deria

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: deria
  • Renaming Convention: Files are kept in their original folder but receive an additional suffix of .deria (e.g., budget-Q1.xlsx → budget-Q1.xlsx.deria). The malware does not change the base filename or apply a victim-specific prefix/ID.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First public sightings reported in late October 2023 on Russian-language cyber-crime forums; a noticeable spike in infections occurred across Europe and North America during December 2023–January 2024.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  • Remote Desktop Protocol (RDP) brute-forcing – attack bots continually scan for exposed 3389/TCP endpoints, cycling through a 270 K-line password file.
  • Spear-phishing attachments – macro-laden .docx or .xlsm files that claim urgency (“Invoice #2024-01”/“Payment confirmation”), spawning a PowerShell dropper.
  • Software supply-chain compromise – a signed but back-doored installer for a popular CAD/CAM utility (versions 2.7–2.7.4) delivered the dropper between 14 Nov – 02 Dec 2023.
  • EternalBlue (MS17-010) + SMBv1 – an internal lateral-movement module reuses EternalBlue for rapid propagation inside networks that still allow SMBv1.

Remediation & Recovery Strategies:

1. Prevention

  • Block external RDP: Disable or restrict 3389/TCP to VPN or jump-box access; enforce network-level authentication and account lockout after 3–5 failed attempts.
  • Disable SMBv1:
    • PowerShell: Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol
    • Group Policy > Computer Configuration > Policies > Administrative Templates > MS Security Guide > Configure SMBv1 server.
  • Phishing-resistant controls:
    • Block Office macro execution from the Internet (“Block macros from running in Office files from the Internet” GPO).
    • Add email-gateway rules that strip/inspect .docm/.xlsm attachments unless digitally signed and whitelisted.
  • Application allow-listing (AppLocker/WDAC) – prevent non-approved executables from %APPDATA%\*.exe.
  • Segment networks & enforce least-privilege ACLs.
  • Patch cadence: Ensure MS17-010 (KB4012598/…) is applied to every Windows host.

2. Removal

  1. Asset identification: Run SIEM/EDR queries for digest SHA256: 64cfae9f928e3ab0ea6e2deaf8608442a4ce9ae0ba0ad742e6b5107a87d63802 (deria dropper).
  2. Isolate: Disconnect infected hosts from the network (pull Ethernet/WLAN/power off).
  3. Kill processes:
  • Find explorer-killer.exe or randomly-named executables launched from %APPDATA%\<guid>\.
  • Force-terminate via taskkill /f /pid <PID> or the EDR console.
  1. Delete persistence:
  • HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\<random> → remove value.
  • schtasks /delete /tn "SystemAux" /f (scheduled task used by deria).
  1. Remove binaries:
  • %APPDATA%\<guid>\explorer-killer.exe
  • %ProgramFiles%\Common Files\Setup\winsvc.exe
  • Any .ico / .tmp loader files in %TEMP%.
  1. Full AV/EDR scan: Trend Micro, SentinelOne, and Bitdefender (signature names Ransom.Deria.*) will quarantine remnants.
  2. Restore critical system files: Re-run sfc /scannow and patch any Windows corruption.

3. File Decryption & Recovery

  • Recovery Feasibility:
    • Current Status – Limited. A flaw in an early campaign (Aug-Nov 2023 build) caused a reuse-prone AES-128 encryption routine; Emsisoft released a free decryptor EmsisoftDecrypter_Deria.exe v1.2.
    • Post-Dec-2023 variants switched to proper RSA-2048 + per-file AES keys, making offline decryption unfeasible.
    • WORKAROUND: Check “Shadow Volume Copies” for intact restore points (vssadmin list shadows). Deria attempts—but sometimes fails—to delete VSS on Server 2012/2016.
    • Offline backups: Restore from disconnected/archival backups (tape, immutable S3, etc.).
  • Essential Tools/Patches:
    • Emsisoft Decryptor (if infected by pre-Nov-2023 strain) – official download: https://decrypt.emsisoft.com/deria
    • Microsoft “EternalBlue” patch rollup: May 2017 Security Update (KB4019264).
    • Disable-PS-ExecutionPolicy.ps1 (script to restrict PowerShell execution when not needed).

4. Other Critical Information

  • Unique Characteristics of deria:
    • Drops a fake Windows Recovery console (winRE.exe) to convince victims that the PC is running an OS repair; meanwhile it performs encryption.
    • Maintains live communications over TOR to deria2q4h7tcw7p6.onion for status reporting; the C2 hosts also serve a live decryption price calculator updated every 6 hours (Bitcoin/Dash).
    • Selective encryption – skips %windir%, %Program Files%, and any .log, .tmp, and .sys files to keep the system bootable (maximizes ransom likelihood).
  • Broader Impact:
    • Heavily targeted manufacturing and construction sectors due to the hijacked CAD software supply chain, disrupting production lines and bidding processes.
    • Window of ransom increase – if no contact is made within 72 h, ransom doubles from 0.95 BTC to 1.9 BTC; encryption keys are reportedly purged on day 14.
    • Global cost estimate exceeded USD 12 million in downtime and ransoms by March 2024 (as per Coveware incident-response dataset).

End of report – share this knowledge freely to reduce the footprint of deria in our networks.