RANSOMWARE BRIEFING – File Extension “.dec”
Linking observed activity to the GlobeImposter 2.0 (a.k.a. “Fake Globe / NCrypt”) family
Technical Breakdown
1. File Extension & Renaming Patterns
• Confirmation of File Extension: all encrypted files are appended with the over-write extension “.dec” (without an additional dot; e.g., report.xlsx → report.xlsx.dec).
• Renaming Convention: GlobeImposter 2.0 does not pre-pend any e-mail or ID strings; original file name stays intact, only the extra “.dec” is appended. A plain-text ransom note (HOW_TO_RECOVER_FILES.txt or Read___ME.html) is dropped into every folder and on the desktop.
2. Detection & Outbreak Timeline
• Approximate Start Date/Period: first large-scale sightings of “.dec” GlobeImposter 2.0 campaigns recorded late July-August 2021, with steady waves continuing quarterly through 2022-2023 when affiliates rebranded the same builder. As of mid-2024 the TTPs remain virtually unchanged.
3. Primary Attack Vectors
• Propagation Mechanisms
– RDP brute-force / credential stuffing (port 3389 exposed to the internet and thinly-secured jump hosts).
– SonicWall SMA & Citrix ADC (NetScaler) exploits (CVE-2020-5135, CVE-2019-19781, CVE-2020-3452).
– e-mail phishing with ISO / password-protected ZIP attachments containing droppers.
– Living-off-the-land execution: WMIC, CertUtil, PowerShell, BITSAdmin used for lateral movement & payload staging.
– SMB abuse only occurs after domain elevation; the variant itself does not exploit EternalBlue, but still disables the firewall and clears event logs.
Remediation & Recovery Strategies
1. Prevention
- Completely block TCP/3389 inbound from the internet; enforce VPN-only RDP (with MFA).
- Patch SonicWall, Citrix, Fortinet and any edge appliances quarterly (critical CVE list above).
- E-mail gateway: strip ISO, IMG, VHD, 7-Zip, and password-protected archives by default.
- Enforce AppLocker / WDAC to prevent executables launching from
%APPDATA%,%TEMP%,\Public\. - Maintain tiered backups: on an immutable / air-gapped location, 3-2-1 rule, daily snapshots with separate credentials.
2. Removal (Windows focus)
- Isolate infected systems immediately; pull network cables or isolate VLAN.
- Collect an image of at least one host for FBI/team forensics before any remediation.
- Boot into Safe Mode with Networking; run Microsoft Defender Offline Scan or Sophos Bootable Rescue.
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Inspect persistent locations:
•HKCU\Software\Microsoft\Windows\CurrentVersion\Run
• Scheduled Tasks created with names masquerading as Windows Update (svchostUpd, etc.).
• Startup folders%AppData%\Microsoft\Windows\Start Menu\Programs\Startup. -
Delete residual artifacts: drops usually are named
fname.bat,winserv.exe,winupdate.exein%AppData%. - Reset all local & cached domain credentials to eliminate residual access; rotate KRBTGT twice.
3. File Decryption & Recovery
• Recovery Feasibility: NO freely available GlobeImposter 2.0 decryptor exists for files marked “.dec”. Decryption is only possible if:
– a) compromised hosts obtained the victimprivatekey prior to malware removal, OR
– b) an affiliate screw-up leads to a public key dump (extremely rare).
• Essential Tools & Patches
– Prevention: Windows security rollup April 2023 and later (includes RDP CredSSP hardening).
– Detection/Osquery: Elastic Kibana “winlogbeat-gimposter-detection” rules by SIGMA tag.
– Back-up / Immutable Storage: Veeam Hardened Linux Repository or Wasabi Object-Lock buckets.
4. Other Critical Information
• GlobeImposter 2.0 is fully data-extortion capable: it exfiltrates to Mega or multcloud[.]com via Rclone set with —multi-thread-streams 4. Expect a double-extortion leak-site entry within 48 h post-infection.
• Post-encryption obfuscation: it wipes Volume Shadow Copies with vssadmin delete shadows /all /quiet, clears Windows Event Logs with wevtutil cl System, and disables crash-dumps.
• Notable effects: in H2-2022 it hit at least 25 U.S. municipal governments and two national hospitals in Brazil. Sophisticated affiliates now funnel access via IAB (Initial Access Brokers) leveraging starting prices on Genesis Market ($160-$500 for valid RDP creds).