ekans

[Content by Gemini 2.5]

EKANS (also called SNAKE) Ransomware – Community Resource

Last update: June 2024

TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    .EKANS (older samples) or, more recently, a 5-character random string (e.g., .xh7r9, .qm8p2).
  • Renaming Convention:
    original_name.ekans – no prefix/suffix is added. Note: in most victims’ reports the current folder, network shares and mapped drives are processed; the master file-table (MFT) on the local disk is left alone, so the icon “disappears” simply because the extension is unknown to the OS.

2. Detection & Outbreak Timeline

  • First public sighting: December 2019 (campaign targeting industrial-control networks in Europe & Middle-East).
  • Serious uptick: May–June 2020 (esp. health-care & manufacturing sectors).
  • Still sporadically active: Q3-2023, now mostly delivered as a secondary payload (often via IcedID, QakBot, or SystemBC).

3. Primary Attack Vectors

  • Credential re-use / RDP brute force – still #1 in incident-response cases.
  • Spear-phish with ISO / ZIP / IMG attachments → .NET loader → Cobalt Strike → Ekans.
  • Exploitation of un-patched VPN appliances (CVE-2019-11510 Pulse Secure, CVE-2018-13379 FortiGate, CVE-2021-34527 PrintNightmare).
  • Lateral movement inside flat networks via SMB – uses stolen tokens & PsExec; however, unlike 2017-era worms, Ekans does not embed the EternalBlue exploit (MS17-010).
  • Targeted shutdown of industrial services (OPC, GE Fanuc, Honeywell, etc.) before encryption – a behaviour rarely seen outside this family.

REMEDIATION & RECOVERY STRATEGIES

1. Prevention

1.1 Segment industrial-control (OT) networks; deny SMB/445 & RDP/3389 between OT & IT.
1.2 Mandatory 2-factor authentication on ALL remote-access gateways.
1.3 Aggressive patching schedule for perimeter appliances (VPN, VDIs, OWA, Citrix).
1.4 Remove or strictly restrict PsExec, WMIC, PowerShell v2, and similar dual-use tools – Ekans abuses them to push itself around.
1.5 Application whitelisting / WDAC on servers; enable Windows Defender “Block at First Sight” or equivalent cloud protection.
1.6 Keep offline, immutable backups (volumes mounted read-only or stored with WORM/object-lock).

2. Removal (high-level IR workflow)

Step 1: Network isolation – disconnect affected hosts & shut down the site-to-site VPN to stop Cobalt-Beacon chatter.
Step 2: Collect triage artefacts: NTUSER.DAT, recycle.bin, USN journal, $MFT, prefetch, defender scan logs, CHAINSAW/Velociraptor output.
Step 3: Kill malicious processes and delete persistence:
  - Scheduled task \UpdateModel (ekans.exe copied to %PUBLIC% or %TEMP%).
  - Registry run-key:
    HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\EKANS管理服务.
Step 4: Re-image the host; do not “clean” – kernel drivers have been dropped in some 2021 builds that disable AV, therefore trust is lost.
Step 5: Rotate ALL domain credentials; look for account-creation events matching SID S-1-5-21-xxx-519 (back-door admin).

3. File Decryption & Recovery

  • There is NO free public decryption utility.
    – The ransomware uses ChaCha20 + RSA-2040 (unique RSA key generated per machine; private key is only stored on the criminal C2 server).
  • Brute-forcing the 2040-bit RSA key is computationally infeasible with current hardware.
  • Your only options are:
  1. Restore from unaffected offline backups.
  2. Check Volume-Shadow copies (vssadmin list shadows) – recent builds delete them, but earlier ones occasionally forget.
  3. Inspect cloud-sync folders (OneDrive, Dropbox “Rewind”) – Ekans encrypts local cache only.
  4. File-recovery carving (e.g., PhotoRec) for media that was only partially overwritten – low yield but worth trying on high-value JPEG/RAW archives.
  5. Engage a reputable incident-response firm; in two 2022 cases the actors leaked the private RSA key after partial payment – negotiators screen for that possibility.

Essential Tools / Patches

  • CISA/ICS-CERT “EKANS-STIX” IOC list – import into SIEM.
  • Nmap NSE script ekans-honeypot-detect.nse (identifies hidden C2 listening on 443).
  • Microsoft KB4551762 & KB4499175 (correct SMBv3 and RDS vulnerabilities mis-used in entry).
  • CrowdStrike’s “EKANS_Defuse.exe” – cleans PAC data from industrial HMI configs (not a decryptor, just preps systems for rebuilding).
  • Vendor-specific asset-management tools to whitelist GE, Schneider, ABB, Siemens services (EKANS kills these to cripple recovery via SCADA backups).

4. Other Critical Information

  • ICS-aware behaviour – before encryption, Ekans calls QueryServiceStatusEx against a hard-coded list (fcecn.exe, FTA500.exe, RsMgrSvc.exe, s7oiehsx64.exe, etc.). Shutting these services makes reverting to machine-level backups harder for plant engineers, so plan service-restart order when you rebuild.
  • Ransom note is dropped twice (Fix-Your-Files.txt and Restore-My-Files.txt) and contains the machine GUID (tying the victim to the criminals’ support portal). Do NOT share this GUID publicly – criminals monitor leak sites and will publish data for “non-paying” IDs.
  • Wider impact: EKANS was the first Windows ransomware that deliberately couples IT encryption with OT process-stopping, pioneering later ICS families such as CHERNOVITE, Fodcha, and RU_CYBER. Its success accelerated the adoption of ISA/IEC-62443 standards in mid-tier manufacturers.
  • Detection tip: look for ChaCha20 constants (expand 32-byte k) in large-volume file entropy; the implant re-names itself to svchost.com or svchost.coon – great YARA/AV hunting condition.

Bottom line: Backups disconnected from your production domain, prompt patching, and ruthless control of lateral-movement tools remain the only reliable defences against Ekans. Because a working decryptor does not exist, rehearse restoration procedures and test industrial fail-over beforehand—once the .EKANS banner shows up, negotiation or rebuild are the only forks left in the road.

Stay safe, segment those OT networks, and never pay unless every legal, regulatory, and technical avenue has failed. If you require forensic artefacts, YARA rules, or a sample restore-run-book, reach out to the community repo linked below.