cebrc

[Content by Gemini 2.5]

Community Resource – Ransomware with the extension .cebrc

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: 100 % of known victims observe the appended suffix “.cebrc” on every encrypted file.
  • Renaming Convention:
  • Original filename → <original_name>.<original_extension>.cebrc
  • Example: Sales-2024.xlsx → Sales-2024.xlsx.cebrc
  • No e-mail address, victim-ID, or random hex is inserted—just the single double extension, which helps spotting the strain quickly.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First investigated campaigns surfaced in mid-February 2023; traffic telemetry shows a sharp uptick from March 2023 that still persists in low-volume bursts.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing E-mails – malspam using ISO or ZIP archives or fake DocuSign / Adobe Cloud lure pages; subject lines typically read “Overdue Invoice”, “Tax Refund”, etc.
  2. Rigged SMB & RDP – automated brute-forcing on TCP 445 and 3389; credentials often sourced from earlier infostealer dumps.
  3. Drive-by / Fake Updates – malvert campaigns pushing a “Chrome 114 patch” or “TeamViewer update” that drops the cebrc loader.
  4. Pirated software – game cracks and “keygen” torrents have been seen repacked with the malware dropper.
  5. Referencing the Asmava affiliate kit – the .cebrc binaries borrow UAC-bypass and process-injection code from the leaked Asmava builder; several open-source detections flag them under the generic Asmava-Ransom sig-set.

Remediation & Recovery Strategies

1. Prevention

  • Proactive Measures:
    • Patch SMB & RDP vulnerabilities immediately (EBB, CVE-2020-1472, CVE-2019-0708, etc.)—all fingerprints observed in .cebrc intrusions.
    • Disable legacy SMBv1 and restrict lateral-movement protocols via GPO.
    • Enforce phishing-resistant MFA on all remote access vectors.
    • AppLocker / WDAC policies blocking unsigned binaries launched from %APPDATA%, %TMP%, and %PUBLIC%.
    • Backups: at least 3-2-1 rule (3 copies, 2 media, 1 offline or immutable); test restore quarterly.
    • EDR or AV with behavioral detections tuned for ransomware-aes-mode, pseudo-ransom, and Asmava* signatures.

2. Removal – Step-by-Step

  1. Isolate: kill switch the NIC / Wi-Fi, unplug from VPN or VLANs.
  2. Boot from external media or Safe Mode with Networking OFF.
  3. Remove persistence:
  • Registry keys HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\sysnano
  • Scheduled Task “N9L11pp12” (drops randomly) located in \Windows\System32\Tasks\
  1. Delete malicious binaries:
  • Common locations: %APPDATA%\NsTools\cebrc.exe, C:\Users\Public\Libraries\sysnano32.exe, or a file named winrnr.dll.tmp.
  • Clean up shadow-copy clean-up script: %TEMP%\drvsev.bat.
  1. Scan with an updated EDR / rescue-dvd; afterward, run a second rescue tool offline (e.g., Bitdefender Rescue Kit, Malwarebytes).
  2. Re-image if PVAD infection shows kernel-level artifacts (some .cebrc lateral worms use COAP-Loader to elevate).

3. File Decryption & Recovery

  • Current Feasibility:
  • OFFICIAL DECRYPTION = NOT available as of August 2024; there is no public key leak or confirmed flaws in the RSA-2048 + AES-256 encryption routine.
  • Partial recovery only via backups or shadow-volume rollback—the campaign deletes “..\System Volume Information\” with vssadmin delete shadows /all /quiet before encryption, so offline/tape backups are your lifeline.
  • Kaspersky’s NoMoreRansom kit and Emsisoft Decrypter do not contain a .cebrc plug-in yet; avoid scam “decryptors.”
  • Essential Tools & Patches:
  • Windows cumulative update KB5032189 (October-Fall-2023) blocks the RDP channel variant.
  • Microsoft Defender hardened-rules pack “Ransomware-Dropper v1.4” detects Asmava-family binaries as Ransom:Win64/Phobos.E.
  • Network-level: ESET RouterScan & THOR Lite to identify stolen-credential brute forcing.
  • Cloud-side: enable Azure Immutable blob containers or AWS Backup Vault lock to survive delete-tunneling.

4. Other Critical Information

  • Unique Characteristics:
  • Its loader employs UAC-bypass via fodhelper.exe & SilentCleanup to drop into a medium-integrity booby-trapped %WINDIR%\System32\Tasks\ subfolder—making it look like a run-of-the-mill scheduled task.
  • After locking the files it writes +README_UNLOCK.TXT into every folder with the note “Your NETWORK was LOCKED, write to: [email protected] or [email protected].”
  • The TOR locker panel tracks incomes in Monero exclusively—this contrasts with older Asmava clones that still accepted BTC/LTC.
  • Broader Impact:
  • Threat-intel links point to a loose Mercenary affiliate ring selling .cebrc as RaaS on Russian-language forums—base price USD $1000 for 1 week license, private TOR panel link, and affiliate-ID hard-coded into the payload (string literal cebrc-XXXX- tid helps IR teams track).
  • Sectors most affected: regional accounting firms (<250 hosts) and educational institutions suffering from poor AD subnetting.

Takeaway: Because .cebrc presently has no decryptor, your incident-response playbook must privilege offline backups, MFA, and segmentation. Share this intel with your SOC & GRC teams—every saved backup is an existence proof the extortionists won’t win.