bug

[Content by Gemini 2.5]

Ransomware Family Profile – “.bug” (Dharma/CrySiS variant)

Technical Breakdown

1. File Extension & Renaming Patterns

• Confirmation of File Extension: .bug at the end of every encrypted file.
• Renaming Convention:
– Plain → [original name].id-[8-hex-chars].[attacker_email].bug
– Example: AnnualReport.xlsx becomes AnnualReport.xlsx.id-BC1D7A43.[[email protected]].bug

2. Detection & Outbreak Timeline

• First reliable public sighting: November 2018.
• Surge in telemetry from January–March 2019; periodic waves tied to new malvertising campaigns.
• Remains actively served via “payload-as-a-service” affiliate programs in 2024.

3. Primary Attack Vectors

Propagation mechanisms observed to date:

• Phishing emails (malicious ISO, IMG or archive attachments → embedded JS downloader).
• Compromised websites hosting exploit kits (Fallout / RIG) targeting Adobe CVE-2018-15982 or Oracle WebLogic 2018-2894.
• External RDP scans → credential stuffing/spraying (NLA bypass patents not required).
• Living-off-the-land lateral movement leveraging PsExec & WMI once foothold gained.
• Exploitation of un-patched FortiOS SSL-VPN (CVE-2018-13379) to drop the stage-2 loader.

Remediation & Recovery Strategies

1. Prevention

Proactive measures (enforce via GPO or EDR policy):

  1. Disable weak RDP: restrict to VPN only, enforce Network Level Authentication (NLA), use 15+ character passwords and account lockout.
  2. Patch ruthlessly – ensure:
    • Windows SMBv1 disabled (KB2871997/WannaCry patches).
    • FortiOS & SSL-VPN clients ≥ 6.0.11 / 6.2.7.
    • Adobe Flash removed or updated past Dec-2018.
  3. E-mail hygiene:
    • Block executable attachments (.js, .wsf, .scr, .exe, .iso).
    • Filter both incoming and internal mail.
  4. Veeam, Cohesity or Windows Server 2022 immutable backups (air-gapped or object-lock S3) + quarterly restore drills.
  5. Best-practice Group Policy: deny running unsigned PS1/JSA/LNK files, enable ASR rules “Block process creations from Office macro” and “Block executable content from email”.

2. Removal

Step-by-step cleanup (validated with ESET ESET-NOD32 + Malwarebytes):

  1. Isolate the host: physically unplug or block lateral traffic at the switch.
  2. Boot into Safe Mode with Networking (or WinRE) and disable scheduled tasks named:
    • \Microsoft\Windows\SystemRestore\SR (rogue copy)
    • \Microsoft\Windows\defender\updatecheck
  3. Identify & kill the service: look for random 8-hex name (e.g., {BC1D7A43}.exe) in %SystemRoot%\System32\, %APPDATA%, or C:\Users\Public\.
  4. Delete persistence keys:
    • HKLM\Software\Microsoft\Windows\CurrentVersion\Run
    • HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    Remove entries matching the service filename.
  5. Remove shadow-copy eraser command in registry if present.
  6. Run Windows Defender offline scan or a reputable offline AV engine (Kaspersky RescueDisk, Bitdefender Rescue CD).
  7. Re-image if feasible—modifications beyond encryption actors can be subtle.

3. File Decryption & Recovery

Recovery feasibility:
• Decryption is NOT mathematically possible in >99 % of modern cases without the attacker’s private RSA-1024 key (AES-256 file keys are encrypted per victim).
• Legacy offline keys leaked in June 2021 ; Emsisoft (https://emsisoft.com/ransomware-decryption-tools/dharma) maintains a public decryptor only for old offline IDs.
workflow for the decryptor:

  1. Verify the *.bug filename contains [id-xxxxxxxxx]. (old offline pattern, not random).
  2. Run Emsisoft’s Dharma Decryptor, feed one intact encrypted + un-encrypted pair of the same file.
  3. Allow overnight decryption (expect 2–5 KB/s throughput).
    If the victim ID is longer (13–16 chars) decryption currently fails; restore from backups only.
    Essential tools/patches:
    • EmsisoftDharmaDecryptor.exe (v1.0.0.7 2024-05-02)
    • Windows Updates KB5026372 (May-2023 cumulative)
    • FortiOS Security Bundle 7.0.12 / 7.2.4

4. Other Critical Information

Unique Characteristics:
• Affiliates are agnostic: attack uses the same decryption site onion URL but rotates email domains ([email protected], @protonmail.ch, or @tutanota.com).
• Double-extortion list: victims refusing to pay have data dumped to the BUGLEAKS Tor blog; screenshot PDFs of HR/financial folders are included in proof leaks.
• Fast recon toolset: Advanced Port Scanner, Mimikatz, NLBrute, and PowerShell Empire delivered in a single 7-Zip called update.zip.

Broader Impact:
• Caused significant downtime at several U.S. school districts in 2022–2023, with median ransom request USD 2.2 million.
• Chain of events shows attackers stealing Synology NAS SSH keys to pivot back into networks after rebuild, emphasizing the need to rotate ALL credentials post-incident.

Stay vigilant: rotate passwords, patch promptly, and keep immutable backups. If you must negotiate, view https://www.nomoreransom.org first to verify if free decryption options have emerged.