btcbtcbtc Ransomware – Comprehensive Threat & Recovery Guide

Contributed by: Cybersecurity Incident Response Team (anonymous)

Technical Breakdown:

1. File Extension & Renaming Patterns

Confirmation of File Extension: .btcbtcbtc
The extension is appended after the original file extension, producing names like document.xlsx.btcbtcbtc, blueprints.dwg.btcbtcbtc.
Renaming Convention:
Victim’s original file name and extension are preserved in full.
Each folder containing encrypted files will also receive a RESTORE_FILES_INFO.txt (or .hta variant) ransom note; the malware deliberately avoids touching critical Windows and browser folders to keep the system running while holding data hostage.

2. Detection & Outbreak Timeline

Approximate Start Date / Period:
First public sightings: March 2024, with a far larger surge between April–June 2024.
Advertising campaigns on underground forums began one week before the outbreak, indicating active deployment by an affiliate program.

3. Primary Attack Vectors

| Vector | Typical Payload / Example |
|—|—|
|Exploitation of Remote Desktop Protocol (RDP)| Brute-force on exposed 3389/TCP, followed by credential stuffing and lateral movement to domain controllers. |
| Phishing via MSI & ISO “invoice” lures | ZIP > ISO > Setup.msi containing btcbtcbtc dropper signed with stolen, expired code-signing certs. |
| Utorrent & warez cracks | Torrent locker “AdobeAcrobat2024_Crack.exe.exe” installs both the ransomware and a secondary infostealer. |
| Browser-exploit kits (Chrome/WebRTC zero-day) | Chrome v124 unpatched builds auto-dropped the loader in %TEMP%\chrome_updater.exe. |
| PowerShell / WMI abuse | Post-breach scripts disable Windows Defender real-time, clear event logs, and fetch final stage payload from Discord CDN URLs. |

Notes: btcbtcbtc frequently uses “Living-off-the-Land binaries” (lolbins) such as rundll32.exe, certutil.exe, and cert-store bypass tricks {01575CFE-9A55-4003-A5E1-F38D1EBBE204} to avoid AV heuristic signatures.

Remediation & Recovery Strategies:

1. Prevention (Do these now)

| Action | Rationale |
|—|—|
|Block inbound RDP (port 3389) at the firewall or restrict via VPN only.|80 % of enterprise infections traced to “wide-open” RDP.|
|Enforce local admin password randomization (LAPS) + MFA everywhere.|Stops credential re-use inside network.|
|Apply current Windows cumulative update (May 2024 or later). Includes fix for the RDP-based CVE-2024-26130 abused by btcbtcbtc.|
|Disallow “execution from %TEMP%” via Applocker / WDAC policy.|
|Enable Controlled Folder Access (CFA) and Microsoft Defender ASR rules.|Blocks tampering attempts outside of whitelisted processes.|
|Disable Office macros via GPO and force Mark-of-the-Web to block ISO, JScript, and MSI drive-by execution.|Cuts off major gst email vectors.|

2. Removal (Step-by-Step)

Isolate Immediately: Disconnect the affected host from all networks—pull the cable or disable Wi-Fi & Bluetooth.
Boot into Safe-Mode Networking Disabled (Windows 10+ Hold-shift Restart > Troubleshoot > Startup Settings).
Scan with Offline Toolkit: Boot from a reputable rescue USB (Bitdefender Rescue CD, ESET SysRescue, Kaspersky Rescue Disk) and perform full system scan. Detected family definitions will be Ransom:BTCBTCBTC or Ransom:Win32/BtcDelta.A.
Manual Checks:

Delete scheduled tasks created in C:\Windows\System32\Tasks\ named SysHelper, OneDriveUpdate, gupdate.
Remove service SysUpdate (display name “HostNetPro Service”) via sc.exe delete SysUpdate.

Patch & Harden:

Remove stale local user/service accounts with wmic useraccount where "name='SrvSys' and sid like 'S-1-5-21%'" delete.
Apply latest cumulative Windows update; change any reused domain admin passwords.

3. File Decryption & Recovery

Recovery Feasibility & Methods:
NO universal decryptor is currently available. The ransomware uses ChaCha20 + Curve25519 (similar to Conti V3) with a securely generated victim-specific master key that is never exposed on disk.
Have backups? Use offline, read-only backups or snapshots (Veeam, Nakivo, ZFS) and re-image machines according to your incident runbook—this is the safest path.
File-scraper QNAP/Synology? If NAS shares were encrypted, check for .@SynoResource. btrfs snapshots may still contain intact data; run sudo btrfs sub list -p /volume1/.
Shadow Copies? btcbtcbtc explicitly deletes VSS (vssadmin delete shadows /all)—but some older shadow-scanner utilities (ShadowExplorer, vssadmin list) occasionally miss CBT snapshots. Worth a 1-minute check.
Community Repos: At the time of writing no free key-reuse or binary-flaw has been discovered; ignore YouTube “.btcbtcbtc decryptor” scams.

4. Other Critical Information

Unique Characteristics:
btcbtcbtc encrypts over UNC paths, DFS shares, and ESXi NFS datastores; remember to check VMware datastores (/vmfs/volumes) as VMs can look unbootable.
Delivers a double-extortion payload: threat actors simultaneously exfiltrate via Mega.nz, MEGA SDK “setup_debug.exe”. Victims receive individual leak-site profiles if ransom not met.
The binary appends a 120 byte footer containing the victim ID, curve25519 public key, and checksum—ransom note filenames are “semi-unique” for tracking.
Broader Impact:
More than 1200 known incidents in US & EU healthcare alone (Q2 2024) according to the Health-ISAC feed. Indelible reputational impact for university research labs due to guaranteed breach notifications via leak-site.
Affiliate payouts start at 25 % of ransom demand—ensuring sustained distribution across different spam affiliates.

Emergency Quick-Reference

Stay safe—don’t pay the ransom if alternatives exist.