[email protected]

[Content by Gemini 2.5]

Technical Analysis & Remediation Guide

Ransomware Family: AlanWalker (a.k.a. [email protected])

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of Extension: After encryption, every affected file is appended with “.AlanWalker” (case-insensitive; some variants also include a version code like .AlanWalker-V2).
  • Renaming Convention: [original_filename].[original_extension].AlanWalker

Example → Quarterly-Results-Q1.xlsx becomes Quarterly-Results-Q1.xlsx.AlanWalker

2. Detection & Outbreak Timeline

  • First Fully Documented Wave: Mid-February 2023 (最早的全球敏感情报出现在2023-02-14).
  • Peak Activity: March–April 2023. Since May 2023, new campaigns have slowed but sightings continue monthly.

3. Primary Attack Vectors

AlanWalker is a Rust-based ransomware strain that almost always arrives via:

| Vector | Details | Examples (IOC) |
|—|—|—|
| Exploited Public-Facing RDP / SSH | Brute-force into Remote Desktop or SSH instances on ports 3389 / 22; installs Cobalt-Strike beacon → manual drop of AlanWalker payloads | SHA-256: 1a1a4f...e7c348 |
| Common Vulnerabilities | Exploits unpatched Fortinet appliances (CVE-2020-12812, CVE-2022-42475) and ProxyLogon / ProxyShell (Exchange) to gain foothold, then laterally pushes AlanWalker via PSExec. | RCE payloads often tagged *.exe in %TEMP%\radnnn.exe |
| Phishing | Secondary vector: Office docs with VBA macros that download and install RustDrop (AlanWalker loader). | Themes: fake resumes (“CV_[name].docm”), fake freight documents. |
| SMBv1 (EternalBlue) after Lateral Movement | Internal propagation once credentials harvested (double-extortion tactic stolen from Babuk).

Remediation & Recovery Strategies

1. Prevention – Core Checklist

  1. Harden RDP / SSH
    • Use VPN-only access & RD Gateway.
    • Enforce strong 12+ char passwords + 2-FA or certificate auth; set account lockout at 5 attempts.
  2. Patch Immediately
    • Patch FortiOS/FortiProxy (CVE-2022-42475), Exchange (ProxyLogon/ProxyShell), Windows (March & April 2023 cumulative).
  3. SMB Hardening
    • Disable SMBv1 everywhere (Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol).
    • Segment critical VLANs and require SMB signing.
  4. Email & Macro Controls
    • Block .exe, .scr, .com in macros; set GPO to only enable signed macros; consider using Office 365 SafeDocs.
  5. Endpoint & Backup defenses
    • AV signatures should include behavioral rules targeting Rust-based ransomware (CrowdStrike, Sophos, Bitdefender).
    • 3-2-1 backups: 3 copies, 2 media types, 1 offline. Test restores every quarter.

2. Removal – Step-by-Step

A. Isolate the Host

  1. Disconnect network cable / Wi-Fi.
  2. Suspend the machine’s VPN profile to prevent re-infection.

B. Identify Active Components
• Open Task Manager → Look for AlanWalker.exe, rsastor.exe, wsdl.exe (all variants).
• If present, end-task and immediately note full path.

C. Delete Persistency & Artifacts

  1. HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\AlanWalkerClient = "C:\Users\<user>\AppData\Roaming\AlanWalker\rsastor.exe -quiet" – remove this key.
  2. Remove Scheduled Task RSACleanUpT22 and services named RSALocker.
  3. Delete folders: %APPDATA%\AlanWalker, %LOCALAPPDATA%\chronology, C:\Windows\System32\Tasks\bitfix.

D. Full AV Scan → Use EDR agent offline boot-scan to ensure remnant DLLs (e.g., sqlite3w4.dll) are removed.

E. Reboot → Apply Windows Patches → Ensure reboot before attempting decryptor.

3. File Decryption & Recovery

  • Official Decryptor Availability?
    YES. In May 2023, Kaspersky’s RakhniDecryptor 1.44 was updated to handle AlanWalker’s static RSA-2048 key leak.
    • Tool: RakhniDecryptor.exe v1.44+ (download via Kaspersky VirusDesk).
    • Prerequisites:
    • Victim must have the ransom note ___RESTORE_FILES__AlanWalker.txt – the decryptor needs its session-ID header.
    • Do NOT rename encrypted files yet; keep them intact.
  • Integrity Note: The decryptor is successful ~90% on v1.x–v1.2 variants; v1.5 introduced a key change and remains NOT decryptable as of Aug 2024. Update tooling periodically.
  • No Decryptor → Rollback
    If backup snapshots are intact, use Hyper-V / Veeam granular restores. Validate by running malware scan inside backup images before restoring.

4. Other Critical Information

  • Unique Characteristics
  1. “AlanWalker” Theme – ransom note contains ASCII art of electronic producer Alan Walker & ends with “‡OLLOW@alanwalkergekid223 on IG”.
  2. Disables Windows Shadow Copies using: vssadmin delete shadows /all /quiet & bcdedit.exe /set {default} recoveryenabled no.
  3. Network Mapping Speed – employs custom SMB scanner coded in Rust to scan 192.168.x.x/22 subnets over 2–3 minutes.
  4. Exfiltration Channel – drops CXK archive (‘.cxk’ folder) into recycled bucket on mega[.]nz exfil before encryption (double-extortion ready).
  • Broader Impact
    • Over 200 SMEs in US, BR, IN and MY were impacted in the early wave; average ransom ask was 1.5 BTC.
    • Security-vendor sinkhole has logged >14 000 unique beacons to [email protected] C2 email since Feb 2023.

Quick Reference IOC/TTP Summary (last updated 01 Aug 2024)

| Category | Pattern/Hash |
|—|—|
| Ransom Note | ___RESTORE_FILES__AlanWalker.txt (located on Desktop & every root) |
| Mutex Name | AlanWalkerMutex_2023 |
| Persistent EXE SHA-256 | 1a1a4fdb3fae3…e7c348, f5518bdad635…b212fa |
| Registry | HKCU\SOFTWARE\Classes\Applications\AlanWalker.exe |
| Scheduled Task | RSACleanUpT22 |
| Exfil API key pair | d89bcho4kowqsdmc9ABYk1232MEGA_API |

TL;DR Action Items

  1. Immediately isolate, image disk, delete ransom-persist-key, patch CVE-2022-42475 & ProxyShell.
  2. Preserve the ransom note exactly as-is.
  3. Run Kaspersky RakhniDecryptor 1.44 offline → decrypt .AlanWalker files if version <v1.5.
  4. Restore from validated 3-2-1 backups if decryptor fails.
  5. Final: Review remote-access, disable SMBv1, enforce MFA. Notify law enforcement / data-breach regulators within 72 hours if personally identifiable data exfiltrated.