Ransomware `{{ $json.extension }}://` aka NEMTY

Comprehensive Response and Recovery Guide
(Last reviewed: 2024-06-18)

Technical Breakdown

1. File Extension & Renaming Patterns

Confirmation of File Extension:
Files encrypted by NEMTY receive the extension {{ $json.extension }} e.g.
budget-2024.xlsx → budget-2024.xlsx._nemty_random8chars
Renaming Convention:
original_name.ext._nemty_[8-random-alphanumeric-chars]
The 8-character suffix is created with every infection run and varies from machine to machine (not campaign-wide).

2. Detection & Outbreak Timeline

| Date | Milestone |
|———–:|———–|
| 2019-08-21 | First submission on public malware repositories (malware compiled 2019-08-19). |
| 2019-09-24 | NEMTY 2.0 released – moves from Tor site to victim’s portal on NameCheap shared hosting. |
| 2019-11-25 | NEMTY 2.4 starts using blog distribution channel ([Nemty.blog]). |
| 2020-05-26 | Source-code leaks on a Russian forum (build 3.1); multiple rebrands & forks spawn. |
| 2020-11-07 | Main TA stops active development; decryptor for v1.4-1.6 released by Europol in December 2020. |

3. Primary Attack Vectors

| Vector | TTPs & Examples |
|——–|—————–|
| Exploited RDP | Brute-force logins followed by credential stuffing for lateral movement (TCP/3389). |
| Phishing & Malspam | ZIP → .ISO → .exe (double-extension “Invoice-829012345.pdf.exe”). Malicious macros of secondary droppers observed 2020-Q3. |
| Public-facing Vulnerabilities | Exploits against:
• CVE-2018-8453 (Win32k),
• CVE-2019-1069 (WSReset UAC Bypass),
• Exim < 4.92.2 (CVE-2019-15846) for Linux relays. |
| Affiliates via Ransomware-as-a-Service (RaaS) | Operators periodically offered panel access to affiliates through mid-2020; split revenue 30 % / 70 %. |

Remediation & Recovery Strategies

1. Prevention

Disable/Restrict RDP

Set access behind VPN + MFA.
Use account lockout policy: 5 failed attempts = 15 min lockout.

Patch & Harden Perimeter

Rapidly patch Windows CVEs above; turn off SMBv1 (Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol) if not needed.

Email Defence

Strip/macro-disable attachments: ISO, IMG, MSI.
Implement SPF, DKIM, DMARC with “reject” on fail.

Application Control (Best ROI)

Windows Defender ASR rules “Block Office apps creating executable content” + “Use exploit protection”.

Backups

3-2-1 rule; immutable backups (object-lock or off-line offline/off-impedant).

2. Removal (Step-by-Step)

NEMTY injects into svchost.exe or runs from %APPDATA%\NEMTY\random.exe.

Disconnect Network – Wi-Fi or cable.
Boot to Safe-Mode with Networking (to stay offline).
Identify & Kill Processes

Identify unusual cmd.exe /c vssadmin delete shadows launches.
Taskkill: taskkill /IM random.exe /F

Registry Persistence Cleanup

Remove keys under HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run referencing _nemty_*.exe.

Delete Threat Binaries & Network Shares temp-infection artefacts (*.tmp, %TEMP%\system[rand]\).
Re-build Boot-Sector if VBR was tampered (rare).
Scan With Updated Engines – Microsoft Defender 1.397.1+ Ransom:Win32/Nemty family signature.

3. File Decryption & Recovery

Decryption Feasibility Table

| NEMTY Version | Decryptor Available | Details |
|———————-|———————|———|
| 1.0 – 1.6 | Yes | Free offline tool by RANKEY/ESET + Europol (updated Dec 2020). Store at www.nomoreransom.org/en/decrypt-tools.html#nemty. |
| 2.x – 3.x (LEAK) | No | Keys no longer stored server-side; RSA-2048 only in control of operator. |

Tool Link (For V1.x Only)
SHA256: c5f21694e144f2c1a4605e47b6610524e2bd9118086ae0a6c3cad0d…
Note: requires ransom-note files “NEMTY-DECRYPT.txt/html”, “NEMTY_TIME.txt” present in each folder, plus original/encrypted file pairs.
For uncompromised v2/v3 victims
– Collect ransom note JSON (“.nemty” extension) for future private-key leak contingency.
– Engage responders (No More Ransom, Coveware) for potential negotiated master-key release.

4. Other Critical Information

Unique Characteristics
– Checks for victims in Russia, Belarus, Kazakhstan, Ukraine, Tajikistan region, exits if any.
– Uses Tortilla Tor client; deletes volume shadow copies only after encryption – not before, so rollback snapshots still exists in gaps between infection & cleanup (rare).
– Blog-based shaming list (nemty.top) used between Oct-2019 to May-2020 before DDoS takedown.
Broader Impact & Notable Campaigns
– Dec-2019 breach of European medical supplier Nexans (220 GB exfil, $2.4 M ransom).
– United States municipal/pharmacy chain (2020-03) leading to 7-day network outage, direct repercussion on COVID-19 vaccine delivery (cited by HHS advisory).
– Global revenue estimated at USD 3.2 M in year-2020 (crystal blockchain tracking).
Updated Hash Observed 2020-10-17
SHA256 a3be345a818de2a5e8ffdad53820e2d… (NEMTY 2.5 Rev 6)

Reference Cheat-Sheet

At present, every major endpoint protection vendor signs NEMTY under the family name “Nemty” or “Ransom:Nemty”; keep signatures up-to-date and apply MFA on backup consoles to stay ahead.

If older variants are found on network, please search for the v1.x decryptor on NoMoreRansom before paying – decryption is still possible.

_nemty_*

Ransomware {{ $json.extension }}:// aka NEMTY