CVE-2018-15955 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat and Reader versions 2018.011.20063 and earlier, 2017.011.30102 and earlier, and 2015.006.30452 and earlier have an out-of-bounds write vulnerability. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 03/31/2020
Adobe Acrobat and Reader applications contain a critical out-of-bounds write vulnerability that affects multiple versions across different release cycles. This vulnerability resides in the handling of specific file formats and occurs when the software processes malformed input data without proper bounds checking mechanisms. The flaw allows an attacker to write data beyond the allocated memory buffer, potentially corrupting adjacent memory locations and enabling arbitrary code execution. The vulnerability is classified as a classic buffer overflow condition that can be exploited through crafted malicious documents or files. This type of vulnerability falls under CWE-787 Out-of-bounds Write which represents one of the most dangerous categories of memory corruption flaws in software applications. The vulnerability affects users who open or process specially crafted PDF files, making it particularly concerning for enterprise environments where document processing is common. Attackers can leverage this weakness to execute malicious code with the privileges of the affected application, potentially leading to complete system compromise.
The technical exploitation of this vulnerability requires careful crafting of input data that triggers the buffer overflow condition during document parsing operations. When Adobe Acrobat or Reader processes a maliciously constructed file, the application fails to validate the size or boundaries of memory allocations, allowing an attacker to overwrite critical memory regions. This memory corruption can be leveraged to redirect program execution flow, inject malicious code, or manipulate application behavior. The vulnerability's impact extends beyond simple code execution as it can be combined with other techniques to bypass modern security protections such as address space layout randomization and data execution prevention. Security researchers have identified that the flaw occurs during parsing of specific PDF objects or streams where the software does not properly validate array indices or buffer sizes. The exploitation process typically involves creating a specially formatted PDF document that, when opened by the vulnerable software, triggers the memory corruption. This attack vector aligns with ATT&CK technique T1203 Exploitation for Client Execution which describes how adversaries use vulnerabilities in software to execute malicious code on target systems. The vulnerability affects all versions mentioned in the CVE description, including 2018.011.20063 and earlier, 2017.011.30102 and earlier, and 2015.006.30452 and earlier, indicating a long-standing issue that spans multiple product releases.
Organizations and users must implement immediate mitigations to protect against exploitation of this vulnerability. The most effective defense is to update to the latest versions of Adobe Acrobat and Reader where the vulnerability has been patched by Adobe. Security patches typically include enhanced input validation, bounds checking mechanisms, and memory protection features that prevent the buffer overflow condition from occurring. System administrators should also consider implementing additional security controls such as sandboxing, application whitelisting, and restricted file type handling for PDF documents. Network-level protections can include content filtering solutions that scan PDF files for known malicious patterns or suspicious structures that may indicate exploitation attempts. Users should be educated about the risks of opening untrusted PDF files and should avoid downloading documents from unknown sources. The vulnerability's potential for remote code execution makes it particularly dangerous in enterprise environments where users may inadvertently open malicious attachments or documents. Security monitoring should include detection of unusual application behavior or memory access patterns that might indicate exploitation attempts. Organizations should also consider implementing zero-trust security models that limit the execution of potentially malicious code even within trusted network environments. Regular vulnerability assessments and penetration testing can help identify systems that may still be running vulnerable versions of Adobe software, ensuring comprehensive protection against this and similar threats.