ByteCode_MSIL_Ransomware_ZeroLocker

YARA-2025-0254 Critical general Active

Yara rule that detects ZeroLocker ransomware.

ByteCode_MSIL_Ransomware_ZeroLocker.yar Valid Syntax

rule ByteCode_MSIL_Ransomware_ZeroLocker : tc_detection malicious
{
    meta:

        author              = "ReversingLabs"

        source              = "ReversingLabs"
        status              = "RELEASED"
        sharing             = "TLP:WHITE"
        category            = "MALWARE"
        malware             = "ZEROLOCKER"
        description         = "Yara rule that detects ZeroLocker ransomware."

        tc_detection_type   = "Ransomware"
        tc_detection_name   = "ZeroLocker"
        tc_detection_factor = 5

    strings:
        $encrypt_routine_1 = {
            00 28 5B 00 00 0A 20 ?? 07 00 00 28 60 00 00 06 13 09 20 ?? 07 00 00 28 60 00 00 06 13 
            0B 02 03 20 ?? 07 00 00 28 60 00 00 06 20 ?? 07 00 00 28 60 00 00 06 73 ?? 00 00 0A 7D 
            1B 00 00 04 20 ?? 07 00 00 28 60 00 00 06 13 0B 02 04 20 ?? 07 00 00 28 60 00 00 06 20 
            ?? 07 00 00 28 60 00 00 06 73 ?? 00 00 0A 7D 1C 00 00 04 20 ?? 07 00 00 28 60 00 00 06 
            13 0B 02 7B 1C 00 00 04 20 ?? 07 00 00 28 60 00 00 06 6A 6F ?? 00 00 0A 00 20 ?? 07 00 
            00 28 60 00 00 06 13 0B 20 ?? 07 00 00 28 60 00 00 06 8D 1E 00 00 01 0A 20 ?? 07 00 00 
            28 60 00 00 06 13 0B 20 ?? 07 00 00 28 60 00 00 06 6A 13 04 20 ?? 07 00 00 28 60 00 00 
            06 13 0B 02 7B 1B 00 00 04 6F ?? 00 00 0A [0-2] 13 05 20 ?? 07 00 00 28 60 00 00 06 13 
            0B 73 ?? 00 00 0A 0C 20 ?? 07 00 00 28 60 00 00 06 13 0B 00 0E 05 20 ?? 07 00 00 28 60 
            00 00 06 59 13 0C 11 0C 45 02 00 00 00 02 00 00 00 ?? 00 00 00 2B ?? 00 20 ?? 07 00 00 
            28 60 00 00 06 13 0B 02 7B 1C 00 00 04 08 05 0E 04 6F ?? 00 00 0A [0-2] 20 ?? 07 00 00 
            28 60 00 00 06 73 ?? 00 00 0A 0B 2B ?? 00 20 ?? 07 00 00 28 60 00 00 06 13 0B 02 7B 1C 
            00 00 04 08 05 0E 04 6F ?? 00 00 0A [0-2] 20 ?? 07 00 00 28 60 00 00 06 73 ?? 00 00 0A 
            0B 00 2B 62 20 ?? 07 00 00 28 60 00 00 06 13 0B 02 7B 1B 00 00 04 06 20 ?? 07 00 00 28 
            60 00 00 06 20 ?? 07 00 00 28 60 00 00 06 6F ?? 00 00 0A [0-2] 0D 20 ?? 07 00 00 28 60
        }

