CVE-2017-16362 in Acrobat Reader
Summary
by MITRE
An issue was discovered in Adobe Acrobat and Reader: 2017.012.20098 and earlier versions, 2017.011.30066 and earlier versions, 2015.006.30355 and earlier versions, and 11.0.22 and earlier versions. This vulnerability is an instance of an out of bounds read vulnerability in the MakeAccesible plugin, when handling font data. It causes an out of bounds memory access, which sometimes triggers an access violation exception. Attackers can exploit the vulnerability by using the out of bounds access for unintended reads, writes, or frees, potentially leading to code corruption, control-flow hijack, or an information leak attack.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/03/2024
This vulnerability resides within Adobe Acrobat and Reader software versions up to specific patch levels including 2017.012.20098, 2017.011.30066, 2015.006.30355, and 11.0.22, representing a critical out of bounds read condition in the MakeAccesible plugin component. The flaw manifests when processing font data structures, specifically in how the plugin handles memory access patterns during accessibility conversion operations. This particular vulnerability classifies under CWE-125 as an out-of-bounds read, which represents a fundamental memory safety issue where program code attempts to access memory locations beyond the allocated buffer boundaries. The technical implementation involves the MakeAccesible plugin's insufficient validation of font metadata structures, particularly when encountering malformed or unexpected font data formats that trigger memory access violations.
The operational impact of this vulnerability extends beyond simple application instability, as it provides attackers with potential pathways for more sophisticated exploitation techniques. When the out of bounds read occurs during font processing, the memory access violation can be leveraged to perform unintended reads from adjacent memory regions, potentially exposing sensitive data such as stack canaries, heap metadata, or other program variables. This memory disclosure capability aligns with ATT&CK technique T1059.007 for data exfiltration through memory access manipulation. The vulnerability's exploitation potential increases significantly because it can lead to information disclosure attacks where attackers extract memory contents that might contain encryption keys, user credentials, or application state information.
From a security perspective, this vulnerability demonstrates how seemingly benign document processing functionality can become a vector for more serious attacks. The MakeAccesible plugin is designed to convert documents into accessible formats for users with disabilities, but the implementation lacks proper bounds checking when handling font resources. Attackers can craft malicious PDF documents containing specially formatted font data that triggers the out of bounds read condition, potentially leading to a control flow hijack if the memory corruption affects program execution paths. The vulnerability's exploitation requires the target application to process a malicious document, making it a classic example of a remote code execution vector through document parsing. The memory corruption potential, combined with the ability to perform unintended memory operations, makes this vulnerability particularly dangerous in targeted attack scenarios.
Mitigation strategies for this vulnerability should focus on immediate software updates to patched versions, as Adobe has released security updates addressing the specific bounds checking issues in the MakeAccesible plugin. Organizations should implement network segmentation and document filtering measures to prevent untrusted PDF files from reaching end-user systems, particularly in environments where users have elevated privileges. The vulnerability also highlights the importance of input validation and memory safety practices in document processing libraries, aligning with security standards that emphasize defensive programming techniques. Additionally, implementing application sandboxing and privilege separation mechanisms can limit the potential impact of successful exploitation attempts, while regular security assessments of document processing components can help identify similar vulnerabilities in other software libraries.