encrypted*

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: encrypted** (yes — the asterisk is literally written into the new file name, e.g. report.xlsx.encrypted*).
  • Renaming Convention: Appends the extension .encrypted*, preserving the original file name and original extension first (e.g. Budget2024.xlsx.encrypted*). Drives and specific sub-folders are usually left un-renamed.

2. Detection & Outbreak Timeline

  • First victim posts appeared on 2024-04-22 in Reddit & BleepingComputer forums.
  • A steep uptick in submissions to ID-Ransomware was logged 30 Apr–03 May 2024, indicating the start of wider in-the-wild campaigns.

3. Primary Attack Vectors

  • Built-in Itself Parasite (no exploit; no worm). In almost every confirmed incident the compromise began with:
    – exposed, weakly-credentialed RDP or AnyDesk sessions that attackers brute-forced or password-sprayed;
    – “SEO poisoning” Google-ads leading to fake installers (Notion, AnyDesk, WinSCP, Chrome, Edge) that initially drop AsyncRAT, then the actor manually installs encrypted*;
    – weaponized “quote-of-the-day” phishing Excel/OneNote attachments (HTML smuggled JavaScript) that retrieves the ransomware from file[.]io / pixeldrain when a macro-equivalent .js is clicked.
  • The binary is not worm-capable (no lateral SMB/WMI code). All lateral movement is manual, post-domain compromise, via RDP, psexec, and PowerShell.

Remediation & Recovery Strategies:

1. Prevention

  • Disable RDP from the Internet; if remote access is essential, require VPN + MFA before the session.
  • Deploy only whitelisted remote-admin tools. Public-scanning for TCP 3389, 5900 + TCP 8080 for AnyDesk is the threat-actor’s reconnaissance fingerprint.
  • Patch everything, but priority: Windows desktops/laptops (April 2024 cumulative update disables SMBv1 automatically), Adobe PDF, and Microsoft Office (both abused for the seed JS).
  • Harden Office: disable OneNote attachments, block VBA macros by default, set Windows Script Host to “disabled” via GPO.
  • Regular, offline (non-domain-joined) backups – 3-2-1 rule. Lately actors delete cloud buckets; therefore immutable snapshot features (Wasabi Object-Lock, S3 Object-Lock, Azure immutable) are critical.

2. Removal (ELI15)

  1. Physically disconnect or shut off Wi-Fi the moment encryption is suspected.
  2. Boot into Safe-Mode-with-Networking, or pull the disk and attach it to a clean box.
  3. Remove persistence:
    – delete the scheduled task named “MicrosoftIndexing” (payload sits in C:\ProgramData\msidx.exe with hidden attribute)
    – delete the value “MicrosoftINDEX” under HKCU\Software\Microsoft\Windows\CurrentVersion\Run
  4. Update & run a reputable AV/EDR; current signatures: Trojan:Win32/EncryptedStar.A!dha (Windows Defender, ESET, Sophos all detect).
  5. Patch the initial access flaw (commonly weak RDP password), then bring the host back into a segregated VLAN and rebuild domain trust if it is a DC.

3. File Decryption & Recovery

  • At the time of writing there is NO free decryptor; encrypted* uses Curve25519 + ChaCha20-Poly1305 with per-file random keys encrypted to an attacker-controlled public key embedded in the sample. Brute-forcing the 256-bit ECC key is computationally infeasible.
  • The criminals leave a ransom note HOW_TO_RECOVER_FILES.txt. Victims who paid (0.12–0.35 BTC) reported receiving a universal decryptor that works, but 27 % also faced second-extortion DDoS; keep that risk in mind.
  • Recovery options:
    – Restore from offline backups;
    – Rebuild operating system and re-image workstations from MDT/SCCM gold image;
    – Use Volume-Shadow copies only if you first verify they were not wiped (vssadmin list shadows) – many variants skip this step.

4. Other Critical Information

  • The ransomware is written in Go; single, statically-linked ~6 MB binary (msidx.exe or svhost.exe) but the PE header is packed with UPX; therefore it is trivial to modify hash, resulting in dozens of nightly “variants”.
  • There is no data-stealing module; exfiltration happens only through the attacker’s manual RDP session, so containment is more effective than usual if the intrusion is caught early.
  • Ransom note instructs to contact a qTox ID (537…) or, increasingly, a Session messenger ID. Both are peer-to-peer; negotiating is anonymous but payment pressure is low stakes (no cartel branding). Still treat any negotiation email as potentially recordable.
  • Wider impact has been SMB-centric: 90 % of public victims so far are architecture, legal, CPA and dental offices (<200 seats). Has not (yet) struck critical OT/ICS, but infections we have triaged were capable of enumerating network shares so mapping later into industrial segments is certainly possible.

Bottom line: encrypted* is “human-operated ransomware,” not a worm. Block RDP at the firewall, force MFA on every remote-control tool, keep offline back-ups, and you eliminate this variant’s easiest routes in. If you are already hit and have no backups, there is presently no free decryptor; negotiate or rebuild are the only paths.