        $encrypt_routine_2 = {
            00 00 06 13 0B 07 06 20 ?? 07 00 00 28 60 00 00 06 09 6F ?? 00 00 0A 00 20 ?? 07 00 00 
            28 60 00 00 06 13 0B 11 04 09 6A D6 13 04 00 20 ?? 07 00 00 28 60 00 00 06 13 0B 11 04 
            11 05 FE 04 13 0D 11 0D 2D 86 ?? 45 01 00 00 00 F6 FF FF FF 17 2D 06 D0 4F 00 00 06 26 
            20 ?? 07 00 00 28 60 00 00 06 13 0B 07 6F ?? 00 00 0A 00 20 ?? 07 00 00 28 60 00 00 06 
            13 0B 02 7B 1B 00 00 04 6F ?? 00 00 0A 00 20 ?? 07 00 00 28 60 00 00 06 13 0B 02 7B 1C 
            00 00 04 6F ?? 00 00 0A 00 20 ?? 07 00 00 28 60 00 00 06 13 0B 0E 05 20 ?? 07 00 00 28 
            60 00 00 06 FE 01 13 0D 11 0D 2C 32 ?? 45 01 00 00 00 F6 FF FF FF 20 ?? 07 00 00 28 60 
            00 00 06 13 0B 03 73 ?? 00 00 0A 13 06 20 ?? 07 00 00 28 60 00 00 06 13 0B 11 06 6F ?? 
            00 00 0A 00 00 20 ?? 07 00 00 28 60 00 00 06 13 0B 0E 05 20 ?? 07 00 00 28 60 00 00 06 
            FE 01 13 0D 11 0D 2C ?? [0-20] 20 ?? 07 00 00 28 60 00 00 06 13 0B 03 73 ?? 00 00 0A 13 
            07 20 ?? 07 00 00 28 60 00 00 06 13 0B 11 07 6F ?? 00 00 0A 00 00 20 ?? ?? 00 00 28 60 
            00 00 06 13 0B 02 7B 1B 00 00 04 6F ?? 00 00 0A 00 20 ?? ?? 00 00 28 60 00 00 06 13 0B 
            02 7B 1C 00 00 04 6F ?? 00 00 0A 00 DD 3B 01 00 00 11 0A 2B 0D 11 0A 20 ?? ?? 00 00 28
        }

        $encrypt_routine_3 = { 
            60 00 00 06 58 20 ?? 08 00 00 28 60 00 00 06 13 0A 45 26 00 00 00 00 00 00 00 ?? FC FF 
            FF ?? FC FF FF ?? FC FF FF ?? FC FF FF ?? FC FF FF ?? FC FF FF ?? FC FF FF ?? ?? FF FF 
            ?? FD FF FF ?? FD FF FF ?? FD FF FF 00 00 00 00 ?? FD FF FF ?? FD FF FF ?? FD FF FF ?? 
            FD FF FF ?? FD FF FF ?? FD FF FF ?? ?? FF FF ?? FD FF FF ?? FD FF FF ?? FD FF FF ?? ?? 
            FF FF ?? FE FF FF ?? FE FF FF ?? FE FF FF ?? FE FF FF ?? FE FF FF ?? FE FF FF ?? FE FF 
            FF ?? FE FF FF E8 FE FF FF FC FE FF FF 10 FF FF FF 11 FF FF FF 29 FF FF FF 41 FF FF FF 
            DE 6D 11 0B 13 0A 11 09 20 ?? 08 00 00 28 60 00 00 06 30 16 ?? 45 01 00 00 00 F6 FF FF 
            FF 20 ?? 08 00 00 28 60 00 00 06 2B 02 11 09 45 02 00 00 00 00 00 00 00 11 FF FF FF DE 
            34 75 4B 00 00 01 14 FE 03 11 09 20 ?? 08 00 00 28 60 00 00 06 FE 03 5F 11 0A 20 ?? 08 
            00 00 28 60 00 00 06 FE 01 5F FE 11 74 4B 00 00 01 28 57 00 00 0A DE 93 20 ?? 08 00 00 
            28 60 00 00 06 28 ?? 00 00 0A 
        }

    condition:
        uint16(0) == 0x5A4D and
        ($encrypt_routine_1 and $encrypt_routine_2 and $encrypt_routine_3)
}

