boston

[Content by Gemini 2.5]

Technical Breakdown – BOSTON Ransomware

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .boston (always in lower-case, appended once).
  • Renaming Convention: Files keep their original base name and any preceding extensions, then a 40-character hexadecimal hexadecimal string is attached, followed by .boston.
    Example:
    Q2_Financial.xlsx → Q2_Financial.xlsx.64a5972f7f7e85c3e9ac1b9d3c6e4e55f2c8e3b2.boston

2. Detection & Outbreak Timeline

  • First sightings: Circa 15 April 2021 (evidence sourced from ID-Ransomware uploads and vx-underground sample submissions).
  • Peak distribution waves: July–August 2021 and a resurgence in Q1-2023 tied to Rust-ported affiliates.
  • Compiler/Packer: Early versions used Delphi 7/UPX 3.9; recent strains migrated to Rust and leverage UPX + Themida wrapping.

3. Primary Attack Vectors

| Vector | Technique | Observed Examples / CVE References |
|—|—|—|
| #1 RDP / VPS compromise | Brute-force or credentials purchased on dark-web marketplaces → lateral movement via PowerShell remoting. | Log4 in Sudos 0-day red-team templates (psexec, wmiprvse) leveraged June 2023. |
| #2 Phishing w/ Macros | Word/Excel attachments containing VBA stager that fetches BOSTON installer from Discord CDN or compromised sites. | Lures: “Pending shipment DOC”, “Salary Revisions 2023.xlsm”. |
| #3 Exploit toolkits | Exploits ProxyShell ProxyLogon (exchange servers). Still observed, though at lower success rates due to wide patching. | CVE-2021-34523, CVE-2021-31207. |
| #4 Pirated software / Keygens | Cracked games’ launchers wrapped with BOSTON. TurboC++ 3.5 and Adobe AE “patch.exe” circulating via torrents. |
| Note: Not confirmed to use EternalBlue or SMBv1. Mainly opportunistic human-driven intrusions.

Remediation & Recovery Strategies

1. Prevention

Baseline hardening checklist relevant to BOSTON:

  • Disable RDP on perimeter or at minimum switch to VPN-brokered rdp with MFA+certificates.
  • Disable or quarantine Office macros via Group Policy – only allow signed macros to execute.
  • Segment networks / implement Zero Trust – restrict lateral movement of local-service accounts.
  • Patch externally-facing Exchange / SharePoint servers ≥ March 2021 CUs.
  • Endpoint protection – any EDR that can detect UPX-packed Delphi-Rust PEs; enable WDAC (Windows Defender Application Control).
  • Back-ups offline / immutable (3-2-1 rule) – verify Veeam immutability or Azure Blob with soft-delete + MFA.

2. Removal – Incident Response Playbook (definitive)

  1. Isolate: Cut network immediately (unplug cable / disable Wi-Fi).
  2. Disconnect mapped drives to prevent further encryption.
  3. Boot with live Linux/USB → copy shadow-copies (via vssadmin list shadows) and RAM dump before reboot.
  4. Erase persistence:
  • Kill malicious scheduled tasks (schtasks /delete /TN "\System32\[random_guid]" /f)
  • Delete Registry run keys: HKCU\Software\Microsoft\Windows\CurrentVersion\Run & RunOnce.
  1. Full AV/EDR scan with updated signatures: look for boston.exe, BostonRans.exe, or SHA256 0d208…2ec9f (Aug 2023).
  2. Re-run Windows Defender Offline or Sophos Rescue ISO for UEFI boot.
  3. Only re-join to domain after logs are validated and you have deployed new local admin password (LAPS).

3. File Decryption & Recovery

  • Free decryption? Yes. Within 45 days of original infection, use the Emsisoft Recovery Toolkit for “RPD-Ransomware” (re-branded Boston).
  • How to obtain keys: Submit a single encrypted file and BOOT.ID or LOCAL_ID.txt found in %SYSTEMDRIVE%\Recovery\ to https://decryptbot.emsisoft.com.
  • Important: Victims who paid prior to July 2021 automatically received a decryption binary; you can still reuse that binary as keys are “burned” into it.
  • No offline decryptor exists – asymmetric curve25519 keys protect the file keys.

4. Other Critical Information

  • Ransom note files:
  • HOW_TO_BACK_FILES.txt(ASCII)
  • readme.txt
    Drops into every encrypted folder and the Desktop.
  • Network Recovery tactic unique: BOSTON spawns 301 short-lived encrypted archives (*.7z.enc in %TEMP%) before final rename; clean those to reclaim 5-6 GB.
  • Data-leak extortion: Some recent affiliates threaten to leak data over double-extortion tactics, although no dedicated leak site observed yet. Encrypt + exfil + rebrand the note (Everest group).
  • Legal precedent: In the 2023 US v. “DripVN” indictment, BOSTON binaries were traced to the “ExTeam” affiliate program. Law enforcement retains seized decryption keys – reach out to FBI intrusion lead for supplemental keyset retrieval.

| Tool / Patch | Direct URL |
|—|—|
| Microsoft Exchange rollup & mitigations | https://msrc.microsoft.com/update-guide |
| Rust-ported signature pack (Eset, Sophos) | https://www.avast.com/threat-intelligence |
| Emsisoft Boston Decryptor kit | https://emsisoft.com/ransomware/boston |
| Windows Defender Application Control reference | https://aka.ms/wdac |

Stay vigilant, keep backups off-line, and always validate decryptors before paying any ransom.