CVE-2016-1091 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-2016-6944, 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, CVE-2016-6988, and CVE-2016-6993.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/23/2022
This use-after-free vulnerability in Adobe Reader and Acrobat products represents a critical memory safety flaw that enables remote code execution attacks. The vulnerability exists in the handling of specific objects within the software's memory management system, where freed memory regions are accessed after being deallocated. This particular flaw affects multiple versions of Adobe's document processing software across both Windows and macOS operating systems, with specific affected versions including Adobe Reader and Acrobat before 11.0.18, and various DC Classic and DC Continuous releases before their respective patch levels. The vulnerability is distinct from several other related issues documented in the same year, indicating a unique code path that requires separate remediation approaches.
The technical implementation of this vulnerability involves a classic use-after-free condition where an attacker can manipulate the application's memory management to cause the software to access memory that has already been freed and potentially reallocated. This type of vulnerability falls under CWE-416, which specifically addresses the use of freed memory conditions in software applications. When exploited, the attacker can craft malicious PDF documents that trigger the vulnerable code path, leading to memory corruption that can be leveraged to execute arbitrary code with the privileges of the affected application. The attack vector typically involves crafting a specially formatted PDF file that, when opened by the vulnerable software, causes the application to access freed memory locations and redirect execution flow to attacker-controlled code.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete system compromise capabilities when successful. Since Adobe Reader and Acrobat are widely deployed across enterprise environments, the potential for widespread exploitation increases significantly. The vulnerability can be exploited through social engineering campaigns where users are tricked into opening malicious PDF attachments, making it particularly dangerous in targeted attack scenarios. Organizations running affected versions of Adobe software face substantial risk of data breaches, system compromise, and potential lateral movement within their networks. The vulnerability's presence in both classic and continuous delivery versions of Adobe Acrobat indicates a systemic issue that required patching across multiple software delivery channels and update mechanisms.
Mitigation strategies for this vulnerability primarily focus on immediate patch deployment and application of Adobe's security updates. Organizations should prioritize updating to Adobe Acrobat and Reader versions 11.0.18, 15.006.30243, and 15.020.20039 respectively, which contain the necessary fixes for this memory safety issue. Additionally, implementing PDF sandboxing features and restricting user privileges when opening PDF files can provide defense-in-depth measures. Network-based protections such as PDF content filtering and email security gateways can help prevent exploitation attempts by blocking malicious PDF attachments before they reach end users. From an ATT&CK framework perspective, this vulnerability maps to techniques involving exploitation of known vulnerabilities and privilege escalation, specifically leveraging the T1190 (Exploit Public-Facing Application) and T1068 (Exploitation for Privilege Escalation) tactics. Security teams should also consider implementing application whitelisting policies to restrict execution of untrusted PDF files and monitor for suspicious process behavior that may indicate exploitation attempts.