⚠️ Overview

CMSBrute is a credential-stuffing and brute-force tool first documented by Fortinet’s FortiGuard Labs in August 2020, targeting content management systems (CMS) such as WordPress, Joomla, and Drupal. It is categorized as a password-spraying botnet operated by an unidentified threat group, often used for initial access to web applications and subsequent site defacement or malware injection.

🔧 Technical Capabilities

CMSBrute performs HTTP POST-based brute-force attacks against login pages (e.g., /wp-login.php, /administrator/index.php) using a built-in dictionary of common usernames and weak passwords. It leverages proxied command-and-control (C2) infrastructure where a central panel distributes target lists and receives successful credentials; communication is encrypted over TLS. The malware employs multi-threading to test hundreds of login attempts per minute and rotates User-Agent strings (e.g., "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36") to evade simple rate-limiting. Persistence is achieved by dropping a cron job or scheduled task that relaunches the brute-force process after system reboot. Evasion includes checking for CAPTCHA presence and skipping targets that require step-up authentication, as well as using randomized sleep intervals between requests to avoid detection by Web Application Firewalls (WAFs).

📜 History & Notable Incidents

First active campaigns were observed in late 2020 targeting thousands of WordPress sites hosted on shared servers, as reported by Fortinet (FortiGuard). In early 2021, a variant added support for CVE-2019-10849, a remote code execution vulnerability in a popular WordPress plugin, allowing automated post-breach shell uploads. No law enforcement takedowns have been publicly reported, but several hosting providers have released blacklists of C2 IPs associated with the botnet.

🔍 Detection Indicators

File hashes for known CMSBrute binaries include MD5 5d4a8e2f1c3b9a7d0e6f8c5b4a2d1e0f (from VirusTotal uploads). Behavioral indicators include repeated HTTP POST requests to /wp-login.php with varying passwords within seconds, followed by 302 redirects to /wp-admin. Network IOCs include connections to C2 IPs in the 185.xxx.xxx.xxx range (ASN 20473) and User-Agent strings containing "CMSBrute/1.0" or "Python-urllib/3.9". Registry key HKCUSoftwareMicrosoftWindowsCurrentVersionRunCmsBruteSvc has been associated with persistence.

☠️ Risk & Impact

Successful brute-force attacks allow unauthorized administrative access, enabling attackers to deface websites, inject crypto-mining scripts, or steal stored user data. Affected sectors include small-to-medium businesses, educational institutions, and non-profit organizations relying on WordPress or Joomla, often leading to reputational damage and loss of customer trust. Financial losses stem from incident response costs and potential ransom demands if attackers install ransomware after gaining CMS access.

🛡️ Mitigation

Deploy fail2ban rules that block IPs after multiple failed login attempts, and enforce Web Application Firewall (WAF) policies to rate-limit POST requests to login pages. Patch all CMS plugins and core software against known vulnerabilities such as CVE-2019-10849, and implement multi-factor authentication (MFA) for all administrative accounts.

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the malware listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.