CVE-2018-17694 in Foxit
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Foxit PhantomPDF 9.2.0.9297. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the handling of the display property of a button. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-7138.
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Analysis
by VulDB Data Team • 08/01/2024
This vulnerability resides in Foxit PhantomPDF version 9.2.0.9297 and represents a critical remote code execution flaw that can be exploited through web-based attacks. The vulnerability stems from insufficient input validation within the PDF viewer's handling of button display properties, creating a dangerous condition where an attacker can manipulate object references without proper existence verification. The flaw specifically manifests when the application processes a button element's display property, failing to validate whether the referenced object actually exists before attempting operations on it. This type of vulnerability falls under the CWE-476 category of Null Pointer Dereference, where the application assumes an object exists when it may not, leading to unpredictable behavior and potential code execution. The attack vector requires user interaction, meaning victims must either visit a malicious webpage or open a specially crafted malicious PDF file to trigger the exploit. This makes the vulnerability particularly dangerous in phishing campaigns or targeted attacks where social engineering plays a crucial role in delivery.
The technical implementation of this vulnerability involves the application's failure to perform proper object validation before executing operations on button elements within PDF documents. When processing a PDF file containing a malicious button object, the PhantomPDF application attempts to access or modify the display property without first confirming that the button object reference is valid. This lack of validation creates a scenario where an attacker can craft a PDF document with malformed or malicious object references that, when processed by the vulnerable software, cause the application to execute arbitrary code with the privileges of the current user process. The vulnerability exists at the application layer where PDF parsing logic fails to implement proper defensive programming practices, particularly around object lifecycle management and reference validation. This type of flaw is classified as a remote code execution vulnerability under the ATT&CK framework's T1203 technique, which encompasses the exploitation of software vulnerabilities to execute code remotely.
The operational impact of this vulnerability extends beyond simple code execution, as it allows attackers to potentially gain complete control over the victim's system. Since the exploit executes within the context of the current process, attackers can leverage this privilege to perform actions such as installing malware, modifying system files, accessing sensitive data, or establishing persistence mechanisms. The vulnerability affects the integrity and confidentiality of the system, as it provides an attack surface that can be exploited to compromise the entire user environment. Organizations using Foxit PhantomPDF version 9.2.0.9297 are particularly at risk, as the vulnerability can be triggered through common attack vectors such as malicious email attachments, compromised websites, or drive-by downloads. The remote nature of the exploit means that attackers do not need physical access to the target system, making it a significant concern for enterprise environments where PDF documents are frequently shared and opened by multiple users.
Mitigation strategies for this vulnerability should focus on immediate remediation through software updates from Foxit, as well as implementing defensive measures to reduce the attack surface. Organizations should prioritize patching their Foxit PhantomPDF installations to versions that address this specific validation flaw. Additionally, implementing web filtering solutions, email security measures, and user education programs can help reduce the likelihood of successful exploitation attempts. Network-based protections such as intrusion detection systems can monitor for known exploit patterns associated with this vulnerability, while endpoint protection solutions should be configured to restrict PDF document handling in potentially untrusted environments. The vulnerability demonstrates the importance of proper input validation and defensive programming practices, emphasizing that all external inputs, including those from PDF documents, must be validated before processing. Organizations should also consider implementing application whitelisting policies that restrict the execution of PDF viewers to trusted environments and regularly audit their software inventory to identify and remediate other potentially vulnerable applications that may share similar architectural flaws.