 of ($DecryptedString*) and $CryptoCode)
}

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

6c4eeaf2-5cf1-492e-9093-426b2d918e4e

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

[[ reason ]]

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

[[ reason ]]

What do these messages mean?

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

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