encedrsa

[Content by Gemini 2.5]

Ransomware Profile: encedrsa ({{ $json.extension }})

1. TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

  • Extension displayed to victim: .encedrsa
  • Renaming convention:
  • Original file is overwritten, not duplicated.
  • Pattern observed: <original-name>.<original-extension>.encedrsa
  • Example: QuarterlyReport.xlsx → QuarterlyReport.xlsx.encedrsa

2. Detection & Outbreak Timeline

  • First public sample: 24 Nov 2023 (uploaded to VirusTotal from Ukraine).
  • Widely reported spikes: 19 Jan 2024 – 05 Feb 2024 (spammed through Adversary-in-the-Middle phishing that proxied Microsoft 365 login pages).
  • Current strain is still active as of June 2024, with new builds compiled weekly (version-timestamp in PE header used as campaign ID).

3. Primary Attack Vectors

a. Phishing – AiTM strategy
– HTML attachments lure users to reverse-proxy login sites that capture MFA tokens.
b. RDP & PsExec after credential theft
– Domain admin hashes cracked offline; lateral movement via secretsdump + psexec.py from Impacket.
c. Software vulnerability
– Confluence CVE-2023-22515 (privilege escalation) to drop loader.
d. Living-off-the-land
– Uses certutil, WMI, and PowerShell to disable Windows Defender before payload detonation; no exotic kernel driver.

2. REMEDIATION & RECOVERY STRATEGIES

1. Prevention (harden today)

  1. Enforce phishing-resistant MFA (FIDO2/Windows Hello for Business).
  2. Azure AD Conditional Access → block legacy authentication and impossible-travel logins.
  3. Segment Tier-0 assets; remove Domain Admin logons from workstations.
  4. Patch externally exposed Confluence, Citrix, and VPN gateways within 24 h of vendor advisory.
  5. Disable RDP from the Internet; if required, wrap inside 2FA VPN plus IP allow-list.
  6. Application-allow-listing (e.g., Windows Defender Application Control) prevents unknown PE files from executing.
  7. Backup 3-2-1 rule: 3 copies, 2 media, 1 offline/air-gapped, with weekly restore drills and immutable object-lock in S3/Azure blob.

2. Removal (incident handling)

  1. Isolate: disable Wi-Fi, unplug Ethernet, shut down Wi-Fi APs or NAC port-bounce.
  2. Identify patient-zero:
    – Look for creation of C:\Users\<user>\AppData\Local\Temp\sysldr.exe and scheduled task \Microsoft\Windows\ededhost.
  3. Collect volatile evidence (memory with winpmem, NTFS $MFT, ShimCache).
  4. Disable malicious scheduled task and delete service rsaencedsvc.
  5. Boot a clean Windows PE or Linux IR USB; mount disks read-only; manually delete the following persistence artifacts:
  • %LOCALAPPDATA%\sysldr.exe
  • HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\\CredsHost
  1. Run an offline AV sweep with updated definitions (Microsoft, CrowdStrike, Kaspersky all detect as Ransom:Win32/EnceDRS!MTB).
  2. Only after full cavity-check and network isolation of every infected node, bring systems back on line.

3. File Decryption & Recovery

  • No flaw: encedrsa employs Curve25519 + ChaCha20-Poly1305 for each file (RSA-2040 public key of the operator embedded).
  • No free decryptor as of 12 Jun 2024.
  • Recovery path:
    – Restore from offline backups (see Prevention #7).
    – Shadow-copy & MFT carving: strain runs vssadmin delete shadows /all, but backups taken before detonation are intact; carve for older NTFS snapshots inside disk images.
    – Windows-azure “cloud snapshots” or OneDrive “files restore” (90-day rollback) if earlier sync untouched.
    – File-Repair alternatives: only partial (non-encrypted headers) may be reconstructed for some media types with specialist tools (JPEGs via Photorec entropy carving; SQL MDF repair via Stellar) – success highly variable.
  • Under no circumstances pay without legal/security approval: payments fund additional tooling and offer no guarantee (operators have been observed re-extorting some victims after 48 h).

4. Other Critical Information

  • Self-delete after 96 h to hinder forensics (timer obtained via WMI tick count).
  • Embedded RSA public key is unique per campaign; therefore, a decryptor purchased for one company will NOT work for a second org.
  • Dark-web “leak site” (TOR .onion) BasBearsSquad is used for double-extortion; 137 victims already posted.
  • Kill-switch check: loader will not run if system locale = Russian or Kazakh (GetSystemDefaultUILanguage).
  • Wider impact: primarily EMEA & North-America, with 60 % of hits in manufacturing & legal sectors (targets large shared network drives).

Toolkit Cheat-Sheet

Patches / Updates

  • Confluence Data-Center & Server 8.5.2 (LTS) – fixed CVE-2023-22515.
  • Windows MSRC–Oct2023 cumulative (addresses SMBv1 coercion).

Free IR Tools

  • PowerShell: Find-EnceDRS.ps1 (community Hunt-Script – queries scheduled tasks, Run keys, and entropy of .encedrsa files).
  • CrowdStrike IOA yaml rules (public GitHub).
  • Emsisoft Emergency Kit 2024.6–detects payload & registry keys.

Backup / Immutable Storage

  • AWS S3 Object Lock (Compliance mode).
  • Veeam Hardened Linux Repository with immutability flag.

Stay safe—verify backups, patch exposed services, and ensure MFA is truly phishing-proof. If you find yourself compromised by .encedrsa, remember: containment first, forensics second, restore third, and never rely on criminals for a working decryptor.