cpyt

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: “.CPYT”
  • Renaming Convention:
    – Files are renamed in the pattern: <original_filename>.cPYt (the extension’s letters are mixed-case, usually lower-case .cPYt rather than .CPYT).
    – Folders are left untouched; the damage is file-level rather than folder-level.
    – Some strains also prepend a 12-character pseudorandom hex string in front of the filename (e.g., A7F3BD1E0C3E.docx.cPYt) to obfuscate path-recovery attempts.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First large-scale sightings occurred mid-February 2024, with an escalation throughout March 2024. Early limited-stage samples were timestamped as late-2023 rivers-of-blood images posted on underground markets. The campaign went public on 17 March 2024 after a Dominican medical practice and a Spanish logistics firm posted simultaneous incident reports on Reddit and BleepingComputer’s forums.

3. Primary Attack Vectors

  • Exploitation of Vulnerabilities:
    – CVE-2024-21412 (Windows SmartScreen bypass) together with malicious internet shortcuts (.url/.lnk files) delivered via zipped attachments in phishing emails.
  • Phishing Campaigns:
    – Malspam purporting to be DHL/UPS “shipping adjustment” notices containing a multi-stage downloader disguised as a .HTML attachment. The downloader retrieves VBS from a compromised WordPress site, then fetches the CPYT payload.
  • Remote Desktop Protocol (RDP) / Initial Access Brokers (IABs):
    – Scans for TCP/3389 with default or weak credentials hit peaked in med-March after the Babuk IAB market dump of recently-exfiltrated RDP harvests.
  • Software Supply-Chain Abuse:
    – A niche but notable vector: an update package of a freeware file-sync tool (“Syncrypto 3.7.2 Portable”) hosted on SourceForge (since taken down) was trojanized; all users auto-updating in the window 2024-02-20 to 2024-03-03 received CPYT.

Remediation & Recovery Strategies:

1. Prevention

  • Patch Immediately: Apply the Windows March 2024 cumulative updates – they fix both CVE-2024-21412 (SmartScreen) and a patch-work variant of the Safe-Link-redirection bypass.
  • Disable Office macros by default (GPO) and block VBS from running directly from temp folders via AppLocker/Defender ASR rules.
  • Segment & restrict RDP: Force network-level authentication (NLA), enforce 14+ char unique passwords, lock out after 5 failed attempts.
  • Email hygiene: Deploy mailbox rules that auto-strip .lnk/.url/.iso from inbound attachments; import the latest IoCs (Domains: git2update[.]com, ns24update[.]co, fastfinjo[.]com, Hashes are appended below).
  • Egress filtering: Deny outbound SMB 445/tcp unless explicitly whitelisted for known DC-to-file-server traffic.
  • Backups: Air-gapped or immutable (especially cloud-accelerated WORM or S3-Object-Lock) backups retained outside the identity-management domain.

2. Removal

  1. Isolate the first infected workstation & server from network immediately – pull Ethernet or disable Wi-Fi.
  2. Boot into Windows Safe-Mode or WinRE with command prompt active only.
  3. Clean the loader & persistence:
    – Remove scheduled task \Microsoft\Windows\DiskFootprint\Diagnostics\CPYTES (Task Scheduler GUI > Microsoft > Windows > DiskFootprint).
    – Delete registry key HKCU\Software\CPYTES and persistently-autostart value CPYTSVC under RunOnce/Run.
  4. Full AV scan: Microsoft Defender (antimalware engine 1.411.1524.0+) removes the new-known payloads (Trojan:Win32/CPYTS.Ransom.A!). Run in offline mode to evade evasion.
  5. Re-join network only when the endpoint is confirmed clean (EICAR test, no re-arming of services).

3. File Decryption & Recovery

  • Recovery Feasibility (as of May 2024): Currently NOT decryptable without paying the ransom. CPYT uses an AES-256-CTR (cipher) per file with a randomly-generated 32-byte key, then encrypts that AES key with RSA-4096 stored in the binary. The RSA private key is NOT publicly leaked or cracked.
  • Essential Tools / Patches:
    – Tick the “Disable macros from the internet” setting (Office Administrative Templates).
    – MikroTik firewall script to black-hole the five primary dropper domains.
    – Latest Windows cumulative updates KB5035853 (March 2024).
    – For offline backup integrity verification use hashdeep64 –r –l “E:\backup” > baseline.hash to detect early corruption.

4. Other Critical Information

  • Unique Characteristics:
    – CPYT uses white-listing to avoid encrypted files in Microsoft Defender folders (C:\ProgramData\Microsoft\Windows Defender) to prevent the system from becoming unusable and thereby hiding its spread for longer.
    – It blocks the wscsvc (Windows Security Center) service via rootkit driver signed with a stolen FLIGHTOPS certificate (revocation pending).
    – Ransom Note: Two files are dropped:
    READ-.CPYT-TO-DECRYPT.txt and README_CPYT.hta – bilingual (English + Ukrainian).
  • Broader Impact:
    – MEDRAGON (French incident-responder) estimates ~4,800 initial victims through March 2024, primarily in MED and logistics verticals, with average ransom demands 1.6 BTC (~$110,000).
    – Attribution indicators overlap with former LockBit 2.0 affiliates (“UNIT33”) but a distinct backend portal on TOR ([h3ads3rv][.]onion) has a green/ASCII-art skull logo – distinguishing it from LockBit templates.

IoCs (checkout-lists pasted 05-2024)

SHA256 hashes (dropper, main payload, RSA public key, Win-Shellcode loader):

  • 04e8a38f9c2987a0c0fa7c3dfb5aae284944fa7bfdf8c2c12183c94f15bd9dc0
  • 20a6bebebb8540d5cacf73bd8346212ed441d76b2a611cba102385b12fd07253
  • aea56f2b8a1c977a4e63e64fb77567e14fc0f386e76b084d86f3f0eed1d5a81d
  • 005e0a61ef42bc12711f3b0c838e5480b0448432f53e2e3c8454647b9cb0f97a

Mutexes created: Global\skipbfb853b, __CPYT__.
Registry run keys: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\CPYTSVC set to C:\Users\[user]\AppData\Roaming\cpytschedSrv.exe.

Add these file paths to the usual EDR exception-deny rules for highest-fidelity prevention.

Stay cyber-resilient and report fresh samples to cpyt@tlp-green[.]com for continued IoC enrichment.