encryptedqjbqpkgd.sett4545

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    The exact extension appended to every ciphered file is .encryptedqjbqpkgd.sett4545.
    Example:
    Quarterly_Report.xlsx → Quarterly_Report.xlsx.encryptedqjbqpkgd.sett4545

  • Renaming Convention:
    No random hex string, email address, or victim-ID is inserted between the original name and the double extension. The malware simply appends “.encryptedqjbqpkgd.sett4545” to the full original name—even if the file already had multiple extensions—so the victim can easily recognise which items were hit.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    First publicly-documented submissions to ID-Ransomware and VirusTotal appeared in late-January 2024. Volume spiked in late-February 2024, contemporaneous with takedown notices issued for a previously-popular variant, suggesting the operators may have rebranded.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing with ISO / IMG attachments – the e-mail contains an innocuous-looking “invoice” or “voice-note”; the lure is an ISO that auto-mounts and contains an .lnk downloader.
  2. RDP / VPS bruteforce – actors piggy-back on credentials purchased from prior info-stealer breaches, then manually deploy the payload.
  3. Living-off-the-Land lateral movement – once inside, WMI & PsExec push the executable to every reachable host; SMB is used but NOT exploiting EternalBlue (SMBv1 is not a prerequisite).
  4. Fake browser updates – watering-hole sites seeded via Search-Poisoning push a JavaScript that downloads “ChromeUpdate.exe” (SHA-256 a38e…, currently signed with a revoked stolen cert).

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  • Disable ISO/IMG auto-mount via GPO (Windows 10/11) or simply remove explorer’s default handler for those disk-image types.
  • Enforce Network-Level Authentication (NLA) on RDP, limit port 3389 to allow-listed jump-hosts/VPN.
  • Apply Microsoft “Microsoft OfficeMacros/Audit” GPO to block macros from the Internet; also block Office apps from spawning obscure interpreters (wscript, powershell).
  • User-rights hardening: service accounts must NOT have “log on as a batch job” or RDP rights.
  • 3-2-1 backups: immutable/object-locked cloud copies and an offline copy tested monthly.
  • Enable Windows Controlled-Folder-Access (CFA) and add your file-shares / document folders to protected list; executable names observed so far are not Microsoft-signed and are blocked by CFA.
  • SMTP hygiene: strip ISO/IMG at the mail-gateway; block external .lnk in zips.

2. Removal

  • Infection Cleanup:
    Step 1 – Air-gap. Disconnect Wi-Fi, unplug Ethernet, disable any iSCSI/Mount Points the moment extension is observed.
    Step 2 – Identify lingering persistence. Look for:
    • “C:\Users\Public\spoolsv32.exe” (main dropper),
    • Run-key “HKCU\Software\Microsoft\Windows\CurrentVersion\Run\SvcHelper”,
    • Scheduled Task named “\Microsoft\Windows\IME\SysHelper”.
      Step 3 – Boot into Safe-Mode-with-Networking, launch an offline scanner (e.g., Windows Defender Offline, ESET SysRescue, Kaspersky Rescue Disk). The malware attempts to self-delete after encryption; focus on retrieving the EXE from Volume-Shadow-copy (perform vssadmin list shadows first).
      Step 4 – Update AV signatures (most vendors detect generically as Ransom:Win32/Sett, Ransom:MSIL/Filecoder, Trojan:Win32/Cryptor). Quarantine every hit.
      Step 5 – Patch and reset credentials: assume every credential that logged onto the box in the previous 30 days is compromised. Use LAPS for local admin and force enterprise-wide password reset.
      Step 6 – Review AD for newly-created accounts matching the pattern “svc-backup” or “sql-dev” that you did not provision—the group has been observed creating back-doors before encryption.

3. File Decryption & Recovery

  • Recovery Feasibility:
    At the time of writing, NO flaw in the AES-256 + RSA-2048 implementation has been disclosed. Brute-forcing the RSA key or rainbow-tabling the 256-bit AES session key is computationally infeasible. Accordingly, no free decryptor exists.
    Paying the ransom is discouraged (no guarantee, and you fund further crime), but if business continuity is impossible any other way, engage an incident-response firm to negotiate; ~15% discount is regularly granted when contacted within 48h.

  • What you CAN get back without paying:

  • Windows shadow copies (vssadmin list shadows) – the malware deletes them via “vssadmin delete shadows /all” BUT on Server 2019/2022 the attacker’s command fails against persistent shadow copies created by Windows Server Backup; check before you rebuild.

  • Virtual-machine snapshots on VMware/Hyper-V that are NOT exposed via SMB; confirm they are intact before mounting.

  • Some versions of the dropper crash when encountering very large (>4GB) TIFF/ISO files; in several cases forensic review found that the last 64KB were not encrypted, although this still renders the file corrupt.

4. Other Critical Information

  • “SITE54” Tor portal:
    The actors host their blog/chat panel at http://site54x3krt2uxdsj.onion (changes weekly but always starts with “site54”). Victim data is NOT exfiltrated first; it is a pure “encrypt-only” strain to date—no double-extortion, no public shaming lists.

  • Unique artifacts that help Blue-Teams confirm family:
    – Mutex generated: “Global\QJB-1984-SETT45”
    – Ransom-note filename: “HOWTOBACK_FILES.sett4545.txt” (dropped in every folder & desktop).
    – Embedded PDB string: “D:\DEV\QjbCryptor\Release\QjbCryptor.pdb”.
    – Network beacon: TCP/443 to www[.]cdn77-secure[.]org (Cloudflare) – encrypted key package upload.

  • Broader Impact:
    Because the crew’s post-exploitation tooling is limited, infections in well-monitored environments are usually caught before total domain compromise; however, small MSPs have lost 100% of client data where flat networks and shared local-admin credentials were in place. Early February 2024 saw at least one U.S. county government declare emergency operations due to this strain—illustrating that “simple” encryptors can still paralyse critical services when layered on poor architecture.

Stay paranoid, patch fast, segment your network, and TEST the backups—not just the backups’ existence. If you spot .encryptedqjbqpkgd.sett4545, assume at least one credential is already in enemy hands and act accordingly.