CVE-2017-3020 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat Reader versions 11.0.19 and earlier, 15.006.30280 and earlier, 15.023.20070 and earlier have a memory address leak vulnerability in the weblink module.
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Analysis
by VulDB Data Team • 08/29/2020
The vulnerability identified as CVE-2017-3020 affects Adobe Acrobat Reader software across multiple version ranges including 11.0.19 and earlier, 15.006.30280 and earlier, and 15.023.20070 and earlier. This memory address leak occurs within the weblink module of the application, representing a critical security flaw that could be exploited by malicious actors to gain unauthorized access to system resources. The vulnerability stems from improper handling of memory addresses during the processing of web links within PDF documents, creating potential attack vectors that extend beyond simple document viewing operations. The weblink module is specifically designed to handle external hyperlinks and web navigation within PDF files, making it a prime target for exploitation as users frequently interact with these elements during document review processes.
The technical flaw manifests as a memory address leak that occurs when the weblink module processes certain malformed or crafted PDF elements containing external links. This type of vulnerability falls under the category of memory corruption issues, specifically aligning with CWE-467, which addresses the use of sizeof() on a pointer type rather than an array type, and potentially CWE-122, which covers heap-based buffer overflow conditions. The memory address leak vulnerability allows attackers to potentially extract sensitive information from the application's memory space, including pointers to internal structures, stack addresses, or other critical memory locations that could be leveraged for more sophisticated attacks. This memory disclosure occurs when the application fails to properly validate or sanitize input data from web link elements within PDF documents, creating opportunities for information leakage that could aid in bypassing security mitigations.
The operational impact of this vulnerability extends significantly beyond the immediate memory leak, as it provides attackers with valuable information that can be used to circumvent modern exploit mitigations such as address space layout randomization and stack canaries. When an attacker successfully triggers this memory address leak, they can potentially obtain stack or heap addresses that reveal the memory layout of the running Acrobat Reader process, making subsequent exploitation attempts more reliable and effective. The vulnerability is particularly concerning because it affects widely deployed software used across enterprise environments, where users regularly open PDF documents from untrusted sources, creating numerous potential attack vectors for remote code execution or privilege escalation scenarios. This type of vulnerability aligns with ATT&CK technique T1059, which covers command and scripting interpreter usage, as attackers could leverage the leaked memory addresses to craft more precise exploitation payloads.
Mitigation strategies for CVE-2017-3020 should prioritize immediate software updates to the latest versions of Adobe Acrobat Reader, as Adobe has released patches addressing this specific memory address leak vulnerability. Organizations should implement network segmentation and application whitelisting policies to limit the exposure of Acrobat Reader installations to untrusted PDF content, while also deploying web application firewalls and content filtering solutions to scan and validate PDF documents before they reach end-user systems. Security teams should consider disabling the weblink module entirely in environments where PDF documents from external sources are frequently processed, and implement regular vulnerability scanning to identify systems running vulnerable versions of the software. Additionally, user education regarding the dangers of opening PDF documents from untrusted sources and the importance of keeping software updated remains crucial in preventing exploitation of this memory address leak vulnerability. The remediation process should also include monitoring for suspicious memory access patterns and implementing process isolation techniques to limit the potential impact if exploitation does occur, as this vulnerability represents a foundational security issue that could enable more serious attacks within compromised systems.