eris!

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .eris! (note the exclamation mark).
  • Renaming Convention:
    – Original filename → <original_name>.eris!
    – Example: Contract.docx becomes Contract.docx.eris!
    – No e-mail, random string, or victim-ID is inserted—just the single suffix.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    – First submitted to ID-Ransomware and uploaded to VirusTotal on 1 May 2019.
    – Active campaigns peaked between May–July 2019, with sporadic re-appearances through Q4 2019.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. RDP brute-force / credential stuffing → manual drop of startup.exe (Eris loader).
  2. Exploitation of un-patched SMB (EternalBlue – MS17-010) when attackers pivot laterally inside a network.
  3. Malspam attachments (ISO or ZIP containing a JS/VBS downloader that pulls the final payload).
  4. Pirated software bundles (“cracks”, keygens) that side-load the Eris loader.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    – Disable SMBv1 via Group Policy or PowerShell: Disable-WindowsOptionalFeature –Online -FeatureName SMB1Protocol
    – Patch Windows systems with MS17-010 (and every current cumulative update).
    – Rate-limit & audit RDP: enforce NLA, 2FA, strong passwords, whitelisted IPs, and “Account lockout” policy.
    – Segment networks; block TCP 135,139,445,3389 at perimeter for non-essential hosts.
    – Application whitelisting (WDAC/AppLocker) to stop unsigned %TEMP%\*.exe launch.
    – Maintain offline (immutable) backups—3-2-1 rule—verified nightly.

2. Removal

  • Infection Cleanup (step-by-step):
  1. Physically isolate the affected machine(s) or disable Wi-Fi / LAN.
  2. Collect volatile artefacts (memory dump) if forensic investigation is required.
  3. Boot from a clean Windows PE / Linux recovery USB or mount the drive on a known-clean workstation.
  4. Manually delete these artefacts (typical paths):
    C:\Users\<user>\AppData\Local\Temp\startup.exe
    C:\ProgramData\oracle.dll (Eris DLL injected into svchost)
    Registry HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Oracle
  5. Run a reputable AV/EDR engine with up-to-date signatures (Windows Defender, Sophos, Kaspersky, ESET, etc.) to quarantine residual components such as svchost.exe copies or random-named payloads.
  6. Install outstanding OS & software updates before returning the machine to the LAN.
  7. Change all local admin and domain passwords from a clean workstation.

3. File Decryption & Recovery

  • Recovery Feasibility:
    – Files encrypted by .eris! are secured with Salsa20 (key) + RSA-1024 (session key wrapped with attacker’s public key).
    – Private RSA key never leaves the C2 → NO free decryptor available.
    – Option A: Restore from offline backups (strongly preferred).
    – Option B: Attempt to rebuild from unaffected shadow copies (vssadmin list shadows) BEFORE running the removal steps—Eris usually deletes them (vssadmin delete shadows /all) but sometimes misses USB-attached volumes.
    – Option C: Negotiation with criminals is not recommended (they demand 0.15 BTC; payment does not guarantee delivery of a working key, and it fuels further crime).
  • Essential Tools:
    – MS17-010 SMB patch: https://docs.microsoft.com/en-us/security-updates/SecurityBulletins/2017/ms17-010
    – Kaspersky Virus Removal Tool / ESET Online Scanner / Malwarebytes for clean-up.
    – PC Hunter / Autoruns to flush malicious services & automatic run keys.

4. Other Critical Information

  • Unique Characteristics:
    – Eris can operate off-line: once launched it encrypts with the embedded public key even if the host is immediately disconnected.
    – Drops ransom note @[email protected] in every folder and on the desktop; no TOR site—victims are told to e-mail <[email protected]> with a hard-coded victim-ID (8 random hex chars).
    – Terminates >160 processes (SQL, Exchange, Outlook, MySQL, Steam, etc.) to unlock files before encryption.
    – Self-deletes after encryption; no lateral-spread worm component, but attackers use PsExec/Mimikatz for manual lateral movement.
  • Broader Impact:
    – Victims are mostly SMBs running outdated Win7/2008R2 or poorly secured RDP.
    – Eris acted as a “bridge” family—early samples were sold on underground forums, later merged into the “MatchaNews” RaaS (Sept 2019).

Bottom line: .eris! cannot be decrypted without the criminal’s private RSA key. The only reliable path back to production is clean, offline backups plus diligent patching and hardening. Adopt the controls above now and you will block not only Eris but the majority of commodity ransomware that relies on the same vectors.