CVE-2018-4995 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat and Reader versions 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 and earlier have an XFA \n POST injection vulnerability. Successful exploitation could lead to a security bypass.
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Analysis
by VulDB Data Team • 07/22/2024
The vulnerability identified as CVE-2018-4995 affects Adobe Acrobat and Reader software across multiple version ranges including 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 and earlier. This represents a critical security flaw within the XML Forms Architecture (XFA) processing functionality of these applications. The vulnerability manifests as an XFA POST injection vulnerability that allows attackers to manipulate the data submitted through XFA forms, potentially bypassing security controls that would normally protect against malicious input. The flaw resides in how these applications handle XFA form data during POST requests, creating an opportunity for attackers to inject malicious payloads that can be executed within the context of the vulnerable software. This vulnerability falls under the CWE-74 category of Improper Neutralization of Special Elements in Output Used by a Downstream Component, specifically within the context of form processing and data injection attacks. The security implications are significant as this vulnerability could enable attackers to bypass authentication mechanisms, execute arbitrary code, or gain unauthorized access to sensitive information within the system where the vulnerable software is installed.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious XFA form that contains specially constructed POST data which, when processed by the vulnerable Adobe application, triggers unintended behavior. The injection occurs during the form submission process where the application fails to properly validate or sanitize the POST parameters before processing them. This allows attackers to inject additional form fields or modify existing ones in a way that can influence the application's execution flow. The attack typically involves creating a malicious PDF document containing an XFA form that, when opened and submitted, sends crafted data to a remote server or executes malicious code on the victim's system. The vulnerability demonstrates a classic example of how form processing flaws can be exploited to bypass security controls, particularly when applications fail to properly validate user input before processing it. According to ATT&CK framework, this vulnerability maps to T1059.007 for Command and Scripting Interpreter and T1068 for Exploitation for Privilege Escalation, as the successful exploitation could lead to unauthorized system access and privilege escalation opportunities.
The operational impact of CVE-2018-4995 extends beyond simple data injection, as it represents a fundamental flaw in how Adobe applications handle form data processing. Organizations using vulnerable versions of Adobe Acrobat and Reader face significant risks including potential data breaches, unauthorized system access, and compromise of sensitive information. The vulnerability is particularly concerning because PDF documents are widely used in business environments and often contain sensitive data, making them prime targets for attackers. Successful exploitation could allow attackers to bypass security controls that would normally protect against malicious input, potentially leading to full system compromise. The widespread adoption of Adobe Reader across enterprises makes this vulnerability particularly dangerous, as a single compromised document could affect multiple users within an organization. The vulnerability also creates opportunities for attackers to perform privilege escalation attacks, as the injection could potentially allow execution of code with elevated privileges. Organizations that rely on PDF document processing for business operations face increased risk of security incidents, including potential insider threats and external attacks targeting their document processing infrastructure. The security bypass capability means that traditional security controls such as input validation, access controls, and data sanitization may be rendered ineffective against this specific attack vector.
Mitigation strategies for CVE-2018-4995 should include immediate patching of all affected Adobe Acrobat and Reader installations to the latest versions that contain the necessary security fixes. Organizations should also implement strict document handling policies, including the use of sandboxed environments for opening PDF documents and implementing network-based security controls to monitor and filter XFA form submissions. The implementation of web application firewalls and intrusion detection systems can help identify and block malicious XFA form data before it reaches vulnerable applications. Additionally, organizations should consider disabling XFA form processing entirely if it is not required for business operations, as this would eliminate the attack surface entirely. Security awareness training for end users should emphasize the importance of not opening PDF documents from untrusted sources and the potential risks associated with XFA forms. Regular vulnerability assessments and penetration testing should be conducted to identify other potential injection vulnerabilities within the organization's PDF processing infrastructure. The remediation process should also include monitoring for any signs of exploitation attempts and implementing comprehensive logging of all PDF form processing activities to enable forensic analysis if incidents occur. According to industry best practices and security frameworks, organizations should maintain up-to-date threat intelligence feeds to stay informed about similar vulnerabilities and exploit techniques that could affect their PDF processing environments.