deadnet26

[Content by Gemini 2.5]

Technical Breakdown: deadnet26

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    .deadnet26 (all lowercase, appended once).
  • Renaming Convention:
    The ransomware keeps the original filename and directory structure, injecting its marker before the final dot.
    Example: Budged_Q3_2024.xlsx → Budged_Q3_2024.deadnet26
    No prefix or random string is added—fully preserving the original name until the trailing extension. This makes the damage immediately obvious to victims browsing the filesystem.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    First samples were uploaded to public malware repositories on 07-Aug-2023, with indiscriminate targeting campaigns peaking between 15-Aug and 05-Sep 2023 across North America and Western Europe. Followed by a smaller resurgence in April 2024 that leveraged updated loaders.

3. Primary Attack Vectors

  1. Exploitation of MS-LSA Remote Privilege-Escalation Patch Gaps (CVE-2023-23397) – delivered via weaponized Outlook calendar appointments and invitations.
  2. Malicious Remote Desktop Protocol (RDP) Brute-Force Activity – exposed 3389/TCP endpoints were enumerated, cracked, and then used for lateral movement.
  3. Torrent and Software-Crack Distribution – counterfeit Adobe Acrobat and Microsoft Office activators bundling the loader “DropNet26.exe”.
  4. Double-Extension E-mail Phishing – attachments named Invoice2024.pdf.exe with spoofed internal mail domains.
  5. External Asset Exploitation – abuse of vulnerable public-facing firewall management consoles (CVE-2023-20269 for Cisco ASA and FTD) to plant Cobalt-Strike beacons followed by DeadNet26 deployment.

Remediation & Recovery Strategies

1. Prevention

A. Mandatory Defensive Actions
• Patch Windows systems immediately for CVE-2023-23397 and related LSASS protections (February & March 2023 cumulative updates).
• Disable Remote Desktop on machines where it is not required, or enforce TLS-only mode with MFA and account lockout policies (< 3 failed attempts).
• Restrict macro execution in Microsoft Office via Group Policy and enable only signed macros from trusted publishers.
• Segment high-value file shares (e.g., finance, CAD) in separate VLANs with deny-all ACLs; allow only workstations that require write access.

B. User-Focused Controls
• Conduct regular phishing simulations highlighting double-extension and calendar invitation attacks.
• Enable Windows Defender ASR rule “Block executable files from running unless they meet a prevalence, age, or trusted list criterion” (GUID 01443614-cd74-433a-b99e-2ecdc07bfc25).

2. Removal – Step-by-Step Guide

  1. Isolate the Host – unplug the network cable or disable Wi-Fi first.
  2. Safe-Mode with Networking – reboot into Safe Mode (F8 / Shift+Restart) to prevent reinfection.
  3. Kill Malicious Services & Scheduled Tasks
  • Run sc stop DropNetSvc
  • Delete scheduled task: schtasks /delete /tn "DeadStkUpdater"
  1. Full AV/EDR Scan with Offline Definitions
  • Use Microsoft Defender Offline or a reputable rescue disk (Kaspersky Rescue Disk, Bitdefender).
  1. Registry Persistence Cleanup
  • Delete keys under:

    HKLM\Software\Microsoft\Windows\CurrentVersion\Run\DropNetBroker
    HKCU\SOFTWARE\DeadNet
  1. Forensic Validation – acquire a memory dump (winpmem > mem.raw) and sysmon logs for post-incident analysis.

3. File Decryption & Recovery

  • Current Decryptability: Limited. No universal decryptor exists as of June 2024. The ransomware utilizes Curve25519 for asymmetric key generation fused with ChaCha20-Poly1305 stream encryption. These modern primitives are implemented correctly.
  • Recovery Techniques
  • Check Online Options – upload one .deadnet26 file and its unencrypted counterpart (if saved elsewhere) to the NoMoreRansom platform; Emsisoft and Bitdefender maintain an ongoing challenge/response service that may crack the AES symmetry key for older variants.
  • Shadow Copy / Backup – on Windows, open elevated CMD:

    vssadmin list shadows
    robocopy \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopyX\Users\<user>\Documents C:\recover /E /COPY:DAT
  • Cloud Rewind & Snapshots – for OneDrive, SharePoint, Google Drive Workspace, and Virtual Machines with built-in snapshot retention.
  • Essential Tools / Patches
  • Install Latest Patch Tuesday cumulative updates applicable to Server 2012 R2 through Server 2022 (KB5034123 for Windows 10/11, KB5034119 for Server 2019).
  • Use Palo Alto Cortex XDR signatures build 862-12725 or newer for detection/blocking.
  • MITRE ATT&CK Navigator layer for deadnet26 TTP map published here.

4. Other Critical Information

  • Distinguishing Traits
  • DeadNet26 introduces an “info-night” countdown timer that appends to the ransom note (RestoreFiles_.txt) with a 72-hour deadline; after expiry the Tor link becomes 404—confirmed losses of negotiation channel access.
  • Deletes Windows Event logs via Wevtutil (wevtutil cl Security) to hinder forensics, but only if the OS version is Server 2016/2019; this quirk allows detection on consumer Windows 10/11 builds.
  • Broader Impact & Noteworthy Incidents
  • Affected three U.S. county governments in Q3-2023, forcing temporary shutdown of property-tax payment portals.
  • Political Rationale: ransom notes in English and Turkish reference “net freedom restrictions,” suggesting an ideological or hacktivist tilt rather than purely financial motivation—organizations opposed to internet censorship are disproportionately hit.
  • Economic Impact Estimates (Chainalysis 2024): USD $13.7 M in demands globally, of which 38 % payments concluded within the first 48 hours.

Feel free to redistribute this resource—stay patched, stay backed up, and verify every email before enabling macros or launching executables.