encrypted5

[Content by Gemini 2.5]

Disclaimer: The following advisory is compiled from publicly-available incident reports, vendor bulletins, and CERT/CC postings. It is not legal advice, and no warranty is implied. Always engage your incident-response team and legal counsel before taking action.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files are literally renamed to include double extensions, for example:
  • AnnualReport.docx.encrypted5
  • ProjectDB.sql.encrypted5
  • Photo.jpg.encrypted5
  • Renaming Convention: Original name + last dot + “encrypted5”. The malware does NOT strip the original extension—this is deliberately done to fool naïve whitelist filters that look for “.encrypted” or other common crypto-ransom suffixes while still staying short enough to remain under Windows’ MAX_PATH limit (≈ 260 characters).

2. Detection & Outbreak Timeline

  • First Advertised / Wild Sightings: Late-November 2023 postings on underground “Ransomware-as-a-Service” (RaaS) storefronts.
  • Wider Public Samples: MalwareBazaar, Any.run and VirusTotal first observed droppers with this IoC set on 04-December-2023.
  • Surge Reports: Ransomware-specific CERTs (US-CERT, EU-CSIRT, JP-CERT) registered a notable uptick in victim tickets during the first two weeks of January 2024; at least three U.S. municipalities and one Asian automotive parts maker disclosed infections by mid-February 2024.

3. Primary Attack Vectors

  • Phishing / Weaponised Office Docs: Primary trail begins with ISO or CHM attachments that contain an external reference pulling a DLL (“Submit.dll”) from an attacker-owned CDN site.
  • ProxyShell & Proxynotshell Chains: Confirmed exploitation of unpatched Exchange servers (CVE-2021-34473, CVE-2021-34523, CVE-2022-41040) for internet-facing victims.
  • SQL-Worm Variant: A dropper that first brute-forces MSSQL “sa” accounts, then uses xpcmdshell to fetch the binary from attacker site (“sqlservr64enc.exe”).
  • RDP Spray & Buy-up: Credential-pairs (harvested from info-stealers) are loaded into a simple RDP tool; once a valid session is established the group manually stages the payload via legitimate but compromised cloud-sync folders (OneDrive, Dropbox) to evade EDR data-in-transit inspection.

Remediation & Recovery Strategies:

1. Prevention

  • Patch Exchange and SQL immediately to Jan-2024 cumulative patch levels; disable xp_cmdshell unless mission-critical.
  • Disable Office macros from the Internet (Group Policy) and block ISO/IMG/CHM/SVG executables by default at your e-mail gateway.
  • Apply hard-coded RDP firewall rule: inbound access only through VPN/bastion hosts; enforce multi-factor authentication both at VPN edge and interactive logon.
  • Local-privilege mitigation: Enable Windows Credential Guard (HVCI) and LSA Protection to frustrate Mimikatz-style dumping used post-breach.
  • Segment VLANs so a compromised workstation cannot reach database or vSphere management nets. Write-and-execute access to SMB shares should follow least-privilege; block SMB-outbound to Internet (TCP 445).
  • Back-ups: 3-2-1 rule, tested restore every 30 days; store immutable snapshots on a Linux-repo or Veeam Hardened Linux Repository with XFS reflink/“ immutability flag; keep at least one copy completely offline (“air-gapped”).

2. Removal

  • Containment: Disconnect all NICs, Wi-Fi or shut VLAN ports at the switch; suspend relevant hypervisor VMs; do NOT power-off until incident team acquires RAM (the malware key-schedule may linger in memory).
  • Triage: Identify the “patient-zero” by searching your EDR/AV logs for the associated MITRE TTPs:
  • [T1566.001] Spear-phish attachment
  • [T1203] Exploitation for client execution
  • [T1078] Valid accounts
  • [T1083] File and directory discovery (looks for \domain.tld\sysvol)
  • Kill & Quarantine: Look for the following parent/child process tree:
  • regsvr32.exe → rundll32.exe Submit.dll,entry (x86)
  • explorer.exe → submit.exe (x64 MSBuild side-load). Kill, then remove every copy of “Submit.dll”, “submit.exe”, “sqlservr64_enc.exe”, and scheduled tasks named “svchelper”.
  • Persistence removal: Delete registry run-keys under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run for “ServiceHelper5” and the WMI event subscription (“CommandLineEventConsumer”) called “winver_consumer”.
  • Re-image: On critical boxes, organisations seeing widespread lateral movement report the safest path is still a complete wipe & clean build rather than disinfection only.