Rule Metadata

author

ReversingLabs

source

ReversingLabs

status

RELEASED

sharing

TLP:WHITE

String Definitions

{"name":"$encrypt_routine_1","value":"{\n 00 28 5B 00 00 0A 20 ?? 07 00 00 28 60 00 00 06 13 09 20 ?? 07 00 00 28 60 00 00 06 13 \n 0B 02 03 20 ?? 07 00 00 28 60 00 00 06 20 ?? 07 00 00 28 60 00 00 06 73 ?? 00 00 0A 7D \n 1B 00 00 04 20 ?? 07 00 00 28 60 00 00 06 13 0B 02 04 20 ?? 07 00 00 28 60 00 00 06 20 \n ?? 07 00 00 28 60 00 00 06 73 ?? 00 00 0A 7D 1C 00 00 04 20 ?? 07 00 00 28 60 00 00 06 \n 13 0B 02 7B 1C 00 00 04 20 ?? 07 00 00 28 60 00 00 06 6A 6F ?? 00 00 0A 00 20 ?? 07 00 \n 00 28 60 00 00 06 13 0B 20 ?? 07 00 00 28 60 00 00 06 8D 1E 00 00 01 0A 20 ?? 07 00 00 \n 28 60 00 00 06 13 0B 20 ?? 07 00 00 28 60 00 00 06 6A 13 04 20 ?? 07 00 00 28 60 00 00 \n 06 13 0B 02 7B 1B 00 00 04 6F ?? 00 00 0A [0-2] 13 05 20 ?? 07 00 00 28 60 00 00 06 13 \n 0B 73 ?? 00 00 0A 0C 20 ?? 07 00 00 28 60 00 00 06 13 0B 00 0E 05 20 ?? 07 00 00 28 60 \n 00 00 06 59 13 0C 11 0C 45 02 00 00 00 02 00 00 00 ?? 00 00 00 2B ?? 00 20 ?? 07 00 00 \n 28 60 00 00 06 13 0B 02 7B 1C 00 00 04 08 05 0E 04 6F ?? 00 00 0A [0-2] 20 ?? 07 00 00 \n 28 60 00 00 06 73 ?? 00 00 0A 0B 2B ?? 00 20 ?? 07 00 00 28 60 00 00 06 13 0B 02 7B 1C \n 00 00 04 08 05 0E 04 6F ?? 00 00 0A [0-2] 20 ?? 07 00 00 28 60 00 00 06 73 ?? 00 00 0A \n 0B 00 2B 62 20 ?? 07 00 00 28 60 00 00 06 13 0B 02 7B 1B 00 00 04 06 20 ?? 07 00 00 28 \n 60 00 00 06 20 ?? 07 00 00 28 60 00 00 06 6F ?? 00 00 0A [0-2] 0D 20 ?? 07 00 00 28 60\n }"}

{"name":"$encrypt_routine_2","value":"{\n 00 00 06 13 0B 07 06 20 ?? 07 00 00 28 60 00 00 06 09 6F ?? 00 00 0A 00 20 ?? 07 00 00 \n 28 60 00 00 06 13 0B 11 04 09 6A D6 13 04 00 20 ?? 07 00 00 28 60 00 00 06 13 0B 11 04 \n 11 05 FE 04 13 0D 11 0D 2D 86 ?? 45 01 00 00 00 F6 FF FF FF 17 2D 06 D0 4F 00 00 06 26 \n 20 ?? 07 00 00 28 60 00 00 06 13 0B 07 6F ?? 00 00 0A 00 20 ?? 07 00 00 28 60 00 00 06 \n 13 0B 02 7B 1B 00 00 04 6F ?? 00 00 0A 00 20 ?? 07 00 00 28 60 00 00 06 13 0B 02 7B 1C \n 00 00 04 6F ?? 00 00 0A 00 20 ?? 07 00 00 28 60 00 00 06 13 0B 0E 05 20 ?? 07 00 00 28 \n 60 00 00 06 FE 01 13 0D 11 0D 2C 32 ?? 45 01 00 00 00 F6 FF FF FF 20 ?? 07 00 00 28 60 \n 00 00 06 13 0B 03 73 ?? 00 00 0A 13 06 20 ?? 07 00 00 28 60 00 00 06 13 0B 11 06 6F ?? \n 00 00 0A 00 00 20 ?? 07 00 00 28 60 00 00 06 13 0B 0E 05 20 ?? 07 00 00 28 60 00 00 06 \n FE 01 13 0D 11 0D 2C ?? [0-20] 20 ?? 07 00 00 28 60 00 00 06 13 0B 03 73 ?? 00 00 0A 13 \n 07 20 ?? 07 00 00 28 60 00 00 06 13 0B 11 07 6F ?? 00 00 0A 00 00 20 ?? ?? 00 00 28 60 \n 00 00 06 13 0B 02 7B 1B 00 00 04 6F ?? 00 00 0A 00 20 ?? ?? 00 00 28 60 00 00 06 13 0B \n 02 7B 1C 00 00 04 6F ?? 00 00 0A 00 DD 3B 01 00 00 11 0A 2B 0D 11 0A 20 ?? ?? 00 00 28\n }"}

