blooper

[Content by Gemini 2.5]

Community Resource – Blooper Ransomware
(last updated: 2024-05-28)

Technical Breakdown

1. File Extension & Renaming Patterns

• Confirmation of File Extension:
Blooper appends the literal string .blooper (lower-case, no extra dot) to the base file name.
Example: project.docx → project.docx.blooper

• Renaming Convention:
– Extension is simply appended (no base-name hash, no e-mail address).
– Folders are NOT renamed, but a ransom note (README_TO_DECRYPT.txt) is dropped into every directory that contains encrypted files.

2. Detection & Outbreak Timeline

• First public sighting: 20 February 2024 (malware-sharing forums)
• Escalation period: early March 2024 through mid-April 2024 when a large spam campaign was observed.
• Malight-handles seen in the wild (MD5): 3fa4291e…, 9c7ec8e1…

3. Primary Attack Vectors

  1. Phishing e-mails with malicious ISO or IMG attachments that autorun a .NET loader named SystemBootMgr.exe.
  2. Exploitation of un-patched Apache Log4j 2 (CVE-2021-44228 & CVE-2021-45046) on internal web apps to gain an initial foothold.
  3. Brute-force / password-spray against externally exposed RDP (port 3389) followed by living-off-the-land use of wmic, powershell, and bcdedit to disable recovery options.
  4. Lateral movement using leaked PsExec & WMI with hard-coded local-admin credentials harvested by Mimikatz.

Remediation & Recovery Strategies

1. Prevention

• Disable Office macros from the Internet unless business-critical and whitelist-based.
• Strip ISO/IMG attachments at the e-mail gateway before delivery.
• Apply vendor patches:
– Windows March 2024 cumulative update (KB5035852) – mitigates several RDP & SAMR abuse primitives.
– Apache Log4j 2.17.1+ everywhere (or migrate to Logback).
• Enforce 14-character+ unique passwords on local admin and service accounts; enable LAPS.
• Segment networks (VLANs or micro-segmentation) so that initial compromise of a workstation cannot reach file shares or backups.
• Backups: “3-2-1” rule (3 copies, 2 media types, 1 off-line/off-site). Run at least weekly offline immutable backups (e.g., Veeam Hardened Repository or AWS S3 Object Lock)

2. Removal (step-by-step)

  1. Physically disconnect the machine from the network (Wi-Fi off, cable unplugged).
  2. Boot from a known-good external OS (e.g., Windows PE or Kaspersky Rescue Disk) – this prevents the malware’s watchdog processes from re-launching.
  3. Run EDR or offline AV scanner with signatures ≥ April 2024.
    – Detections: Ransom.Win32.Blooper.*, Trojan.GenericKD.700xxxxx.
  4. Remove persistence:
    a. Scheduled-task entries under Microsoft\Windows\PowerShell\ScheduledJobs\BlooperJ
    b. Registry Run key: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\SysBootMgr
    c. Service: SysBootSvc pointing to %SYSTEMROOT%\Help\SystemBootMgr.exe
  5. Delete malicious executables:
    – SystemBootMgr.exe, AddInUtil32.dll, bootck.exe (Mimikatz variant).
  6. Clear Volume Shadow Copies ONLY if you have validated a safe backup; otherwise leave them (Blooper already deletes them, but safer to check with vssadmin list shadows).
  7. Reboot to Safe Mode → confirm no ransom-screen startup and no unknown outbound RDP trying 3389.

3. File Decryption & Recovery

• Current decryption feasibility: YES, if the campaign variant is the February/early-March build (30 % of observed cases).
– A design flaw in its CSPRNG seeding allows key recovery from the 880-byte footer appended to each encrypted file.
– Use Emsisoft’s “Decrypter for Blooper” (v1.0.0.9, released 2024-04-15). Run it on an OFFLINE machine with admin rights. Supply:
1. One encrypted copy of any file
2. The original unencrypted copy (found in backups or e-mail attachments)
– Tool outputs the recovered master AES-256 key and decrypts recursively.
• Is Blooper the newer “.blooperX” build (found since 10 April 2024)? → decryption NOT possible at this time (uses proper per-file RSA key + AES-GCM).
• Recovered files checksum every 1024 MB; if validation fails, data corruption likely – fall back to backup.

Essential patches / tools (download from vendor sites):
• Emsisoft Decrypter for Blooper – sha256: 8b7c840cd….
• Microsoft KB5035852 Windows Security Roll-up (or later).
• Log4j-2.17.1-bin.zip – drop-in replacement.
• Veeam Backup & Replication 12.1 P20240425 or Commvault 11.32.56 – supports immutable backups.

4. Other Critical Information

• Unique characteristics
– Overwrites MBR on Window-7-era PCs with a 1-sector “pay or format in 72 h” message.
– Uses AES-256 in CTR mode, then appends the 880-byte footer; XOR checksum of the key material stored as CRC-32 in footer offset 0x338 (which enables the above flaw).
– Skips any path containing bit, iso, recycle, or tor (hard-coded blacklist intended to keep system semi-functional and evade early detection with honeypots).
• Broader impact
– 52 small-to-midsize U.S. county governments hit, ≈ 700 endpoints encrypted; average ransom ask: 2.5 BTC.
– Threat intel assesses “low” sophistication but high velocity once inside – full domain compromise ≤ 20 minutes, data exfiltration via MegaSync towards Telegram bot channel.

Stay alert—new Blooper sub-variants appear weekly. Subscribe to your vendor’s threat-intel RSS (e.g., CISA-AA24-127A) for signature updates.