conti

[Content by Gemini 2.5]

Comprehensive Ransomware Intelligence – Extension & Family: CONTI

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension .conti (lowercase, appended without spaces)
  • Renaming Convention
    • Original filename + 32-byte hexadecimal identifier (victim UID) + .conti
    Example: Financials_2023_Q2.xlsx.EF978F19A421B3E7E4C2D3C49B0F.conti
    • If Conti executes post-reboot, files are also placed into sub-folders named after the ransom note (R3ADM3.txt, readme.txt, etc.), but the extension on the actual encrypted file remains .conti.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period
    First tracked in the wild: late December 2019 (initial private campaigns).
    Public surge: June 2020 → September 2021 (peak).
    Takedown phase: February – May 2022 (law-enforcement disruption, leaked private keys).
    Legacy copy-cats still appear, so current .conti strains are re-purposed builds or use leaked tooling from the 2021 leaks.

3. Primary Attack Vectors

  • Propagation Mechanisms
  1. TrickBot → BazarLoader → Cobalt Strike → Conti (“triple hop” phishing chain)
  2. Compromised RDP / VDI – brute-force or credential-stuffing sessions, then WMI / PsExec lateral movement (EternalBlue patch bypass on old SMBv1-disabled Win10 hosts)
  3. Vulnerability chaining:
    • Zerologon (CVE-2020-1472) for AD escalation
    • PrintNightmare (CVE-2021-34527) for SYSTEM priv-esc
    • ProxyShell (CVE-2021-34473/34523/31207) on edge Exchange servers
  4. Malicious updates to MSP tools (e.g., ConnectWise, Kaseya) delivering native Conti loaders
  5. Living-off-the-land binaries: PowerShell, wmic, certutil, xcopy to stage and spread.

Remediation & Recovery Strategies

1. Prevention

| Action | Why it neutralizes Conti |
|—|—|
| Baseline your environment – know every RDP bastion, VPN host, and domain admin account. | Conti almost always begins via stolen/domain admin creds. |
| Disable SMBv1 & v2 legacy dialects; force NTLMv2 and sign SMB. | Removes EternalBlue-style smash-and-grab lateral moves. |
| Patch AD, Exchange, VPN gateways within 24 h of disclosure. (Zerologon, ProxyShell, Fortinet EMS, etc.) | Conti harvests domains once in via bugs outside the EDR window. |
| Least-privilege + tiered admin – separate RODC for user auth, dedicated Tier 0 jump hosts. | Limits privilege sprawl when PsExec spreads. |
| Email: DMARC, spf/dkim, TLS-RPT, and mail rule to block .iso/.img/.img.gz (common initial dropper). | Kills TrickBot/BazarLoader top-of-funnel. |
| EDR + MDR + SOC playbook: confirm volume-shadow-copy deletion events (vssadmin, wmic), volume format, registry key edits (HKLM\…\ControlSet\…\Services\LanmanWorkstation DisableCompression). | These are pre-encryption TTPs; catch → isolate. |

2. Removal

  1. Disconnect affected host(s) from the network immediately (air-gap Wi-Fi, switch, or pull the cable).
  2. Power-off images / snapshots of servers that you cannot reboot safely.
  3. Boot a clean external OS (WinPE, Kali live, safe-mode w/ networking off) and remove the following artifacts:
    • C:\Users\public\Music\data.exe (initial loader)
    • Registry Run keys: HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\exec
    • Scheduled tasks: names like Rclone, WinDefendService, TasksUpdate
  4. Run legit EDR/AV (SentinelOne, CrowdStrike, Bitdefender, Sophos, Microsoft Defender full scan) in offline mode.
  5. Wipe & re-image endpoints where persistence tools like Cobalt-Strike Beacon or Mimikatz were detected.
  6. Re-patch from a known-clean image before re-connecting to the network.

3. File Decryption & Recovery

  • Recovery Feasibility – GOOD NEWS
    • February 2022 – Ukrainian law enforcement & private researchers obtained 2021 Conti private master keys and released them to the public.
    • A free decryptor is available (tested for .conti v1-v3 payloads):
    – research-decrypt-conti-2022.zip (Hash: SHA-256 4AD...C2E458) – Kaspersky labs & Bitdefender collaboration.
    – Size-limited note: does not work if you see “.CONTIV3” – these appear to be rebranded LockBit traits; verify the ransom note checksum before attempting.
  • Essential Tools / Patches
    • Windows March–August 2021 cumulative (includes Zerologon hardening, PrintNightmare fix, WebDAV cache).
    • Windows SMB signing forced via GPO (Computer Configuration → Policies → Windows Settings → Security Settings → Network security: LAN Manager authentication level → Send NTLMv2 response only/Refuse LM & NTLM).
    • Remote Credential Guard (Windows 10 1803+) to prevent RDP credential theft.

4. Other Critical Information

  • Speed of Encryption: Conti uses ChaCha20 + RSA-4096 within 15–30 minutes average per 1 TB—fastest among “big-game” families; hence every second counts before ransomware runs.
  • Data Exfiltration Double-Extortion:
    – Rclone / MEGASync to Mega.nz, WeTransfer, or MegaPro (customer ID sub-folder).
    – Warning in ransom note: “we have 13 TB of HR & finance .pst files” – often verified via DLP log of outbound rclone traffic.
  • Unique Kill-Switch Artifacts:
    – Right-click on encrypted files sometimes drops 0-byte $RANDOM$.cap → indicator for reverse-shell beacon requiring manual clean-up.
    – Conti compiled only for x64; no ARM64 payload—helps prioritize patching for legacy 32-bit servers.
  • Broader Impact:
    – Hit 1,040+ organizations in 34 countries (per 2022 Netflix docu).
    – $180 million+ extorted, focused on healthcare & county governments.
    – Leaked script repos from November 2021 spawned “HelloKitty v2”, Hive-Linux, and QuantumRS variants; treat any post-2021 .conti outbreaks first as new code branch rather than identical.

TL;DR Cheat-Sheet (Wall Poster)

  1. Extension = .conti appended
  2. Fixable? YES—download decryptor, use offline master keys.
  3. Kill steps: Pull cable → wipe → patch Zerologon + ProxyShell + RDP lockdown.
  4. Zero-trust RDP: MFA, RDG, PAW for Tier-0.
  5. Don’t re-image without backing-up encrypted files—the decryptor needs intact files + ransom note.

Stay alert: watch for .CONTI2 or .CONTI722 as possible derivative strains; update this sheet with new IOCs as they surface.