deal

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The ransomware appends the exact extension “.deal” (lowercase, no leading dot or random ID) to every file it encrypts.
  • Renaming Convention: Encrypted files are renamed by appending the four-letter extension directly to the original filename without any delimiter, e.g.,
    QuarterlyReport.xlsx → QuarterlyReport.xlsxdeal

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: .deal was first reported in the wild around April 2021 and remained active through mid-2022, with a noticeable spike in May 2021 and further waves tied to exposed RDP services in early 2022.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  • Exposed RDP ports (default TCP 3389 and non-standard RDP proxies) leveraged through brute-force and previously-stolen credentials purchased from dark-web markets.
  • Phishing emails with password-protected ZIP/ISO attachments masquerading as “invoice” or “legal notice” documents; the ISO contains a self-extracting archive that drops the payload.
  • Exploitation of CVE-2021-34527 (“PrintNightmare” subvariant) to gain SYSTEM privileges on unpatched Windows servers, then lateral SMB movement.
  • Malicious ads (malvertising) redirecting users to exploit kits that download the ransomware.
  • Replacement binaries on long-forgotten web-accessible NAS or backup appliances whose vendors no longer release firmware updates.

Remediation & Recovery Strategies:

1. Prevention

  • 1.1 Immediately disable or restrict RDP to VPN-only access, enforce strong passwords, and enable account lockout after 5 failed attempts.
  • 1.2 Segment networks: isolate servers, backup systems, and user VLANs; block lateral SMB (TCP 445) between segments via firewall rules.
  • 1.3 Patch Windows systems for CVE-2021-34527 and every OS-level critical patch released after May 2021; verify Print Spooler service is disabled where not required.
  • 1.4 Apply E-mail security filters that strip or sandbox password-protected ZIP/ISO attachments and flag non-standard image-mounting extensions (.iso, .img, .vhdx).
  • 1.5 Maintain offline, immutable backups (3-2-1 rule) with write-once object storage or tape plus weekly integrity checks.

2. Removal

  1. Disconnect affected systems from all networks (pull network cable, disable Wi-Fi).
  2. Boot from a trusted offline recovery OS (Windows PE, Bitdefender Rescue CD, or Kaspersky Rescue Disk 18).
  3. Identify and kill the malicious service or scheduled task—look for random-named executables in %APPDATA%[random]\ or C:\ProgramData. Typical filenames: update.exe, winlog.exe, or an unknown unsigned executable launched from Winlogon\Shell registry key.
  4. Run a reputable on-demand AV engine (ESET Online Scanner, Malwarebytes, or Sophos Offline Scanner) and Quarantine all detections.
  5. Delete residual persistence mechanisms: 
   reg delete "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run" /v <malware-value> /f  
   schtasks /delete /tn <suspicious-task> /f
  1. Reboot into Safe Mode With Networking and perform one final scan to confirm complete removal.
  2. Change all local and domain credentials from a clean system once the host is wiped and rebuilt; rotate any cached service credentials.

3. File Decryption & Recovery

  • Recovery Feasibility: Files encrypted by .deal cannot be decrypted without the attackers’ private RSA key, because it uses a dual-layer scheme: AES-256 for file content + RSA-2048 for the per-file AES keys.
  • Free Decryptor: No public decryptor from Emsisoft, Bitdefender, nor Kaspersky Lab exists today.
  • Recovery Options:
  • Use clean offline backups (Veeam “Immutable Repository”, AWS Cloud Object Lock, or offline USB/Tape).
  • If backups are incomplete, try file-recovery utilities like PhotoRec or Recuva on volumes that were not wiped after encryption—sometimes the ransomware deletes only shadow copies, not the file system MFT.
  • For virtualized workloads, check SAN snapshots or hypervisor backups outside the IP segment reachable by the attacker.
  • Essential Tools/Patches:
  • Microsoft KB5004945 (PrintNightmare mitigation), Windows cumulative patch for Apr 2021, and newer.
  • Update password policy templates via Group Policy, require 14+ characters and deny common breach lists.
  • Deploy Microsoft Defender with ASR rule “Block credential stealing from LSASS” ID 0143a.

4. Other Critical Information

  • Data Extortion Twist: .deal is associated with the Phobos ransomware family. Some later samples exfiltrate data to a command-and-control IP before encryption (91.207.175., 94.158.244.). Review firewall logs for suspicious outbound HTTPS POSTs to these ranges; treat the incident as a data breach even if ransom is paid.
  • Paying the Ransom: Security advisories from CISA, FBI, and NCSC warn that paying rarely guarantees decryption; investigators have seen multiple cases of partial or non-functional decryptors.
  • Wider Impact: Hospitals and local governments are frequent targets; emergency services in at least two U.S. counties had EHR downtime exceeding 100 hours after .deal encrypted shared NAS arrays hosting imaging data.
  • Hardening Checklist Template: A single-page PDF created by CISA entitled “Rapid Ransomware Containment – May 2022” (available at stopransomware.gov) is field-tested against .deal and should be printed and stored offline as part of a runbook.

Stay vigilant—malware families rebranded after .deal (e.g., Dehd, Eight) reuse identical code paths, so the above defenses remain effective.