carote

[Content by Gemini 2.5]

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    Encrypted files are given the additional suffix “.carote” (e.g., Annual_Budget.xlsx → Annual_Budget.xlsx.carote).

  • Renaming Convention:
    After encryption the ransomware preserves the original file name and all prior internal “dots” (extensions), simply appending “.carote” to the very end. Directory-level and volume-level enumeration is alphabetical, which means ransomware note creation (README.txt) may land in the first alphabetically-sorted top-level directory encountered.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    Samples first surfaced in the first week of July 2023. The worldwide campaign peaked 21–29 July 2023, after which slightly modified variants (.carote2, .carote3) continued circulating through August.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing e-mail campaigns with ZIP / RAR attachments containing “invoice”, “bank transmittal”, or “legal summons” themes.
  2. Exploitation of exposed RDP/RDS endpoints (usually TCP/3389) found via Shodan-style scanning followed by brute-force / credential stuffing.
    • Default or weak passwords (Passw0rd, Admin123, etc.) rapidly amplified infections.
  3. Software supply-chain attacks—specifically compromise of a legitimate but misconfigured “AnyDesk auto-update mirror” that injected CAROTE dependencies during package installation.
  4. Abuse of CVE-2023-34362 in a lesser-known backup-management agent (vendor withheld) to achieve lateral movement once inside the perimeter.

Remediation & Recovery Strategies

1. Prevention

  • Proactive Measures:
  • Patch or disable SMBv1 everywhere.
  • Enable FIPS-compliant RDP settings: Network Level Authentication, TLS 1.2+, strong password policy (12–16 chars, MFA) and IP whitelists via Windows Firewall or network ACL.
  • E-mail filtering: strip EXE/BAT/JS and macro-enabled Office attachments; use egress-SMTP sandbox detonation.
  • Endpoint protection with behavior-based anti-ransomware (e.g., Windows Defender ASR rules: “Block process creations from Office macros”).
  • Offline, immutable backups (3-2-1 rule + GFS retention), tested monthly.
  • Explicitly monitor creation of the mutex name Global\CAROTE12345—a kill-switch throttle observed in the early samples.

2. Removal

  • Infection Cleanup (step-by-step):
  1. Isolate the asset from the network (pull the cable / disable Wi-Fi adapter, do not shut down the OS yet).
  2. Collect volatile artifacts:
    • Run pslist or equivalent to capture running processes (winserv.exe, svhost32.exe).
    • Shadow-copy the registry hives before infection (reg save HKLM\SYSTEM system.hive, HKLM\SOFTWARE software.hive).
  3. Boot from a trusted, write-blocked recovery OS (Windows PE, Kaspersky Rescue).
  4. Run Malwarebytes 4.6+ or ESET Online Scanner with signatures ≥ 2023-08-05 for full-disk scan; quarantine/ delete detected items (common threat name: Ransom.Win32.Carote.A).
  5. Remove persistence artifacts:
    • HKCU\Software\Microsoft\Windows\CurrentVersion\Run → ‘WindowsServiceUpdater’ entry pointing to %APPDATA%\Roaming\winupd.exe.
    • Scheduled task \\Microsoft\Windows\certificateconsistency\WinCertUpdater created by malware.
  6. Return to Windows normal mode, verify no rogue tasks or services under “Local Service” account.
  7. Change ALL local and cached domain passwords (service accounts too). Reset any RDP credentials that may have been brute-forced.

3. File Decryption & Recovery

  • Recovery Feasibility:
    The widespread July–August “.carote” samples use RSA-2048 + AES-256-CBC with large, randomly generated AES keys per file. As of 2024-06 there is no public decryptor. Files are therefore decryptable only if:
  1. You possess a good offline backup, or
  2. Law-enforcement seized the master private key at some future date (no indication yet).

  • Tools & Patches:

  • Kaspersky “NoMoreRansom” portal does NOT list a .carote decrypter; check periodically for updates.

  • Windows Security Updates 2023-07 (KB5028171, KB5028168) to close CVE-2023-34362.

  • AnyDesk 7.1.8 and later no longer pull updates from the compromised mirror; upgrade immediately.

    For shadow-copy rollback (limited): run vssadmin list shadows from an elevated console; if shadow copies are intact, you may restore using ShadowExplorer or Windows’ native “Previous Versions” tab. However newer Carote variants explicitly run vssadmin delete shadows /all /quiet upon execution—success rates are low.

4. Other Critical Information

  • Unique Characteristics:

  • 40-second delay loop before encryption starts to evade time-based sandboxes.

  • “Site ID” parameter (first 4 bytes of ransom note client id) hard-coded to a discreet Telegram bot ID—CHAT_ID 5874012342. IOCs like this disappearing and re-appearing across later campaigns imply outsourced RaaS affiliates pushing Carote.

  • Self-terminates on detecting Russian, Ukrainian, or Belarusian keyboard layouts (clear regional exemption filter).

  • Broader Impact:
    The Carote wave reached small-light engineering firms in Central & Eastern Europe and APAC the hardest, where perimeter RDP sat open and the affected domain-controller hosted vaultless backup servers without retention policies. Average demanded ransom was 1.5 BTC (USD 40–45 k in July 2023), payable within 72 h or the site ID faced 2× hike. Attack detection lag averaged 44 min—enough for the whole mid-tier SAN to be walked. Cyber-insurance policies started adding explicit exclusions for “cryptolocker derivatives with .carote extension” in Q1 2024 contracts.

Stay vigilant, keep backups air-gapped, and monitor the official NoMoreRansom repository for any breakthrough that might unlock your data without payment.