alka

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The ransomware uses “.alka” (lower-case) appended to the original name of every file it encrypts.
  • Renaming Convention: Files are renamed in three predictable segments:
    [original_name].[original_extension].[EMAIL].[random-hex-ID].alka
    Example: Budget2024.xlsx.id-A1B2C3D4.[[email protected]].alka
    The inserted e-mail (e.g., [email protected], [email protected]) changes from campaign to campaign but the overall pattern is consistent.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First major spikes reported April 2020 on abuse-box submissions and in malware-traffic-analysis blogs. Newer waves (inclusive of .alka) continue to be seen through 2021-2024 under the Phobos-family umbrella.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  • RDP brute force & credential stuffing — exposed 3389/TCP services without lockout policies.
  • Stolen/cracked RDP credentials purchased on cybercriminal forums.
  • Living-off-the-land lateral movement — uses wmic, PsExec, or mstsc.exe once inside domain.
  • Phishing e-mails delivering second-stage downloaders (SmokeLoader, GCleaner) that pull PHOBOS/Alka payloads.
  • Older VPN gateways (SonicWall SMA100, FortiGate SSL-VPN bugs) leveraged for initial foothold.
  • Software supply-chain backdoors – rare but documented for affiliates who purchase access via Trojanized MSP tools (AnyDesk screen-recording cracked builds).

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  1. Disable RDP on perimeter—secure behind VPN with MFA or adapt Zero-Trust remote access.
  2. Force Azure/Microsoft Entra MFA on every privileged account (local admin, domain admin).
  3. Immediate patching for 2020-era vulnerabilities the strain exploits (CVE-2020-1472, CVE-2019-19781, CVE-2020-0688).
  4. EDR/NGAV with behavioral detection (memory injection defense) and exploit-guard enabled for Living-off-the-Land binaries (wmic, powershell, etc.).
  5. Network segmentation — block lateral SMB traffic; consider micro-segmentation on user VLANs.
  6. Immutable, offline backups (Veeam hardened-repo, Windows Server Azure Stack HCI with cloud tier).
  7. E-mail hygiene—configure SPF, DKIM, DMARC, attachment sandboxing.
  8. Create and test a ransomware run-book including playbooks for RDP saturation alerts, password-spray IP blocks, and SOC escalation matrix.

2. Removal

  • Infection Cleanup (step-by-step):
  1. Immediately isolate the host(s). Pull the cable or disable NIC but keep HDDs powered for forensics.
  2. Power-off remaining clean machines that have share access to help prevent residual encryption loops.
  3. Collect volatile memory (winpmem.exe → raw.aff4) before shutdown for incident response.
  4. Boot infected workstation/server from a known-clean Windows PE or recovery ISO.
  5. Enumerate persistence. Alka hides in:
    • C:\ProgramData\svc-host.exe
    • Registry HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce\svc-service
    • Scheduled task WindowsServiceUpdate
  6. Delete identifiers above plus the payload.
  7. Run definition-updated reputable AV/EDR scan to sweep remnants.
  8. Change ALL domain passwords in post-intrusion rotation; revoke Kerberos tickets (nltest /sc_change_pwd).
  9. Integrity-check GPO objects (LDAP editor) for unwanted startup scripts pushed by intruders.
  10. Restore from backups only after confirming lateral movement/attack-hands are purged.
  11. Legal/communications step: preserve all forensics for IR team and law-enforcement chain-of-custody.

3. File Decryption & Recovery

  • Recovery Feasibility: Alka/PHOBOS encrypts with AES-256 + RSA-2048 or RSA-4096.
    — NO public universal decryptor exists
    — Brute-force infeasible (modern RSA key length).
    Possible under three narrow scenarios:
    a) Shadow-copies were left—run Windows vssadmin list shadows or ShadowExplorer; automate cleanup may have failed.
    b) Execution trace shows a weak random seeding flaw in an older builder (rare, investigate with forensic memory dump).
    c) Law-enforcement seizes servers and victims receive keys (PHOBOS affiliate busts in March 2023, but only four out of ~800 keys released).
    Therefore, primary recovery path is immutable or off-line backups.

  • Essential Tools/Patches:

  • Patch MS Exchange (2020-2023 cumulative updates) and Windows systems.

  • Apply SMBv1 disable via GPO and enforce SMB signing.

  • Third-party decryptor substitutes like Stop/Djvu repair utilities do not work on Alka — avoid fraud downloads.

  • Use STOPDecrypter (a valid tool, but DO NOT apply, just verify its datasets) to cross-check ID比对—if your variant ID ends in “t1” it is NOT Alka.

4. Other Critical Information

  • Additional Precautions:

  • Alka maps double-extension avoidance (e.g. keeps “.docx” inside filename) to not alert those relying on simple filename scans.

  • Drops “info.hta” and “info.txt” ransom notes in every folder, but also encrypts “README.TXT” inside nested shares (network remap risk).

  • Logs its encryption progress in %SystemRoot%\Logs\server.log—retain the file; contains an asset count for incident severity scoping.

  • Group Mario campaign tags some samples, indicating a separate geographic affiliate often targeting healthcare (U.S., Germany).

  • Host-based bypass of BCDedit-safe-mode – script issues bcdedit /set safeboot network then reboots; hence safe-mode isolation is thwarted.

  • Broader Impact:

  • Aligns with Ransomware-as-a-Service (RaaS) PHOBOS ecosystem—affiliates paid 70 % of ransom and allowed unlimited victim size.

  • 2022-2023 attacks on state municipalities in the Midwest (public documents) doubled negotiation demands above $800k in BTC.

  • Contributed to NCSC Netherlands Alert “AKBA” series, advising laser focus on threat-actor “EssayCorp” infrastructure.

Staying vigilant around exposed RDP accounts—especially combinations floating from credential-stuffing lists—remains the cornerstone defense against future **Alka infections.