CVE-2017-16420 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 occurs as a result of a computation that reads data that is past the end of the target buffer; the computation is in the part of the JavaScript engine that handles annotation abstraction. The use of an invalid (out-of-range) pointer offset during access of internal data structure fields causes the vulnerability. A successful attack can lead to sensitive data exposure.
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Analysis
by VulDB Data Team • 09/03/2024
This vulnerability exists in Adobe Acrobat and Reader applications across multiple versions including 2017.012.20098 and earlier, 2017.011.30066 and earlier, 2015.006.30355 and earlier, and 11.0.22 and earlier. The flaw manifests within the JavaScript engine's handling of annotation abstraction where a buffer overread condition occurs during data processing. The vulnerability stems from improper bounds checking when accessing internal data structures, specifically when computing pointer offsets that reference memory locations beyond the allocated buffer boundaries. This type of memory safety issue represents a classic buffer overflow vulnerability pattern that can be exploited to access unauthorized memory regions.
The technical implementation of this vulnerability involves the JavaScript engine's annotation abstraction layer where memory access computations extend beyond valid buffer limits. When the engine processes annotation objects, it performs calculations that result in pointer arithmetic producing offsets that point to memory locations outside the intended data structure boundaries. This out-of-range memory access can be manipulated by an attacker to read sensitive information from adjacent memory regions, potentially exposing confidential data including credentials, personal information, or proprietary documents that may be stored in memory. The vulnerability operates at the intersection of memory management and JavaScript execution, making it particularly dangerous in document processing environments where arbitrary code execution could be achieved through carefully crafted malicious documents.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more sophisticated attacks within the context of document processing. An attacker could construct malicious PDF documents containing specially crafted annotations that trigger the buffer overread condition when opened by vulnerable versions of Adobe Acrobat or Reader. This could result in exposure of sensitive data stored in memory, including but not limited to user credentials, system information, or document contents that may be temporarily resident in memory. The vulnerability's presence in multiple version ranges indicates a widespread issue affecting both older and newer releases, suggesting that the underlying memory management flaw was not properly addressed across the product lifecycle. According to CWE classification, this represents a CWE-125: Out-of-bounds Read vulnerability, which is categorized under the broader weakness of improper access control in memory management.
Mitigation strategies should focus on immediate patch application to the affected Adobe products, as the vendor has released security updates addressing this specific vulnerability. Organizations should implement strict document handling policies that limit exposure to potentially malicious PDF files, particularly those originating from untrusted sources. Network-level controls including web application firewalls and content filtering solutions can help prevent the delivery of malicious documents to end users. Additionally, security monitoring should be enhanced to detect unusual patterns in PDF processing activities that may indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving privilege escalation and credential access through memory corruption vulnerabilities, making it a critical target for defensive measures. Regular security assessments and vulnerability scanning should be conducted to ensure all Adobe installations remain current with security patches, while user education regarding safe document handling practices remains essential in preventing successful exploitation attempts.