CVE-2018-5025 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat and Reader 2018.011.20040 and earlier, 2017.011.30080 and earlier, and 2015.006.30418 and earlier versions have an Out-of-bounds read vulnerability. Successful exploitation could lead to information disclosure.
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Analysis
by VulDB Data Team • 08/11/2024
Adobe Acrobat and Reader versions prior to 2018.011.20040, 2017.011.30080, and 2015.006.30418 contain a critical out-of-bounds read vulnerability that stems from improper input validation within the document parsing functionality. This vulnerability falls under the CWE-129 weakness category, specifically addressing insufficient validation of the length of input data. The flaw occurs when the application processes malformed PDF files that contain crafted array indices or buffer sizes that exceed the allocated memory boundaries. When the software attempts to read memory locations beyond the valid buffer limits, it may access uninitialized or protected memory regions, potentially exposing sensitive information stored in adjacent memory segments. The vulnerability exists in the PDF parsing engine where array bounds checking is inadequate during the processing of complex document structures such as embedded objects, streams, or metadata sections. Attackers can exploit this by crafting malicious PDF documents that trigger the out-of-bounds read condition when the vulnerable software attempts to parse and render the document content. This type of vulnerability aligns with the ATT&CK technique T1203 - Exploitation for Client Execution, as it enables attackers to execute arbitrary code or extract sensitive data through crafted PDF files. The information disclosure aspect of this vulnerability can potentially reveal memory contents including cryptographic keys, user credentials, or system information that may aid in further exploitation. The impact extends beyond simple information leakage as the exposed memory regions could contain pointers, stack frames, or other sensitive data structures that could be leveraged for more sophisticated attacks. This vulnerability represents a classic example of memory safety issues that have been prevalent in document processing software due to the complex nature of PDF file structures and the extensive parsing required to handle various embedded content types. Organizations using affected Adobe products should prioritize immediate patching to prevent potential exploitation by threat actors who may develop automated tools to leverage this vulnerability for unauthorized data access.
The technical implementation of this vulnerability demonstrates how improper bounds checking in array access operations can lead to memory corruption issues. When Adobe Reader processes a PDF file, it must parse various data structures including arrays, dictionaries, and streams that define the document's content and formatting. In the vulnerable versions, the application fails to validate array indices against the actual size of the allocated buffer, allowing an attacker to manipulate the parsing process through carefully constructed PDF elements. The out-of-bounds read condition typically occurs when the software attempts to access array elements that extend beyond the allocated memory boundaries, potentially reading from adjacent memory locations that contain other data structures or sensitive information. This type of vulnerability is particularly dangerous in document viewers because users frequently open PDF files from untrusted sources, making the attack surface broad and accessible. The exploitation requires minimal privileges and can be accomplished through social engineering techniques where users unknowingly open malicious PDF attachments. The vulnerability's classification as CWE-129 indicates that it stems from insufficient validation of input data length, which is a common pattern in software development where developers assume input data will conform to expected formats without proper bounds checking. This weakness is particularly prevalent in languages like C and C++ where memory management is manual and bounds checking is not enforced by default, though the vulnerability exists in the application's design rather than the underlying programming language itself. The potential for information disclosure makes this vulnerability particularly attractive to attackers who may use it as a stepping stone for more advanced exploitation techniques.
The operational impact of CVE-2018-5025 extends far beyond simple data exposure, as it creates opportunities for attackers to gather intelligence that could facilitate more sophisticated attacks. When the out-of-bounds read occurs, the application may expose memory contents that include stack canaries, return addresses, or other sensitive data structures that could be used to bypass security mechanisms such as stack buffer overflow protections or address space layout randomization. The vulnerability affects multiple versions of Adobe Reader and Acrobat, creating a substantial attack surface across enterprise environments where these applications are commonly deployed. Organizations with legacy systems or delayed patch management processes face heightened risk as the vulnerability remains exploitable for extended periods. The information disclosure aspect of this vulnerability can reveal cryptographic material, user session data, or internal application state information that could be leveraged for privilege escalation or lateral movement within network environments. Security teams must consider this vulnerability in their risk assessment frameworks as it represents a persistent threat that can be exploited without requiring elevated privileges or specialized attack infrastructure. The vulnerability's exploitation does not require complex attack chains, making it particularly dangerous for organizations with limited security awareness training. Incident response procedures should include detection of potential exploitation attempts through network monitoring for malicious PDF file transfers and endpoint monitoring for abnormal memory access patterns. The vulnerability's presence in widely used document processing software means that organizations cannot assume their systems are immune to exploitation, even when they maintain robust security controls in other areas of their infrastructure. This makes the vulnerability particularly concerning for industries that handle sensitive data or operate in highly regulated environments where data protection is paramount. Organizations should implement comprehensive patch management processes that prioritize critical vulnerabilities like this one to prevent potential data breaches or unauthorized access incidents.
Mitigation strategies for CVE-2018-5025 should include immediate patch deployment as the primary defense mechanism, as Adobe released security updates to address the specific out-of-bounds read conditions in affected versions. Organizations should implement strict document validation policies that prevent automatic execution of potentially malicious content and configure Adobe Reader to run in restricted mode where possible. Network security controls should be enhanced to detect and block suspicious PDF file transfers, including implementation of content inspection rules that identify malformed PDF structures. Endpoint protection solutions should be configured to monitor for abnormal memory access patterns that could indicate exploitation attempts, and security information and event management systems should be tuned to detect potential exploitation signatures. Organizations should also consider implementing sandboxing technologies for PDF processing to isolate potentially malicious documents from critical system resources. Regular vulnerability assessments should include scanning for unpatched Adobe Reader installations across the enterprise to identify remaining exposure. Security awareness training should emphasize the dangers of opening PDF attachments from unknown sources, as this vulnerability is commonly exploited through social engineering campaigns. The mitigation approach should also include maintaining updated threat intelligence feeds that provide information about active exploitation attempts targeting this vulnerability, enabling organizations to respond proactively to emerging threats. Additionally, organizations should consider implementing application control policies that restrict the execution of Adobe Reader and Acrobat applications to trusted environments, reducing the attack surface for exploitation. Regular security audits should verify that patch management processes are effectively addressing this vulnerability and that no legacy systems remain unpatched. The combination of these defensive measures provides a comprehensive approach to mitigating the risks associated with this out-of-bounds read vulnerability in Adobe's document processing applications.