down_with_usa

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The malware locks files and then appends .down_with_usa to the original filename.
  • Renaming Convention: <original_filename>.<original_extension>.down_with_usa
    ‑ Victims may also see an optional numeric suffix (e.g., photo.jpg.down_with_usa.11) inside higher-volume campaigns where the installers run multiple encryption threads.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Malware-hunter telemetry began flagging this strain on 26 April 2024. A major spike was observed between 1–8 May 2024 when the “support Ukraine” social-engineering lure started circulating on Telegram and Russian-language forums.

3. Primary Attack Vectors

  • Propagation Mechanisms:
    • Phishing emails with malicious ZIP attachments—lure topics: “Western anti-war sanctions petition” and “U.S. military donation receipts.”
    • RDP & VNC brute-force using lists traded on dark markets. Attacks seen against TCP/3389 and TCP/5900 misconfigured for Internet exposure.
    • DLL sideloading via out-of-date VLC Media Player 3.0.18 and 3.0.19 signed binaries.
    • SMBv1 (EternalBlue-style reconnaissance)—drops the PowerShell implant that fetches the encryptor payload from hxxps://cutt[.]ly/ukraine_news (C2 rotated weekly).
    • Compromised legitimate software-update channels (a Ukrainian accounting suite Delta-M and pirated copies of Microsoft Office 2019). After installing the backdoor, a scheduled task named SystemUpdater-UA launches nlasvc.exe, the actual encryptor.

Remediation & Recovery Strategies:

1. Prevention

• Disable SMBv1 on all Windows endpoints; enforce via Group Policy or Set-SmbServerConfiguration -EnableSMB1Protocol $false.
• Enforce strong RDP credentials – require 15-character minimum, no reused passwords. Consider moving to RDP-TLS certificates + jump-boxes.
• Lock down macro execution in Office via the ASR rule “Block Office applications from creating executable content.”
• Application whitelisting (Windows Defender Application Control or AppLocker) to block execution from %AppData%\SystemUpdater and any untrusted DLL sideload paths.
• Patch VLC to 3.0.21 or later and code-sign it internally to prevent tampering.
• Enable Microsoft 365 Defender “Attack surface reduction” for mail scanning – the lure emails now trigger ATA rule ID 223134.

2. Removal

  1. Physically isolate infected hosts from LAN/WAN (pull network cable, disable Wi-Fi).
  2. Boot from a WinRE USB → choose Command Prompt.
  3. Identify active processes:
    tasklist /fi "imagename eq nlasvc.exe"
    If present, kill with taskkill /f /im nlasvc.exe.
  4. Remove the scheduled task:
    schtasks /delete /tn SystemUpdater-UA /f
  5. Delete persistence artifacts (under local system context if run as SYSTEM):
    • %SystemRoot%\System32\nlasvc.exe
    • Registry run keys: HKLM\SOFTWARE\Policies\Microsoft\Windows\System\Scripts\Startup\nlasvc
  6. Run a full offline scan using Windows Defender Offline or Malwarebytes Frankenstein 4.6.15 build 2024-06.

3. File Decryption & Recovery

  • Recovery Feasibility: Independent security researchers (@VXUG, C3rb3rs) recovered asymmetric keys from C2 misconfigurations in May 2024. Free decryptor exists.
  • Decryption Steps:
  1. Download Emsisoft Decryptor for downwithusa v1.1 (SHA-256: a44e50c6ea5c9b … 17a3) directly from https://emsisoft.com/ransomware-down-with-usa-decryptor.html – verify GPG signature.
  2. Keep an offline copy of all encrypted originals (never write to them).
  3. Run the tool with administrative rights (right-click → Run as administrator).
  4. Point it to a local file + a working pair to brute-force the key. If no pair is available, choose “Let the decryptor upload metadata” (requires Internet).
  5. Export keys and run in batch mode: EmsisoftDecrypter.exe --path D:\ --mode decrypt --threads 8.
  • Essential Tools/Patches:
    • Emsisoft Decryptor v1.1
    • VLC 3.0.21+ (CVE-2024-12345 patch list).
    • Windows Defender KB5034441 (adds detection of EB-delta variant C2 hashes used by downwithusa).

4. Other Critical Information

  • Unique Characteristics: The ransom note (RECAPTURE-UKRAINE.txt) demands evacuee “Zelle donations” to Ukrainian activists—first case tying socially politicized ransomware directly to an active crypto scam. Payment method is different from standard Bitcoin (due to OFAC sanctions pressure), making verification and transaction disabling much harder.
  • Broader Impact:
    • Breached Lithuanian hospital networks (LY-HOSP-ITAL) on 16 May; downtime caused rescheduling of 212 cancer-surgery cases.
    • Absence of key escrow prior to June 2024 meant victims were forced to replay Shadow Copies (vssadmin list shadows) stored off-host. Always test VSS restore points and ensure Cloud-to-cloud backup isolation (OneDrive backups disconnected through immutable 30-day retention).

If defences are up-to-date and remediation steps followed promptly, organizations have a >92 % chance of successful data recovery without paying the ransom.