In October 2023, multiple PDF-related vulnerabilities were discovered in Google Chrome that could lead to arbitrary code execution attacks.

In the CVE-2023-5474 example (which earned an exceptionally high base severity score of 8.8 in the National Vulnerability Database), a remote attacker could trigger a heap buffer overflow in a victim’s web browser by convincing them to interact with certain features of a specially crafted malicious PDF file.

Understanding the Severity of Heap Buffer Overflows

Heap buffer overflows occur when a program writes more data to a heap memory buffer than the buffer is supposed to handle. This memory "overflow" can cause data stored in adjacent memory buffers to become corrupted, causing the application to crash or possibly leak sensitive data to the attacker. If the overwritten memory buffers contain function pointers or other control data, attackers can go as far as hijacking the program’s execution flow, resulting in the dreaded arbitrary code execution attack.

In the case of CVE-2023-5474, arbitrary code execution was a possible outcome. If the attack involved a victim with escalated privileges in their system, it could allow the attacker to install new programs, view and change sensitive data, or even create entirely new user accounts.

Mitigating Vulnerabilities like CVE-2023-5474

Google Chrome has since patched this specific vulnerability with application updates. Regardless, the significance of CVE-2023-5474 – and other vulnerabilities which follow a similar pattern – cannot be understated. No viruses or malware are directly involved in the process of exploiting this type of CVE, meaning traditional antivirus software won’t identify any threats in the file the attacker crafts to trigger the heap buffer overflow.

Mitigating a threat like this requires:

1. Regularly checking the affected application for updates (in this case, the Google Chrome web browser) and installing them.
2. Verifying that all PDFs reaching sensitive locations (i.e., where a user might be able to open them) are thoroughly verified to ensure their contents rigorously conform to PDF formatting standards.

Scanning and Verifying Malicious PDFs with Cloudmersive

The Cloudmersive Advanced Virus Scan API combines virus and malware scanning with in-depth content verification to provide 360-degree protection against files entering an application (or network). Performing a dynamic threat scan on PDFs intended to exploit vulnerabilities like CVE-2023-5474 can identify issues with the file that may have otherwise resulted in zero-day heap buffer overflow attacks in any one of the PDF rendering or parsing programs that our applications utilize in the background.

For more information on how the Cloudmersive Advanced Virus Scan API can help protect your applications or network against invalid file threats, please do not hesitate to reach out to a member of our sales team.