CVE-2011-5155 in Help
Summary
by MITRE
Untrusted search path vulnerability in Help & Manual 5.5.1 Build 1296 allows local users to gain privileges via a Trojan horse ijl15.dll file in the current working directory, as demonstrated by a directory that contains a .hmxz, .hmxp, .hmskin, .hmx, .hm3, .hpj, .hlp, or .chm file. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 05/25/2025
This vulnerability exists in Help & Manual version 5.5.1 Build 1296 and represents a classic untrusted search path weakness that enables local privilege escalation through malicious dynamic link library injection. The flaw occurs when the application loads the ijl15.dll library from the current working directory without proper validation of the library's source or integrity, creating an opportunity for attackers to place a malicious version of this library in the same directory as the vulnerable application. The vulnerability is particularly concerning because it can be triggered through various file types including .hmxz, .hmxp, .hmskin, .hmx, .hm3, .hpj, .hlp, and .chm files, which are all valid Help & Manual project and documentation formats. This wide range of triggerable file types increases the attack surface and makes exploitation more likely to succeed in real-world scenarios.
The technical implementation of this vulnerability stems from improper library loading practices where the application does not explicitly specify the full path to system libraries or does not verify library authenticity before loading. According to CWE-427, this maps directly to an uncontrolled search path vulnerability where the program searches for libraries in an untrusted location, and the attack vector is consistent with CWE-428 which describes untrusted search path elements. The operating system's dynamic link library loading mechanism prioritizes the current working directory in its search path, making this attack possible without requiring elevated privileges to place files in system directories. This behavior aligns with the ATT&CK technique T1068 which covers "Local Privilege Escalation" through exploitation of system vulnerabilities.
The operational impact of this vulnerability extends beyond simple privilege escalation to potentially allow attackers to execute arbitrary code with elevated privileges. When a local user opens any of the specified file types, the application automatically loads the malicious ijl15.dll from the current working directory, which could contain malicious code designed to escalate privileges, steal credentials, or establish persistence mechanisms. The vulnerability affects all local users who have access to the vulnerable application and can manipulate the current working directory, making it particularly dangerous in shared or multi-user environments where attackers might exploit this through social engineering or by placing malicious files in directories where the application is commonly executed. The attack requires minimal technical expertise and can be automated, making it a significant threat vector for both malicious actors and compromised systems.
Mitigation strategies should focus on addressing the root cause through proper library loading practices and implementing security measures that prevent untrusted code execution. System administrators should ensure that Help & Manual is updated to versions that properly validate library sources and implement explicit library loading paths rather than relying on the default search behavior. The recommended approach includes implementing the principle of least privilege by restricting write access to directories where Help & Manual is executed, and employing application whitelisting solutions to prevent unauthorized DLL loading. Additionally, security configurations should include disabling automatic loading of external libraries and implementing proper file integrity checks. Organizations should also consider deploying monitoring solutions that can detect suspicious DLL loading activities and implement regular security assessments to identify similar vulnerabilities in other applications. The vulnerability demonstrates the importance of secure coding practices and proper library management as outlined in industry standards such as those defined by the CWE and ATT&CK frameworks.