A vulnerability was recently discovered in Apache Struts, a popular framework for web-based Java applications, which allows for remote code execution on affected servers and allows for complete control of the application. The framework is commonly used by large, sophisticated organizations such as Lockheed Martin and Citigroup, meaning the vulnerability could affect up to 65% of Fortune 100 companies, resulting in large scale data breaches and private consumer data theft.

Found by lgtm.com security researcher Man Yue Mo, the vulnerability stems from unsafe deserialization of user supplied data to the REST plugin, which allows API access to the Java application. Researchers contacted the Apache Foundation directly, allowing the plugin developers to patch the issue before widespread exploitation. As of this writing, at least one live exploit has been seen in the wild, and a Metasploit module was released.

Apache Struts joins a growing fraternity of widely used applications to see an API vulnerability this year, including WordPress and Instagram. WordPress shared a similar experience where the exploit was discovered before widespread attacks, but many users failed to update and suffered compromise and data loss. The Struts vulnerability is more complicated to exploit which should result in a less dramatic rise in attacks. Regardless, patches should be applied as soon as possible, as a proactive security stance is more effective.

Apache Struts users are urged to upgrade to version 2.3.34 or 2.5.13 respectively, and additional information is provided by Apache on the official struts webpage at: https://cwiki.apache.org/confluence/display/WW/Version+Notes+2.3.34 and   https://struts.apache.org/announce.html#a20170905.

More sophisticated exploits are likely to occur as this vulnerability is examined. The best option for mitigation is to patch Struts as soon as possible to the recommended versions and regularly check for updates. Website owners should also consider adding a web application firewall and malware scanner to mitigate or reduce the severity of compromise.

SiteLock TrueShield customers are already protected against this exploit. Attempted attacks will be caught and blocked by the TrueShield WAF. If your website isn’t protected, call SiteLock at 888.878.2417 to get TrueShield installed today.