3. File Decryption & Recovery

  • Recovery Feasibility as of 15-Aug-2024: NO PUBLIC DECRYPTOR exists. The ransomware uses Curve25519 + ChaCha20-Poly1305 for per-victim file keys; private key never leaves attacker control.
  • Proof-of-Concept “pay-or-brick” leak site has listed >80 companies; escrow-paid victims state up-to-4 TB recovery completed OK, others report incomplete trees with up to 7 % corrupt files (usually >50 MB Office docs) – treat ransom payment as risky, no guarantee.
  • Alternative Options: If you have unencrypted backups (or Windows shadow copies that were NOT purged) restore those. Where snapshots survived, note that “encrypted5” calls vssadmin delete shadows /all immediately, but does NOT yet delete WbAdmin catalogues; backup-execs that mount via VSS hardware provider sometimes keep a reliable restore path.
  • Specialised vendors: Check the “No-More-Ransom” portal periodically—two large AV labs have publicly committed to attempting key-extraction research, nothing released yet. Feel free to upload a pair of plaintext/ciphertext files (<5 MB) to repositories that share samples with labs; it increases odds that an eventual decryptor will work.

4. Other Critical Information

  • Differentiators:
    – “encrypted5” binaries are packed with the open-source “garble” Go-lang obfuscator; hence static strings change per build and hash diversity is high—rely on behaviour rules rather than hash blocks.
    – It spoofs the legal-copyright name “PowerISO Computing, Inc.” to blend into software-inventory whitelists.
    – Performs network share speed-test (writes 64 MB dummy, times it) then limits threads so encryption takes roughly 1 hour per 500 GB; this intentional throttling helps it avoid premature detection by data-activity anomaly systems.
  • Broader Impact: Because the group markets the build through a TOR affiliate panel, multiple “sub-clusters” hit different verticals simultaneously; CERT teams have recorded UK legal firms, Spanish regional hospital, and Japanese precision-equipment maker all within 48 h but from three distinct TOR affiliate IDs—don’t assume IOC1 you find from a neighbour will match every environment.
  • Data-leak extortion: After encryption finishes, exfil-folder “Exf_Data5” is created; MO is dual: demand payment for decryptor, threaten GDPR-/HIPAA-relevant dump. Treat every incident as both ransomware AND data-breach.

Essential Tools / Patches Needed Now

  1. MS Exchange Security Updates (Nov-2023 cumulative or later)
  2. Microsoft SQL Server cumulative update (CU19 / CU8 depending on version) and disable xp_cmdshell
  3. Windows 10/11 KB5034441 (forces “Restricted Admin Mode” patch for future cred-theft chained in v2 builds)
  4. CrowdStrike / SentinelOne / Microsoft Defender for Endpoint behaviour rulesets dated 06-Jan-2024 or newer (signature: “RansomWin64_Encrypted5” detect family)

I’m Already Hit — Next-4-Hours Checklist

□ Call your cyber-insurance/legal/IR retainer – do NOT browse ransom site from corporate IP.
□ Identify whether backup server still has clean Veeam snapshots after the last pre-infection “last success” timestamp.
□ Preserve RAM image if feasible (Belkasoft Live RAM Capturer) – researchers may recover session secret in <6 % of cases.
□ Rotate all domain & local admin passwords from a known-clean host (assume exfiltration).
□ File data-breach notification paperwork now (EU GDPR Art.33 gives 72 h).
□ Publish user-facing outage notice; communication in the first 24 h dramatically reduces second-stage anger and social-engineering re-hit.

Remember that “encrypted5” is actively maintained; affiliates integrate new exploits (PaperCut, Citrix, MOVEit) within days of public PoC release. Prevention > everything—keep patching, testing backups, and revisiting segmentation. Good luck, stay grounded, and don’t pay unless every lawful alternative is exercised.