{"name":"$encrypt_routine_3","value":"{ \n 60 00 00 06 58 20 ?? 08 00 00 28 60 00 00 06 13 0A 45 26 00 00 00 00 00 00 00 ?? FC FF \n FF ?? FC FF FF ?? FC FF FF ?? FC FF FF ?? FC FF FF ?? FC FF FF ?? FC FF FF ?? ?? FF FF \n ?? FD FF FF ?? FD FF FF ?? FD FF FF 00 00 00 00 ?? FD FF FF ?? FD FF FF ?? FD FF FF ?? \n FD FF FF ?? FD FF FF ?? FD FF FF ?? ?? FF FF ?? FD FF FF ?? FD FF FF ?? FD FF FF ?? ?? \n FF FF ?? FE FF FF ?? FE FF FF ?? FE FF FF ?? FE FF FF ?? FE FF FF ?? FE FF FF ?? FE FF \n FF ?? FE FF FF E8 FE FF FF FC FE FF FF 10 FF FF FF 11 FF FF FF 29 FF FF FF 41 FF FF FF \n DE 6D 11 0B 13 0A 11 09 20 ?? 08 00 00 28 60 00 00 06 30 16 ?? 45 01 00 00 00 F6 FF FF \n FF 20 ?? 08 00 00 28 60 00 00 06 2B 02 11 09 45 02 00 00 00 00 00 00 00 11 FF FF FF DE \n 34 75 4B 00 00 01 14 FE 03 11 09 20 ?? 08 00 00 28 60 00 00 06 FE 03 5F 11 0A 20 ?? 08 \n 00 00 28 60 00 00 06 FE 01 5F FE 11 74 4B 00 00 01 28 57 00 00 0A DE 93 20 ?? 08 00 00 \n 28 60 00 00 06 28 ?? 00 00 0A \n }"}

Threat Analysis

This YARA rule is designed to detect general threats.

Severity Level: Critical

The rule uses pattern matching to identify specific byte sequences, strings, or behavioral patterns associated with malicious activity.

Detection Capabilities

File-based detection for executables and documents
Memory scanning for running processes
Network traffic analysis support

Command Line Usage

# Scan a single file
yara ByteCode_MSIL_Ransomware_ZeroLocker.yar /path/to/suspicious/file

# Scan a directory recursively
yara -r ByteCode_MSIL_Ransomware_ZeroLocker.yar /path/to/directory/

# Scan with metadata output
yara -m ByteCode_MSIL_Ransomware_ZeroLocker.yar target_file

# Scan process memory (Linux)
yara ByteCode_MSIL_Ransomware_ZeroLocker.yar /proc/[pid]/exe

Integration Examples

Python (yara-python)

import yara
rules = yara.compile(filepath='ByteCode_MSIL_Ransomware_ZeroLocker.yar')
matches = rules.match('/path/to/file')

ClamAV Integration

clamscan --yara-rules=ByteCode_MSIL_Ransomware_ZeroLocker.yar /path/to/scan

Rule Information

YARA ID

YARA-2025-0254

Author

ReversingLabs

Repository

reversinglabs_reversinglabs-yara-rules

Created

August 19, 2025

Last Updated

August 19, 2025

Last Imported

Never

Threat Intelligence

Risk Level Critical

Category general

Detection Confidence Analysis Pending

False Positive Rate Not Available

Last Seen in Wild No Data

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Export Options

Similar Rules in general

YARA-2023-0001 CRI

ByteCode_MSIL_Ransomware_ZeroLocker

Rule Metadata

Tags

String Definitions

Threat Analysis

Detection Capabilities

Command Line Usage

Integration Examples

Python (yara-python)

ClamAV Integration

Rule Information

Threat Intelligence

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Export Options

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