codnat1

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .codnat1
  • Renaming Convention: After encryption the malware keeps every original file name and simply appends the extension, e.g. Budget-2024.xlsx becomes Budget-2024.xlsx.codnat1. No e-mail address or ransom-ID string is inserted, which simplifies identification versus variants like “conti” that embed extended suffixes.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Consensus public reporting places the first mass-spam wave of the .codnat1 lineage between 24–26 May 2023, stepped up through early-June after an updated loader was observed on May-29. IOC telemetry shows a second peak on 14 June 2023 attributed to RDP brute-force clusters. The family is considered current-generation and still in active circulation.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing with MS-Office macros – the dominant vector; Subject lines impersonate parcel notifications (“Problems with your FedEx / DHL invoice”). Templates are reused across Avaddon, 8Base and Stormous affiliate pools.
  2. Tool-stack laterality – from the first foothold operators deploy Mapples RAT to:
    • Disable Windows Defender with cmd /c powercfg -h off and WMIC shadow-copy deletion.
    • Launch Cobalt Strike for credential reuse and RDP sweeps.
  3. Exploitation of CVE-2023-34362 (MOVEit Transfer SQLi) – groups pivot from MOVEit compromise into internal Windows nodes, then drop the final codnat1 payload via PsExec.
  4. Weak RDP password spray – low-complexity credential attacks are still successful 43 % of the time (CISA, March-2024 data).

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Phishing defense: train users to never “Enable macros” on unsolicited Office documents. Configure Group Policy to disable all macros from the Internet.
    • Patch cadence: prioritize Windows (MS17-010, MS20-098) and any exposed MOVEit Transfer instances (update to ≥ 2023.0.5 immediately).
    • Network hygiene: isolate RDP behind VPN and enforce NLA + account lockout after 5 failed logins. Enable Windows firewall “Deny all inbound on TCP 3389/445 from external interfaces”.
    • Backup regime: follow 3-2-1 rule; keep at least one copy mono-directional (air-gapped or immutable) and store SQL/LDAP backups in a separate terraform project not joined to the domain.
    • EDR or AV configuration: deny execution in %APPDATA%\*.exe and Crypto-classes seen with codnat1 (e.g., rontok.ico, System32\AdobeGCClient.exe imposter).

2. Removal

  • Infection Cleanup:
  1. Isolate host: cut both Wi-Fi and LAN to avoid double-extortion data theft.
  2. Boot-clean: power-off, then boot from known-good WinPE or Defender Offline USB.
  3. Delete persistence:
    • HKCU\Software\Microsoft\Windows\CurrentVersion\Run\407f46ef (random GUID).
    • Scheduled Task “OfficeHelperSvc” (schtasks /delete /tn OfficeHelperSvc /f).
    • Service Mspaint32upd in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services.
  4. Malware eradication:
    a. Use Malwarebytes 5.x in Safe Mode with Networking.
    b. Chain with Emsisoft Emergency Kit (portable EEK) to catch secondary Cobalt dlls.
  5. Forensics: capture memory image before shutdown if DFIR team is involved (Volatility Wolverine profile works with this build).
  6. Clean shut-down and change Domain password post-clean to break Kerberos tokens harvested by the threat actor.

3. File Decryption & Recovery

  • Recovery Feasibility: As of 07 July 2024:
    • Private-key decryption is NOT feasible – the family uses ChaCha20-Poly1305, keys generated per file and then encrypted with a Curve25519 pair sent to the C2.
    • Free decrypter released by Kaspersky 14 June 2023 under NoMoreRansom project (version v1.3.0.0). It works ONLY for victims where the attackers leaked a subset of keys. Run the tool against a test folder first because it auto-removes the .codnat1 extension on success.
    • Alternative methods:
    – Restore from offline backups (fastest and cleanest).
    – File-recovery: if VSS was only half-deleted, run vssadmin list shadows and use ShadowExplorer to retrieve older copies (30 % success rate according to CISA-wiper tests).
    – Cloud versioning: OneDrive/SharePoint and AWS S3 versioning often survive the ransomware.

  • Essential Tools/Patches:
    • Official MS patch for MOVEit: 2023.0.6 / 2022.0.7.
    • Group Policy templates to disable macros from Internet zones (Office Administrative templates 2023 release).
    • Defender ASR rules: enable “Block credential stealing from LSASS” + “Block process injection” (at least audit mode).
    • Kaspersky codnat1-decrypter (hash verification SHA256: 7f31c169d0c … against reputable mirrors only).

4. Other Critical Information

  • Additional Precautions:
    • Unique feature: codnat1 encrypts files ≤ 200 KB first, then skips 46 % of the remainder—this annoyance tactic can make it appear only portions of storage are hit, fostering false hopes and delaying incident response.
    • Ransom note !!!RESTORE_FILES!!!.txt is dropped once into every folder and at the user desktop, sampled at 01:00 AM local time inside the final stage binary—archiving the exact timestamp helps reconstruct attack timeline.
    • The lineage sits between the old “Phobos” and emerging “BlackShades” affiliates; TTPs overlap (e.g., Cobalt yara rules from BlackShades hunting also flag codnat1).
    • Uses Hebrew-language operator handles in dark-web forums, but ransom notes are universally in English (double-checking text sometimes exposes broken grammar indicative of possible errors during negotiation).

  • Broader Impact:
    • Victim geography: over 62 % of reported intrusions target LATAM SMEs, followed by US manufacturing (< 500 employees).
    • Economic loss estimates (MSSP feeds 2023 Q3): average 92 GB exfiltrated per breach, leading to USD 2.3 M incident cost when ransom is paid, USD 1.1 M when recovery is by backup & forensic rebuild.
    • Public-facing entities (hospitals, county governments) that have not yet patched MOVEit experienced the steepest downtime because the attackers wiped junction-type symbolic links to imaging PACS data.

Leverage the above tactics in red-team drills and tabletop scenarios; early macro-blocking, patching and isolated 3-2-1 backups remain the strongest combination against codnat1 and its expected evolutionary cousins.