_nemty_btkid9h_

[Content by Gemini 2.5]

Ransomware Resource – _nemty_btkid9h_ Variant

Technical Breakdown

  1. File Extension & Renaming Patterns
    • Confirmation of File Extension: The ransomware appends nemtybtkid9h to every encrypted file (e.g., document.pdf→document.pdf._nemty_btkid9h_).
    • Renaming Convention: ..nemtybtkid9h (case insensitive; no prefix, no random hex block). The desktop wallpaper and each directory also receive a ransom note named NEMTY-DECRYPT.txt.

  2. Detection & Outbreak Timeline
    • Approximate Start: October 2019.
    • Spike Period: Campaigns crescendoed between late-Oct 2019 and early-Mar 2020, with occasional resurgences using fresh affiliate builds through 2021. Public submissions in VirusTotal began 26 Oct 2019.

  3. Primary Attack Vectors
    • RDP Brute-Force & Credential-Stuffing – Most common entryway. Default/weak credentials or leaked log-ins scanned on TCP 3389.
    • Malspam & Phishing – ZIP/ISO attachments inside messages pretending to be invoices, invoices-overdue lures. Payloads include IcedID or Trickbot that drop Nemty.
    • Exploitation of Public-Facing Services –
    – Unpatched 1-day vulnerabilities in Oracle WebLogic (CVE-2017-10271) and Windows servers via SMB弱点 (not WannaCry’s EternalBlue, but weak SMB shares).
    – Exploit kits such as RIG and Fallout in early waves.
    • Affiliate/As-a-Service Distribution – After November 2019, Nemty transitioned to a RaaS program, letting different groups supply the initial bot.

Remediation & Recovery Strategies

  1. Prevention
    ✔ Patch RDP issues: disable on edge, enforce NLA + MFA, use VPN with 2FA before 3389 is reachable.
    ✔ Strict password policy → min. 14-char long, no shared credentials.
    ✔ Segment networks; lock high-value servers behind subnet ACLs/fws.
    ✔ Email filtering: block wildcard executables (.exe, .js, .wsf) and ISO/IMG/ZIP content from external senders.
    ✔ Apply OS & application patches monthly; prioritize CVE-2017-10271, BlueKeep (CVE-2019-0708), and SMBv1 shutdown.
    ✔ Configure reputable EDR or NGAV to monitor for LOLBins (PowerShell, WMI, rundll32).
    ✔ Back-ups: daily 3-2-1 strategy – three copies, two media, one off-line/Cloud w/ immutability.

  2. Removal (If you’re already hit)

  3. Isolate & Contain – Power-off the ransom instance, disable NIC, disconnect all mapped or Cloud folders.

  4. Forensic Triage – Copy (dd or FTK imager) a forensic disk or memory image before cleaning; keeps legal evidence.

  5. Boot from Clean OS – Windows PE/WinRE, bootable AV, or Bitdefender Rescue CD.

  6. Scan & Clean
    – Full-scan offline using updated engine (Windows Defender, Kaspersky, ESET); create a dedicated “cleanup” admin account.
    – Disable scheduled tasks and services matching RandomName.exe / rundll32 payloads in C:\ProgramData or %TEMP%.
    – Rename/revoke any compromised service accounts.

  7. Verify Network Hygiene – check firewall logs for persistent RDP brute-force IPs, block.

  8. Rebuild – Nuke-and-pave high-risk PCs if worm residue is suspected (PDB paths show build_20191025).

  9. File Decryption & Recovery
    • Official Public Decryptors? NO. As of today there is no universal decryptor for the .nemtybtkid9h_ branch. RSA-2048 + AES-128 crypto works offline; private keys hidden.
    • Potential Work-Arounds:
    ─ Back-ups / Shadow-Copies (Nemty deleted them with vssadmin delete shadows). If offline images exist, rebuild and copy back.
    ─ File-recovery via reputable data-carving tools (PhotoRec, R-Photo) from unencrypted shadow or sanitized SSDs/HDDs if only quick format by attacker.
    • Idle Hope: Less than 3% improvement rate for Nemty keys from Law-Enforcement seizures; no matching “NemtyRevenge” private key leak yet.
    • Patch & Tool Summary:
    – KB4499175 (BlueKeep), KB4534273 (Jan 2020 cumulative).
    – MS17-010 (even though Nemty doesn’t worm on MS17-010, patching prevents co-infection).
    – CrowdStrike Falcon / SentinelOne current agents detect as Ransom.Win32.NEMTY.

  10. Additional Critical Notes
    • Persistence Techniques: Creates service SbieSvcNew disguised as Sandboxie.
    • Lateral Movement: Uses leaked Mimikatz-style modules; dumps LSASS memory (Mimikatz_log.txt).
    • Ransom Pricing: Adds geographic check with public IP; countries RU, BY, KZ, UA, TJ exempt (early builds avoid victims).
    • Double Extortion: Actor uploads 5 % of victim data to Tor blog “Nemty News” to pressure payment → treat breaches as PII/PHI incidents.
    • Indicators of Compromise (IoCs):
    – Registry keys HKCU\Software\NemtyProject
    – Hard-coded mutex {1D6DD08D-A758-F77F-0875-7EB29B7211FC}.

Use this cheat-sheet as a living document: rotate EDR feeds, patch aggressively, test backups quarterly.