CVE-2023-39542 is a critical vulnerability classified under CWE-73 (External Control of File Name or Path) found in Foxit Reader version 12.1.3.15356. The flaw exists in the Javascript saveAs API, which is used to save files from within PDF documents. An attacker can craft a specially malformed PDF file that abuses this API to create arbitrary files on the victim’s system. This can lead to remote code execution if the attacker’s payload is executed after file creation. The attack vector requires user interaction: the victim must open the malicious PDF or visit a malicious website that triggers the vulnerability via the Foxit Reader browser plugin. The vulnerability does not require any privileges or prior authentication, making it accessible to remote attackers. The CVSS v3.1 score of 8.8 reflects the high impact on confidentiality, integrity, and availability, as arbitrary file creation can lead to system compromise. No patches or exploit code are currently publicly available, but the risk remains significant due to the ease of exploitation and potential damage. The vulnerability affects environments where Foxit Reader is used to open untrusted PDFs or where the browser plugin is enabled, increasing the attack surface. This vulnerability highlights the risks associated with embedded scripting in PDF readers and the need for strict controls on file system access from document viewers.

For European organizations, the impact of CVE-2023-39542 can be severe. Successful exploitation can lead to arbitrary file creation and remote code execution, potentially allowing attackers to install malware, steal sensitive data, or disrupt operations. Sectors such as finance, government, healthcare, and critical infrastructure, which frequently handle PDF documents, are particularly vulnerable. The compromise of endpoints running Foxit Reader can serve as a foothold for lateral movement within networks, increasing the risk of widespread breaches. The vulnerability’s reliance on user interaction means phishing campaigns or malicious websites could be effective attack vectors. Additionally, organizations using the Foxit Reader browser plugin face increased risk from drive-by attacks. The confidentiality of sensitive documents and the integrity of systems are at risk, and availability could be impacted if ransomware or destructive payloads are deployed. The lack of known exploits in the wild currently limits immediate risk but does not diminish the urgency for mitigation given the high severity and ease of exploitation.

1. Immediately disable the Foxit Reader browser plugin to reduce exposure to drive-by download attacks. 2. Avoid opening PDF files from untrusted or unknown sources until a patch is available. 3. Implement strict endpoint security controls to restrict the ability of applications to write files outside designated directories, using application whitelisting and file system permissions. 4. Monitor network traffic and endpoint behavior for suspicious file creation or execution activities related to Foxit Reader. 5. Educate users about the risks of opening unsolicited PDF attachments and visiting untrusted websites. 6. Once Foxit releases a security patch, prioritize its deployment across all affected systems. 7. Consider using alternative PDF readers with a better security track record or sandboxing PDF reader processes to limit potential damage. 8. Employ advanced threat detection tools capable of identifying exploitation attempts targeting this vulnerability.