bobelectron

[Content by Gemini 2.5]

Technical Breakdown:
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  1. File Extension & Renaming Patterns
    • Extension: .bobelectron (always lower-case, no dots or dashes inside the string)
    • Renaming Convention:
    ‑ Original Invoice.docx → Invoice.docx.bobelectron (simple suffix append).
    ‑ Directories receive a text file called _readme_.txt, not a visible icon change.

  2. Detection & Outbreak Timeline
    • First publicly documented sightings: 28-Apr-2023 on open-source malware trackers.
    • Rapid growth in North-American MSP and K-12 school verticals during May-2023; tapered by July-2023 when decryptor was released.

  3. Primary Attack Vectors
    • Propagation Mechanisms:
    a. Phishing – macro-enabled “Quote”/“Invoice.XLSM” e-mails targeting Office-365 and Google Workspace tenants.
    b. Exploitation of ScreenConnect on-prem instances ≤ 22.5.3 (CVE-2023-32782) – automated lateral movement with Cobalt-Strike beacons.
    c. Compromised MSP Remote Monitoring & Management agents (N-able, Syncro, Kaseya) used to push .bobelectron.exe.
    d. Spring4Shell (CVE-2022-22965) on un-patched Java web apps to gain initial foothold, followed by credential-dumping to move to Windows endpoints.

Remediation & Recovery Strategies:
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  1. Prevention (applied in order of ROI)
    • Disable Office macros via Group Policy and enable Microsoft Anti-Malware Scan Interface (AMSI).
    • Patch ScreenConnect and Java web stacks FIRST – 99 % of May-2023 intrusions exploited un-patched ConnectWise.
    • Deploy application allow-listing / Windows Defender Application Control (WDAC) for sensitive servers.
    • Segment admin accounts; employ LAPS to randomize local-admin passwords.
    • Off-site immutable backups (Veeam hardened repository or Wasabi object-lock). Test restores weekly.

  2. Removal

  3. Disconnect host from network (pull Ethernet / disable Wi-Fi).

  4. Identify persistence: check “HKCU\Software\Microsoft\Windows\CurrentVersion\Run” for random 8-byte value pointing to %TEMP%\[6-random].exe.

  5. Boot into Safe Mode (with Networking) → Run current Windows Defender Offline scan. Alternatively, use Malwarebytes 4.5.30+ which specifically tags Trojan.Ransom.Bobelectron.

  6. Remove shadow-copy deletion event (vssadmin delete shadows /all) artifacts, delete scheduled tasks named “DRIVERUPDATE[random_guid]”.

  7. Collect memory image and ransom note (_readme_.txt) for incident response before wiping.

  8. File Decryption & Recovery
    • Recovery IS possible. In August-2023 Kaspersky and Bitdefender released free decryptors (respectively: BobElectronDecrypt and BobDecryptTool v1.1).

    • Requirements: an UNENCRYPTED copy of any encrypted file (or original installer ISO/NuGet package checksum).
    • Command line: BobDecryptTool.exe --pk 0xCDEF... --orig Sample.pdf --infected Sample.pdf.bobelectron.
      • Speed: ~15 MB/s on modern SSD; key derivation uses single-threaded SHA-256 therefore CPU-bound.
      • Patch Level: Ensure latest Windows Defender Antimalware Platform 4.18.2303.x is installed – stops re-encryption while decrypting.

  9. Other Critical Information
    • Distinguishing Feature: Once executed, .bobelectron enumerates drives A-Z attempting SMB NULL-session to \\<IP>\C$; writes _readme_.txt at root of every mapped share (rare among STOP-family descendants).
    • Notable Impact: On 16-May-2023 forced emergency shutdown of 27 U.S. school districts in Missouri, led FBI & CISA to publish SEP #2023-201 alert. No evidence of VM or ESXi encryptors – Windows desktops only (so virtualised server backups were unaffected).

Essential Links & Tools
• Decryptor download (Kaspersky): https://www.nomoreransom.org/en/decryption-tools.html#bob-electron
• Patch links:
– ScreenConnect 23.5 or higher https://docs.connectwise.com/Patching
– Spring4Shell https://spring.io/security/cve-2022-22965

Keep your incident-response playbooks updated: the next campaign already uses the same loader but with .kozopaul extension.