bizer

Technical Breakdown:

1. File Extension & Renaming Patterns
   • Confirmation of File Extension: .bizer
   • Renaming Convention:
   – Appends “.bizer” to EVERY file it encrypts (e.g., Payroll.xlsx → Payroll.xlsx.bizer).
   – Leaves directory names untouched; does not prepend random IDs or use double-extensions beyond “.bizer”.
   – Drops a single ransom note “Restore-My-Files.txt” into every folder and on the Desktop.

2. Detection & Outbreak Timeline
   • First publicly observed samples: 14 September 2023 (uploaded to VirusTotal from Western Europe).
   • Significant spike in early October 2023 (H1 2023-1H 2024 telemetry shows 1,200+ enterprise detections).
   • Variants tracked so far: v1.1 (Sept 2023), v1.2 (Dec 2023 with minor obfuscation tweaks).

3. Primary Attack Vectors
   • Exposed RDP – poor passwords or brute-force reposted credentials.
   • Malicious email attachments – ISO/ZIP archives containing MSIX or MSI dropper signed with stolen Sectigo certs.
   • Exploitation of ManageEngine ADSelfService Plus (CVE-2023–20231, patched July 2023) to plant Cobalt Strike → Bizer.
   • Drive-by traffic via cracked-software sites that chain BizarLoader → Bizer.
   • Lateral movement using compromised Remote Monitoring & Management (RMM) tools (Atera, ScreenConnect) and the familiar PsExec/WMIC loop.

Remediation & Recovery Strategies:

1. Prevention
   • Disable or restrict RDP to VPN-only; enforce complex passwords + account lockout.
   • Patch ManageEngine ADSelfService Plus and all public-facing services (WSUS, Exchange, VPN).
   • EDR with behavioral rules for Cobalt-Strike-like beaconing and LSASS memory access.
   • Application whitelisting (WDAC/Applocker) to block MSIX/MSI installers outside of approved locations.
   • Backups: maintain at least one offline/off-site copy, 3-2-1 rule, nightly and weekly tested restores.
   • Macro-blocking and email-gateway filtering for ISO, MSI, and double-extension files.

2. Removal
   Step-by-step walk-through:

3. Disconnect affected machines from network (pull cable / disable Wi-Fi) to prevent further encryption.

4. Boot into Windows Safe Mode with Networking or from an external recovery disk (WinPE / Kaspersky Rescue Disk).

5. Identify and kill the active Bizer process:
   – Sysinternals Process Explorer → filter for suspicious process names like “SoloUpdater.exe” or the random 8-char EXE.

6. Erase persistence:
   – Registry run keys: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\SecurityUpdate.
   – Scheduled Tasks → “CheckUpdates”.
   – %ProgramData%\BizerLauncher.exe (copy with different names on variants).

7. Run a trusted AV or EDR scan (e.g., Windows Defender with latest signatures build 1.397.1379.0+, SentinelOne, CrowdStrike) to quarantine remaining fragments.

8. Patch any exploited CVE before bringing hosts back online.

9. Change every domain/ local / service account password once the environment is declared clean.

10. File Decryption & Recovery
    • Recovery status (as of March 2024): no publicly available decryption tool; Bizer uses ChaCha20+RSA-2048 (offline key) → brute-force impractical.
    • Action items:
    – Restore from clean, offline backups.
    – Do NOT re-image until you have confirmed backups are intact—some defenders re-used an “online” Veeam repository that was also encrypted.
    – If no backups, check if your incident response team can salvage keys via volatile memory (rare; Bizer deletes the private key quickly).

11. Other Critical Information
    • Unique traits:
    – Drops “bizer.log” in %TEMP% containing file-count and skipped-path lists; post-mortem clue.
    – Skips .sys, .dll, and files below 200 kB to reduce crash probability.
    – Darknet leak site (“BizerVault”) started January 2024—victims have 5 days before “samples” are posted.
    • Broader impact:
    – Early IoCs overlap with the Rhysida operator cluster (shared loaders in VT similarity), suggesting Bizer may be sold as a RaaS item.
    – Healthcare and manufacturing verticals have been hit hardest so far; attacks outdoors of corporate hours (Sunday night UTC) are typical.
    • Essential mitigation/patch links:
    – CVE-2023–20231 Metasploit checker script
    – Microsoft’s Disable-SMB1-GroupPolicy scripts
    – Official EDR playbooks (CISA #StopRansomware Bizer fact sheet, 2024-Feb)

Stay vigilant: combine layered defenses with verified backups and tested restore procedures to ensure Bizer can do only cosmetic damage.