CVE-2020-35931 Explained : Impact and Mitigation

An issue was discovered in Foxit Reader before 10.1.1 (and before 4.1.1 on macOS) and PhantomPDF before 9.7.5 and 10.x before 10.1.1 (and before 4.1.1 on macOS). An attacker can spoof a certified PDF document via an Evil Annotation Attack because the products fail to consider a null value for a Subtype entry of the Annotation dictionary, in an incremental update.

Understanding CVE-2020-35931

This CVE identifies a vulnerability in Foxit Reader and PhantomPDF that allows attackers to spoof certified PDF documents.

What is CVE-2020-35931?

The CVE-2020-35931 vulnerability in Foxit Reader and PhantomPDF enables attackers to perform Evil Annotation Attacks by exploiting a flaw in handling null values in the Annotation dictionary.

The Impact of CVE-2020-35931

The vulnerability could lead to the spoofing of certified PDF documents, potentially allowing attackers to deceive users into interacting with malicious content.

Technical Details of CVE-2020-35931

This section provides technical insights into the CVE-2020-35931 vulnerability.

Vulnerability Description

The issue arises from a failure to account for null values in the Subtype entry of the Annotation dictionary during an incremental update process.

Affected Systems and Versions

Foxit Reader versions before 10.1.1 (4.1.1 on macOS)
PhantomPDF versions before 9.7.5 and 10.x before 10.1.1 (4.1.1 on macOS)

Exploitation Mechanism

Attackers can exploit this vulnerability to create malicious annotations in PDF documents, potentially leading to spoofing attacks.

Mitigation and Prevention

Protecting systems from CVE-2020-35931 requires immediate actions and long-term security practices.

Immediate Steps to Take

Update Foxit Reader and PhantomPDF to the latest versions.
Be cautious when opening PDF files from untrusted sources.

Long-Term Security Practices

Regularly update software and security patches.
Educate users on identifying suspicious PDF content.

Patching and Updates

Ensure that Foxit Reader and PhantomPDF are regularly updated with the latest security patches to mitigate the CVE-2020-35931 vulnerability.