A newly discovered vulnerability in Foxit PDF Reader allows attackers to escalate their privileges from a low-privileged user to SYSTEM level. Identified as CVE-2024-29072, this high-severity flaw, with a rating of 8.2, affects multiple versions of Foxit PDF Reader for Windows. Foxit has issued a security advisory and released patches to address this critical issue.
The vulnerability arises from improper certification validation of the updater executable before its execution. When a user initiates an update via the Help → About Foxit PDF Reader → Check For Update pathway, the software writes the FoxitPDFReaderUpdater.exe file in the %APPDATA%\Foxit Software\Continuous\Addon\Foxit PDF Reader folder and runs it under the user context. The update service then calls CryptQueryObject on this file to retrieve its certificate information but only checks for the certificate’s existence without validating it thoroughly. This check is performed under the SYSTEM context, making it a critical security flaw.
An attacker can exploit this vulnerability by using signtool.exe from Visual Studio to craft a malicious file with a self-signed certificate. By setting an opportunistic lock (oplock) on the updater executable, the attacker can replace it with the malicious file during the update process. When FoxitPDFReaderUpdateService.exe calls CryptQueryObject on the modified file, it proceeds without proper validation and executes the malicious executable with elevated privileges, effectively escalating the attacker’s access to SYSTEM level.
Users are strongly advised to update Foxit PDF Reader to the latest version immediately to protect against potential exploits. If updating is not possible, users should avoid performing updates through the vulnerable mechanism until a patch can be applied.
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