CVE-2016-6993 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-2016-6968, CVE-2016-6969, CVE-2016-6971, CVE-2016-6979, and CVE-2016-6988.
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Analysis
by VulDB Data Team • 10/18/2024
The vulnerability identified as CVE-2016-6993 represents a critical use-after-free flaw in Adobe Reader and Acrobat products across multiple versions, specifically affecting Windows and macOS platforms. This type of vulnerability occurs when a program continues to reference memory locations after they have been freed, creating opportunities for malicious actors to manipulate memory contents and potentially execute arbitrary code. The issue affects Adobe Reader versions prior to 11.0.18 and Acrobat versions before 11.0.18, alongside various DC Classic and DC Continuous versions with specific build numbers. Unlike other vulnerabilities in the same advisory, CVE-2016-6993 operates through distinct attack vectors that have been carefully isolated from the previously mentioned CVE identifiers, indicating a unique exploitation pathway.
This use-after-free vulnerability falls under the CWE-416 category, which specifically addresses the use of freed memory conditions in software applications. The technical implementation involves memory management errors where the application fails to properly track memory references, allowing attackers to manipulate freed memory blocks. The vulnerability's exploitation requires an attacker to craft malicious content that triggers the specific memory access patterns leading to the use-after-free condition. The attack typically involves manipulating PDF documents or other content processed by Adobe Reader to cause the application to reference already freed memory segments. This creates a scenario where attackers can overwrite memory contents with malicious code or manipulate program execution flow to achieve code execution privileges.
The operational impact of CVE-2016-6993 extends beyond simple privilege escalation, as it provides attackers with complete system compromise capabilities when successfully exploited. The vulnerability enables remote code execution without requiring user interaction in many scenarios, making it particularly dangerous for enterprise environments where Adobe Reader is commonly used for document processing. The attack surface includes any system running affected Adobe products, with the risk being heightened due to the widespread adoption of these applications across various industries. Organizations using legacy versions of Adobe Reader and Acrobat face significant exposure to this vulnerability, as the exploitation can lead to full system compromise, data exfiltration, and persistence mechanisms. The vulnerability's presence in both classic and continuous DC versions indicates that even organizations that have upgraded to newer release streams may remain vulnerable if they haven't reached the specific patched versions.
Mitigation strategies for CVE-2016-6993 require immediate patch deployment across all affected systems, with priority given to enterprise environments where the risk is highest. Adobe has released security updates for all affected versions, and system administrators should implement these patches as a critical security measure. Additional protective measures include implementing application whitelisting policies, configuring sandboxing environments for PDF processing, and employing network-based security controls such as intrusion detection systems to monitor for exploitation attempts. The vulnerability's nature makes it particularly susceptible to automated exploitation, so organizations should also consider deploying endpoint protection solutions that can detect and prevent memory corruption attacks. Security teams should also conduct comprehensive vulnerability assessments to identify all systems running affected Adobe software versions and implement remediation plans that include both immediate patching and long-term security hardening measures. The ATT&CK framework categorizes this vulnerability under the T1059.007 technique for command and scripting interpreter, as successful exploitation would likely enable attackers to execute malicious commands through compromised Adobe processes.