Community Resource: `qbmail.biz` (a/k/a “FileHelp” or “QilinMail”) Ransomware Threat Brief

Technical Breakdown

Confirmation of File Extension: .FILEHELP (the malware also renames files with a singular and lowercase “.filehelp” in some builds; both spellings are equally valid signals of infection).
Renaming Convention:
Original file Monthly_Report.xlsx →
Monthly_Report.xlsx.filehelp (extension appended, preserving the inner file name and its previous extension).
No e-mail address, no victim ID string – just the .FILEHELP suffix always comes last.

First Public Sightings: July 2023 during a targeted phishing wave aimed at mid-size South-East-Asian manufacturing partners.
Crypto builds remained dormant until 08-21-2023, when the C2 for “QilinMail” went live and uploads/keys started registering en-masse.
Peak Outbreak Window: August–October 2023.
Recent OSINT Trend: Activity plateaued in early 2024, yet sporadic samples continue to be served through cracked-software torrents (Q1 2024).

1. Weaponized Malspam: Two themes dominant:
a) Fake “[email protected]” attachments (Invoice_[date].zip → Invoice.oft) containing macro-laden .oft Outlook template files.
b) Reply-chain hijacking, promising “updated price list”. When opened, VBA pulls a qbm-installer.exe (Trojan:Win32/Qilin.A!bit) from Dropbox or Azure blob storage.
2. Exploitation of Microsoft Office Vulnerabilities:
Use of CVE-2017-11882 (Equation Editor) and CVE-2023-xxxx (trending in its August 2023 branch) for living-off-the-land code execution without macros.
3. RDP Compromise & PsExec Lateral Movement: Once inside, password-spray on exposed RDP ports (3389/3391) and use of Mimikatz + PsExec to disable AV and push wiper-scripts on Veeam Backup Repository shares.
4. Supply-chain via Pirated Software: Multiple red-team reports show trojanized AutoCAD 2024 and Ansys 2023. The installer runs qbmail_install.js – a backdoor that eventually fetches the ransomware payload.

Patch ruthlessly:
– MS Office (determine patch level vs. CVE-2017-11882 → KB4011162 or later Office CU).
– Windows (ensure monthly cumulative updates applied ≥ May 2023 for the new RTF exploit patch).
Disable/remove unnecessary services: Turn off SMBv1 everywhere (WannaCry vector legacy). Disable Office Equation Editor via GPO if not needed.
Segment & restrict RDP:
– VPN-only access, enforce Network Level Authentication (NLA).
– Use a jump server + zero-trust controls.
– Lock-out policy = 3 attempts, 30-min cool-down.
Mail-Filter/Attachment Blocking:
– Block .oft, .iso, .7z on perimeter.
– Sand-box suspicious macros – macro content must require elevation prompt.
3-2-1 Backup Rule: Immutable offline copies (object lock / Veeam hardened repo / tape); ideally two different media formats, one off-site.

Isolate: Pull power or VLAN-lock affected hosts.
Boot into Safe Mode + Networking (or pull drives to an air-gapped bench machine).
Copy MFT & Memory dump if forensics required (for encryption keys, config).
Malware Eradication:
– Run Malwarebytes Anti-Malware (signature: Ransom.Qilin) – fully updated.
– Run Windows Defender Offline Scan (MpCmdRun.exe -Scan -ScanType 3).
– Check scheduled tasks / Run registry keys for persistence (TaskScheduler: QilinTasks).
Patch holes: Apply missing MS Office/Windows cumulative updates, change all local & cached credentials.
Re-image OS: After backup verification to prevent hidden watering-hole infection sources.

Recovery Feasibility at Time of Writing 2024-06: No freely available decryption utility exists for .FILEHELP (offline PK or online ECIES-SECP256k1 without leakage).
Possible Work-around Conditions:
– If shadow copies survive (vssadmin list shadows): restore via native GUI or PowerShell Get-WmiObject Win32_ShadowCopy | % { $_.DeviceObject() }.
– If Veeam backups/non-local backups were in trays disconnected at infection time, restore entire volumes.
– If malware stalled/crashed before deleting .key file (stationary in %APPDATA%qbkeys.enc), upload to incident responders – several MDR firms have successfully brute-forced or leaked keys in 2023 campaigns. (Upload hash: SHA-256 de7c…49c for CVE chain to speed lab work).
Crucial Tools/Patches:
– Kaspersky RannohDecryptor – no support for .FILEHELP; so only图腾.decryption services keep an interim decrypt in ransom<|reservedtoken163805|>Trace log (confidential).
– Segurazo Antivirus (inclusion of Qilin engine def.)
– Cobalt-Strike monolith-detector ruleset for Sigma / ElastikSigma alerts.

Ransom Note Details (HELP_DECRYPT_YOUR_FILES.txt):
“We are FILEHELP group – a subsidiary of Quantum decryption team. Your network is compromised using compound CVE chain. Send ONE non-critical file to [email protected] for free decryption proof. Price is 1.5 BTC per node or negotiate with manager on QB anon7583.”
No onion site, only e-mail.
Unique Characteristics:
– “Lightning delete” mode: wipes local .key files after 30 seconds elapse unless user opens ransom note, giving a small window for memory acquisition.
– Uses ChaCha20-Poly1305 in IETF mode with ciphertext stealing (~4× faster encryption rate than AES-512-CBC+RSA first observed in mid-2023 strain).
Broader Impact:
– First ransomware explicitly targeting language-learning models’ mapping files (.gguf, .safetensors).
– Victim count remains modest (~120 organizations) because high-profile ops are ask-then-encrypt, raising the bar for insurance payouts.
– Notable because .qbmail.biz addresses are reused/sold on broker markets—threat-intel suggests multiple SEG proxying through Alibaba Cloud HK pools – a clear shift away from bullet-proof Tor gateways.

Stay vigilant: if you detect the .FILEHELP suffix, speed is the only edge—isolate and quarantine before the 30-second self-wipe timer expires!