Russian GRU Global Brute Force Attacks

Web Servers Systems Networks
Advisory ID:
July 2, 2021


The Russian General Staff Main Intelligence Directorate (GRU) 85th Main Special Service Center (GTsSS), military unit 26165, is reported to be conducting a Global anonymized Brute Force Campaign to Compromise Enterprise and Cloud Environments. This attack is discovered to be targeting government and foreign organizations using brute force access to penetrate government and private sector victim networks.

Description & Consequence

Malicious cyber actors use brute force techniques to discover valid credentials often through extensive login attempts, sometimes with previously leaked usernames and passwords or by guessing with variations of the most common passwords. While the brute force technique is not new, the GTsSS (85th Main Special Service Center) uniquely leveraged software containers to easily scale its brute force attempts. Once valid credentials were discovered, the GTsSS combined them with various publicly known vulnerabilities to gain further access into victim networks. This, along with various techniques allowed the actors to evade defenses and collect and exfiltrate various information in the networks, including mailboxes.

This brute force capability allows the 85th GTsSS actors to access protected data, including email, and identify valid account credentials. Those credentials may then be used for a variety of purposes, including initial access, persistence, privilege escalation, and defense evasion. Targets include government and military, defense contractors, energy companies, higher education, logistics companies, law firms, media companies, political consultants or political parties, and think tanks.


As with mitigations for other credential theft techniques, organizations can take the following measures to ensure strong access control:

  1. Use multi-factor authentication with strong factors and require regular authentication. Strong authentication factors are not guessable, so they would not be guessed during brute force attempts.
  2. Enable time-out and lock-out features whenever password authentication is needed. Time-out features should increase in duration with additional failed login attempts. Lock-out features should temporarily disable accounts after many consecutive failed attempts. This can force slower brute force attempts, making them infeasible.
  3. Some services can check passwords against common password dictionaries when users change passwords, denying many poor password choices before they are set. This makes brute-force password guessing far more difficult.
  4. For protocols that support human interaction, utilize captchas to hinder automated access attempts.
  5. Change all default credentials and disable protocols that use weak authentication (e.g., clear-text passwords, or outdated and vulnerable authentication or encryption protocols) or do not support multi-factor authentication. Always configure access controls on cloud resources carefully to ensure that only well-maintained and well-authenticated accounts have access.
  6. Employ appropriate network segmentation and restrictions to limit access and utilize additional attributes (such as device information, environment, access path) when making access decisions, with the desired state being a Zero Trust security model.

Use automated tools to audit access logs for security concerns and identify anomalous access requests.




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