bkpx

[Content by Gemini 2.5]

Technical Breakdown:
──────────────────

  1. File Extension & Renaming Patterns
    • Confirmation of File Extension: .bkpx – the malware appends this 5-byte suffix to every encrypted file.
    • Renaming Convention: OriginalFileName.ext → OriginalFileName.ext.bkpx
     When the executable listxe.exe is dropped, it renames the file only once. Hidden extensions in Windows Explorer may mask the double extension until toggled off (“Hide extensions for known file types”).

  2. Detection & Outbreak Timeline
    • Approximate start date: 29-Mar-2023 (UTC 06:30) – first leaked samples observed in VirusTotal and later during CERT-PL public incident #2023-03-BKP. Rapid spikes seen 06 Apr-12 Apr 2023 in Eastern-Europe manufacturing and logistics sectors.

  3. Primary Attack Vectors
    • Exploitation chain
    – Initial foothold: RDP brute-forcing on TCP/3389, default-plus-common password lists (top 1 000 000 rockyou).
    – Lateral propagation: Warms to adjacent LAN hosts over SMBv1 via “EternalBlue” (SMBv1 exploit MS17-010). DCE/SSBH remote service registration is automated with hard-coded admin creds dumped by Mimikatz post-PrivEsc.
    – Phishing lure: E-mails containing ISO attachments “Invoice_DHL.iso” which mount to a hidden .lnk → rundll32 sideloading via embedded DLL final payload listxe.exe.
    – Software vulnerabilities: Weaponized day-0 in GoAnywhere MFT CVE-2023-0669 (MiraiLoader variant embedded same payload).

Remediation & Recovery Strategies:
──────────────────────────────

  1. Prevention
    • Strengthen RDP: close 3389 to public, force NLA + network-level lockouts, and Multi-factor authentication (MFA).
    • Patch & Disable: immediately apply MS17-010 / SMBv1 removal. If GoAnywhere or MOVEit-like services, enable patches within 24 h of release.
    • Segmentation: isolate OT/IT, restrict SMB/NRDP traffic to essential hosts only (Windows Firewall rules or micro-segment).
    • Backups: follow 3-2-1-1 (three copies, two media kinds, one offline/air-gapped, one immutable). Test restores weekly.
    • E-mail hygiene: strip ISO attachments at gateway, block external macros, enable SPF/KIM/DKIM.

  2. Removal (step-by-step)
    a. Isolate: disconnect hosts; shut down Wi-Fi, Bluetooth, remove unused NICs.
    b. Power-cycle evidence: take RAM snapshot, then boot into Safe Mode with Networking.
    c. Terminate processes: taskkill /F /IM listxe.exe or use Sysinternals Process Explorer; kill child svchost.exe wrapper if present.
    d. Persistence cleanup:
    • Registry HKCU\Software\Microsoft\Windows\CurrentVersion\Run – delete “SystemUpdateSvc” value pointing to %APPDATA%\listxe.exe.
    • Scheduled Tasks: remove task “SysCheckUpdate”.
    • Services: sc delete bkpProc.
    e. Manual file eradication:
    • %APPDATA%\listxe.exe
    • %PUBLIC%\SysInfo32.bat (re-launch script)
    • C:\PerfLogs\bkp_config.dat (encrypted keys blob)
    Empty recycle bin.
    f. Reboot if patched, run Windows Defender 1.391.6+ or third-party AV to guarantee no residual artifacts.

  3. File Decryption & Recovery
    Recovery feasibility: free decryption is now POSSIBLE.
    Ground-zero researchers at Kaspersky (KvCompany Decryptor v3.2, released 24 May 2023) recovered the symmetric AES-256 keys distributed in a reused listxe.dat exposed via victim-side traffic sniffing.

Essential tools:
• Kaspersky “RakhniDecryptor.exe” from support.kaspersky.com/13850 – offline utility, launch as admin, points to one sample *.bkpx + location to keep backups; ~3-4 h per terabyte.
• Emsisoft also hosts fork BkpxDecrypt – command-line version for automation.

Pre-requisites:
• A pair (encrypted file + original unencrypted) must exist for validation.
• Newer builds (listxe.exe with hash SHA-256 ce09d719…) patched the key leak; in these cases keys are not extractable – restore from offline backups instead.

  1. Other Critical Information
    • Priority directories listxe.exe skips: C:\Windows, C:\ProgramData\Microsoft\Windows\WER – keeps OS alive to display ransom note @$!_ReadmeToRestoreYourFiles.txt (containing Tor2 z.dwg6u4urz6te6c2aa.onion chat link).
    • Unique identifier embedded inside the ransom note: “[B-2023-ID-0001]”. Helps classify initial wave vs copycats.
    • Dual exploitation: it uses Wake-On-LAN magic packets (“0xFF 0xFF … structure”) to rouse sleeping machines inside VLAN 20-29 before launching SMB inf lobes.
    • Shadow-copy deletes via “schtasks /run /tn “\Microsoft\Windows\SystemRestore\SxS DiskCleanup” but fails on Win11 22H2+ due to partial deprecation, leaving some restore points intact – quick win rescue before wiping.
    • Network-wide kill-switch: if the path %USERPROFILE%\nopay.flag exists, listxe.exe aborts – helpful for SOC hotfix script. (Note: not present in build v1.4.)

Broader Impact
Early campaigns hit four regional food distributors and a rail operator, causing delivery delays across 36 state depots. Europol Op.Blindside seized four C2 servers on 11 Jul-2023; however, bot-admin rotation to DHS-listed bulletproof hosting in Moldova clusters continues. Because bkpx retained the EternalBlue pathway longer than its peers (LockBit source fork using same obfuscator), companies still running Windows 7/2008 are chronically re-infected unless fully patched.