CVE-2016-6968 in Acrobat Reader
Summary
by MITRE
Use-after-free vulnerability in Adobe Reader and Acrobat before 11.0.18, Acrobat and Acrobat Reader DC Classic before 15.006.30243, and Acrobat and Acrobat Reader DC Continuous before 15.020.20039 on Windows and OS X allows attackers to execute arbitrary code via unspecified vectors, a different vulnerability than CVE-2016-1089, CVE-2016-1091, CVE-2016-6944, CVE-2016-6945, CVE-2016-6946, CVE-2016-6949, CVE-2016-6952, CVE-2016-6953, CVE-2016-6961, CVE-2016-6962, CVE-2016-6963, CVE-2016-6964, CVE-2016-6965, CVE-2016-6967, CVE-2016-6969, CVE-2016-6971, CVE-2016-6979, CVE-2016-6988, and CVE-2016-6993.
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Analysis
by VulDB Data Team • 10/18/2024
The vulnerability identified as CVE-2016-6968 represents a critical use-after-free flaw in Adobe Reader and Acrobat products across multiple versions and operating systems. This security weakness affects Adobe Reader versions prior to 11.0.18, Acrobat versions before 11.0.18, and various Adobe Acrobat Reader DC Classic and Continuous versions before their respective patches. The vulnerability specifically impacts Windows and macOS operating systems, creating a significant attack surface for malicious actors seeking to exploit this weakness. The flaw allows attackers to execute arbitrary code through unspecified vectors, making it particularly dangerous as the exact exploitation method remains undisclosed while the potential impact is well-established. This vulnerability is distinct from numerous other CVEs published in the same timeframe, indicating a unique code path or implementation issue within Adobe's PDF processing libraries.
The technical implementation of this use-after-free vulnerability stems from improper memory management within Adobe's PDF rendering engine. When processing specially crafted PDF documents, the application fails to properly validate memory references after objects have been freed from memory, creating a window where attacker-controlled data can be written to or read from previously freed memory locations. This memory corruption allows adversaries to manipulate program execution flow and potentially inject malicious code into the application's memory space. The vulnerability operates at the core level of PDF processing, where objects such as graphics, fonts, or embedded content are handled, making it particularly insidious as it can be triggered through normal document viewing operations. The flaw typically manifests when the application processes malformed PDF content that causes the system to free memory associated with certain objects while simultaneously attempting to access those same memory locations.
From an operational perspective, this vulnerability creates severe risks for enterprise environments and individual users alike. Attackers can craft malicious PDF files that, when opened in vulnerable versions of Adobe Reader or Acrobat, will trigger the use-after-free condition and subsequently execute arbitrary code on the target system. This capability enables threat actors to perform privilege escalation, establish persistent backdoors, or gain complete system compromise without requiring user interaction beyond opening the malicious document. The attack vector is particularly dangerous in phishing campaigns where users are tricked into opening seemingly legitimate PDF documents containing the malicious payload. Organizations that rely heavily on PDF document sharing, such as financial institutions, government agencies, or legal firms, face significant exposure risks. The vulnerability's presence in multiple product versions and operating systems amplifies the potential attack surface, requiring comprehensive patch management across various platforms and software versions.
Mitigation strategies for CVE-2016-6968 should prioritize immediate patch deployment across all affected Adobe Reader and Acrobat installations. Adobe released security updates for the vulnerable versions, including specific patches for Acrobat and Acrobat Reader DC Classic and Continuous versions. System administrators should implement comprehensive vulnerability management processes that include regular security updates, application whitelisting, and sandboxing mechanisms to contain potential exploitation attempts. Network-level protections such as PDF content filtering and email gateway scanning can help prevent malicious documents from reaching end users. Additionally, implementing the principle of least privilege and maintaining up-to-date antivirus signatures will provide additional defense layers. The vulnerability aligns with CWE-416, which describes the use of freed memory condition, and represents a common pattern in memory safety issues that fall under the ATT&CK technique T1059.1001 for command and scripting interpreter. Organizations should also consider implementing security awareness training to reduce the risk of social engineering attacks that rely on PDF-based delivery mechanisms.