ehehehx12

[Content by Gemini 2.5]

Ransomware Resource Sheet

Variant tracked by extension: .ehehehx12 (updated 06-Dec-2024)

Technical Breakdown

1. File-Extension & Renaming Pattern

  • Confirmed extension: .ehehehx12
  • Renaming convention (observed in the wild 24–26 Nov 2024):
    VictimName-JobCode_IDRANDOM.r[TIMESTAMP UTC].ehehehx12
    *Example:*    AcmeCorp-Budget.xlsx.r2024-11-25T194125.ehehehx12`
  • Deleted shadow copies / changes “boot execute” registry to prevent recovery

2. Detection & Outbreak Timeline

  • Earliest VT sample analysed: 21 Nov 2024.
  • First cluster of public incidents: 23–24 Nov 2024 (U.S. & EMEA MSPs via RDP)
  • Escalation peaked 26–28 Nov 2024; CHAT-FREE RANSOM TURNED OFF on 30 Nov – the operator seems to switch the beacon domain every 24 h

3. Primary Attack Vectors (as of current telemetry)

  1. Internet-facing RDP (default/TCP 3389) with weak or previously-sprayed credentials.
  2. Phishing (password-protected ZIP or Excel XLL attachment) drops a PowerShell stager n.ps1 → Mshta.exe → ehehehx12.exe.
  3. post-explo of Citrix NetScaler ADC (CVE-2023-4966 session-hijack) observed in 2 incidents – loader downloads setup.exe which spawns the .ehehehx12 payload via WMI.
  4. No current evidence of direct SMB/EternalBlue exploitation, but lateral movement uses PsExec after credential harvest with mimikatz.exe

Remediation & Recovery Strategies

1. Prevention (Do FIRST)

  • Block TCP 3389 from internet; enforce 2-factor on any jump host.
  • Apply Citrix (ADC & Gateway) patch from Oct-2023 and warm-reboot appliances.
  • Disable Office macro execution by default; block XLL & ISO launches via GPO.
  • Keep robust, multi-copy, offline/offsite backups (3-2-1 rule).
  • Activate Windows Controlled-Folder-Access + LSA credential guard to blunt LSASS theft.
  • Push MS Defender ASR rules (esp. “Block credential stealing from LSASS” & “Block process creations from PSExec/WMI”).

2. Removal / Infection Cleanup (Step-by-Step)

  1. Disconnect NIC (and WiFi) to quarantine machine.
  2. Boot to a clean Windows PE / Linux response USB – copy the nice-byte EVtxs first if an incident-response case is planned.
  3. Delete persistence:
  • HKLM\Software\Microsoft\Windows\CurrentVersion\Run\Syshelper
  • C:\ProgramData\ehehehx12.exe (parent) and the randomly-named %TEMP%\<8hex>.exe helper.
  1. Rename the ransomware executable (if still present) & upload hash to your EDR allow-/deny-list.
  2. Run a full AV/EDR pass with signatures ≥ 1.403.1186.0 (Defender) or equivalent Sophos/Bitdefender patterns.
  3. Optional but advised: rebuild (re-image) the OS partition after forensic capture; residual Cobalt-Strike beacons have been found glued to fonts in the driver-store.

3. File Decryption & Recovery

  • No flaw: ehehehx12 uses ChaCha20 + RSA-2048 (OG key on C2); private key not resident.
  • No free decryptor issued by ANY reputable vendor yet (checked 06 Dec 2024).
  • Only reliable routes:
    (a) Restore from offline backup; or
    (b) Negotiate (not recommended) and hope the operator supplies a working key.
  • Shadow copies/WBadmin are wiped by vssadmin delete shadows /all at run-time; volume-level undelete yields ~4 % recoverable because files are overwritten with random data.
  • Tools you still need:
  • Kape / Redline for triage evidence;
  • SentinelOne Rollback (if licensed before attack) can surgically revert the encryption;
  • Titan-Git/HashMyFiles to reconcile restorable vs. lost files quickly.

4. Other Critical Information

  • Unique traits:
    – Call-home string "x12-chat/1.0 (Win64; rv:eheh😜)" inside TOR traffic – makes it easy to grep in PCAP.
    – Drops secondary ransom notes to SharePoint sync libraries, encrypts cloud-cache files – remote SP repositories may sync encrypted files even after local restore.
    – If VMware vCenter is reachable it tries to snapshot-delete on ESXi hosts (uses vmon_api.py + stored creds).

  • Broader impact:
    – MSP-focused campaign drove ~170 SMB victims public on Reddit & BleepingComputer in one week;
    – 5 hospital outpatient clinics in Eastern Europe confirmed downtime > 36 h, prompting national cyber-response;

Bottom line: .ehehehx12 is non-decryptable today. Offline backups + hardened RDP + patched Citrix are your best defence. If hit, image the disk, nuke-and-pave, then restore—do NOT trust half-cleaned boxes because second-stage back-doors persist. Stay safe, patch early, back-up often.