CVE-2011-2100 in Acrobat
Summary
by MITRE
Untrusted search path vulnerability in Adobe Reader and Acrobat 8.x before 8.3, 9.x before 9.4.5, and 10.x before 10.1 on Windows allows local users to gain privileges via a Trojan horse DLL in the current working directory.
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Analysis
by VulDB Data Team • 10/17/2018
The vulnerability identified as CVE-2011-2100 represents a critical untrusted search path issue affecting Adobe Reader and Acrobat versions across multiple release lines including 8.x before 8.3, 9.x before 9.4.5, and 10.x before 10.1 on Windows platforms. This flaw resides in the application's dynamic link library loading mechanism and constitutes a classic privilege escalation vector through malicious code injection. The vulnerability stems from Adobe's failure to properly validate the source and integrity of dynamically loaded libraries, creating an environment where malicious actors can place specially crafted DLL files in the current working directory to execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability exploits the Windows DLL search order mechanism, which follows a specific sequence when resolving dynamic link libraries. When Adobe Reader or Acrobat processes certain file types, it may load DLLs from the current working directory before checking system directories, allowing attackers to place malicious DLLs with the same names as legitimate Adobe components. This behavior directly maps to CWE-427, which describes uncontrolled search path dependencies, and aligns with ATT&CK technique T1068, which covers local privilege escalation through malicious DLL loading. The flaw essentially allows an attacker to manipulate the application's execution flow by pre-positioning malicious libraries in directories that Windows will prioritize during the loading process, bypassing normal security controls and code signing mechanisms.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with the ability to escalate privileges from standard user accounts to system-level access. Local users who interact with vulnerable Adobe applications can leverage this flaw to gain unauthorized system access, potentially leading to complete system compromise. The attack vector is particularly concerning because it requires minimal user interaction beyond opening a malicious file, making it suitable for social engineering campaigns and automated exploitation. This vulnerability also impacts enterprise environments where Adobe Reader is widely deployed, potentially allowing attackers to establish persistent access points within networks. The risk is compounded by the fact that many organizations still maintain older versions of Adobe Reader, creating a substantial attack surface that can be exploited without requiring sophisticated targeting or advanced exploitation techniques.
Mitigation strategies for CVE-2011-2100 should prioritize immediate patching of affected Adobe applications to the latest available versions, as Adobe released security updates addressing this specific vulnerability. Organizations should implement application whitelisting policies that restrict the execution of unsigned or untrusted DLLs, particularly in user directories where attackers might place malicious files. System administrators should also consider implementing strict directory permissions and monitoring for unusual DLL loading patterns through security information and event management systems. The principle of least privilege should be enforced by running Adobe Reader with reduced permissions and avoiding installation in user-writable directories. Additionally, network segmentation and endpoint protection solutions can help detect and prevent exploitation attempts, while regular security audits should verify that no vulnerable versions remain in use within the organization. Organizations should also consider deploying Adobe's recommended security configurations and disabling unnecessary features that might contribute to the attack surface, as this vulnerability demonstrates the critical importance of proper library loading security practices in enterprise software deployment environments.