CVE-2014-8452 in Acrobat Reader
Summary
by MITRE
Adobe Reader and Acrobat 10.x before 10.1.13 and 11.x before 11.0.10 on Windows and OS X allow remote attackers to read arbitrary files via an XML external entity declaration in conjunction with an entity reference, related to an XML External Entity (XXE) issue.
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Analysis
by VulDB Data Team • 02/28/2022
Adobe Reader and Acrobat versions 10.x prior to 10.1.13 and 11.x prior to 11.0.10 contain a critical XML External Entity vulnerability that enables remote attackers to access arbitrary files on the target system. This vulnerability stems from the software's insufficient validation of XML content, specifically when processing XML documents that contain external entity declarations. The flaw occurs when the application processes XML files that include entity references pointing to external resources, allowing malicious actors to construct specially crafted XML documents that can trigger unauthorized file access. The vulnerability is classified under CWE-611 as an Improper Restriction of XML External Entity Reference, which represents a well-known weakness in XML processing implementations that has been documented in numerous security advisories over the years. The XXE vulnerability in these Adobe products demonstrates a fundamental failure in input validation and secure XML parsing practices, where the software does not properly restrict access to external entities during XML document processing. Attackers can exploit this weakness by crafting XML documents that reference external entities pointing to local files on the victim's system, thereby enabling arbitrary file read operations that can potentially expose sensitive data, configuration files, or system resources. The impact is particularly severe on Windows and OS X platforms where Adobe Reader and Acrobat are commonly deployed, as these systems often contain valuable corporate or personal information within their file structures. This vulnerability allows for information disclosure attacks that can lead to data breaches, privilege escalation, and potentially further exploitation opportunities within the compromised environment.
The technical exploitation of this XXE vulnerability requires an attacker to craft a malicious XML document that contains both external entity declarations and entity references that point to sensitive files on the target system. When Adobe Reader or Acrobat processes such a document, the application attempts to resolve the external entity references, which can result in the disclosure of file contents to the attacker. The vulnerability specifically affects the XML processing libraries used within Adobe's products, where the security controls are insufficient to prevent access to local files through entity expansion. This type of attack can be particularly effective because it leverages the legitimate XML parsing functionality of the software while exploiting the lack of proper security controls. The attack vector is remote, meaning that an attacker can deliver the malicious XML document through email attachments, web downloads, or other network-based delivery mechanisms. The exploitation process typically involves creating XML content with external entity declarations that reference local files using file:// URI schemes or similar mechanisms. The vulnerability affects not only the reading of arbitrary files but also potentially exposes the underlying file system structure, which can provide attackers with additional reconnaissance information for further attacks. Security researchers have noted that this vulnerability is particularly dangerous because it can be exploited without requiring any special privileges or authentication, making it a high-value target for attackers seeking to gain unauthorized access to sensitive information.
Organizations and users affected by this vulnerability face significant operational risks that extend beyond simple information disclosure. The ability to read arbitrary files from the target system can lead to the exposure of sensitive corporate data, personal information, or system configuration details that can be used for further attacks. The vulnerability can potentially be exploited to access files containing passwords, encryption keys, or other credentials that could lead to privilege escalation or lateral movement within a network. From an attacker's perspective, this vulnerability provides a straightforward path to data exfiltration without requiring complex exploitation techniques or elevated privileges. The widespread deployment of Adobe Reader and Acrobat across enterprise environments makes this vulnerability particularly attractive to threat actors targeting corporate networks. The impact on business operations can be substantial, as successful exploitation can result in regulatory compliance violations, financial losses, and damage to organizational reputation. Security professionals have documented similar XXE vulnerabilities in other software applications, highlighting the persistent nature of this class of vulnerability in XML processing implementations. The vulnerability also demonstrates the importance of proper input validation and secure coding practices in preventing such issues. Organizations should consider this vulnerability in the context of broader security frameworks, including the ATT&CK framework's techniques for privilege escalation and credential access, where XXE vulnerabilities can serve as initial access vectors for more sophisticated attacks. The exploitation of this vulnerability can be automated, making it particularly dangerous in environments where users frequently open email attachments or download content from untrusted sources.
Mitigation strategies for this XXE vulnerability should focus on both immediate remediation and long-term security improvements. The most effective immediate solution is to update Adobe Reader and Acrobat to versions 10.1.13 or 11.0.10, which contain patches addressing the XML external entity processing issues. Organizations should implement comprehensive patch management procedures to ensure that all systems running Adobe products are updated promptly. Beyond patching, security administrators should consider implementing network-level controls to restrict access to external resources and limit the ability of XML documents to reference external entities. Input validation controls should be strengthened to prevent the processing of XML documents containing potentially dangerous external entity declarations. Security monitoring should be enhanced to detect unusual XML processing activities or attempts to access sensitive files. Organizations should also consider deploying web application firewalls or XML gateways that can filter out potentially malicious XML content before it reaches the target applications. The implementation of security awareness training for users can help reduce the risk of exploitation through social engineering attacks that deliver malicious XML files. From a compliance perspective, organizations should ensure that their security measures align with industry standards such as the NIST Cybersecurity Framework and ISO 27001 requirements for secure information processing. The vulnerability also highlights the importance of maintaining up-to-date vulnerability assessments and penetration testing procedures to identify similar weaknesses in other software applications. Regular security audits should include checks for proper XML processing controls and external entity handling within applications. The security community has recognized XXE vulnerabilities as persistent threats requiring continuous vigilance and proactive security measures to prevent exploitation.