CVE-2017-2233 in PDF Digital Signature Plugin
Summary
by MITRE
Untrusted search path vulnerability in Installer of PDF Digital Signature Plugin (G2.30) and earlier, distributed till June 29, 2017 allows an attacker to gain privileges via a Trojan horse DLL in an unspecified directory.
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Analysis
by VulDB Data Team • 10/24/2019
The vulnerability identified as CVE-2017-2233 represents a critical untrusted search path weakness within the Installer component of the PDF Digital Signature Plugin version G2.30 and earlier. This flaw affects installations distributed through June 29, 2017, creating a significant security risk that adversaries can exploit to elevate privileges through malicious DLL injection techniques. The vulnerability stems from the installer's failure to properly validate or sanitize the search path used to locate required dynamic link libraries during the installation process, allowing attackers to place malicious code in directories that are searched before legitimate system locations.
The technical implementation of this vulnerability aligns with CWE-426, which describes untrusted search path conditions where programs search for files in directories that can be manipulated by attackers. The PDF Digital Signature Plugin installer operates under the assumption that all DLLs in its search path are legitimate and trustworthy, failing to implement proper validation mechanisms to verify the authenticity and integrity of loaded modules. This design flaw creates a privilege escalation vector where an attacker can position a Trojan horse DLL in a directory that gets searched before system directories, causing the installer to load and execute malicious code with elevated privileges typically reserved for system-level operations. The vulnerability specifically affects the installation process where the plugin's installer attempts to load dependent libraries, making it particularly dangerous during system-wide installations or updates.
The operational impact of CVE-2017-2233 extends beyond simple privilege escalation to encompass potential system compromise and data exfiltration capabilities. Attackers leveraging this vulnerability can execute arbitrary code with elevated privileges, potentially leading to complete system takeover, persistence mechanisms installation, and access to sensitive information stored within the system. The timing of the vulnerability's exploitation becomes critical since the flaw exists in versions distributed until June 29, 2017, suggesting that systems running these older versions remain at risk if not properly updated or patched. This vulnerability also demonstrates the broader risk associated with legacy software components and the importance of proper input validation and secure coding practices in installation processes, particularly those involving dynamic library loading mechanisms.
Mitigation strategies for CVE-2017-2233 should prioritize immediate patching of affected PDF Digital Signature Plugin versions to the latest available releases that address the untrusted search path vulnerability. System administrators should implement strict directory permissions and access controls to prevent unauthorized DLL placement in installation directories, while also conducting thorough security audits of system paths used by legacy applications. The implementation of application whitelisting policies and monitoring for suspicious DLL loading activities can help detect potential exploitation attempts. Additionally, organizations should consider implementing security measures aligned with the ATT&CK framework's privilege escalation techniques, particularly focusing on the T1068 entry point related to local privilege escalation through DLL injection. Regular security assessments of third-party software installation processes and the enforcement of secure coding practices that prevent untrusted search path conditions should be standard operational procedures to prevent similar vulnerabilities from emerging in future software deployments.