CVE-2017-10893 in Public Certification Service for Individuals
Summary
by MITRE
Untrusted search path vulnerability in The Public Certification Service for Individuals "The JPKI user's software" Ver3.1 and earlier allows an attacker to gain privileges via a Trojan horse DLL in an unspecified directory.
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Analysis
by VulDB Data Team • 12/12/2019
The vulnerability identified as CVE-2017-10893 represents a critical untrusted search path issue within The Public Certification Service for Individuals JPKI user's software version 3.1 and earlier. This flaw resides in the software's dynamic link library loading mechanism, where the application fails to properly validate the source and integrity of dynamically loaded components. The vulnerability stems from the software's improper handling of the Windows DLL search order, which allows an attacker to place a malicious Trojan horse DLL in a directory that the application will automatically load before checking system directories. This weakness directly maps to CWE-427, which describes uncontrolled search path vulnerabilities where applications search directories in an insecure order, and aligns with ATT&CK technique T1068, which covers privilege escalation through the exploitation of application vulnerabilities. The affected software operates under the assumption that all DLLs loaded from the application's directory are legitimate, creating a window of opportunity for attackers to execute arbitrary code with the privileges of the targeted user.
The operational impact of this vulnerability extends beyond simple code execution to encompass full privilege escalation capabilities within the context of the user's session. When an attacker successfully places a malicious DLL in the application's search path, the software will load and execute the malicious code without proper validation or authentication. This creates a persistent threat vector that can be leveraged to establish backdoors, exfiltrate sensitive data, or perform further exploitation within the compromised system. The vulnerability is particularly dangerous because it operates silently without user intervention, and the malicious DLL can be designed to perform various malicious activities including credential harvesting, system reconnaissance, or establishing persistent access. The attack requires minimal privileges to execute initially, as the malicious DLL only needs to be placed in the appropriate directory, making it an attractive target for attackers seeking to escalate their access within a compromised environment.
Mitigation strategies for CVE-2017-10893 must address both the immediate vulnerability and implement broader security controls to prevent similar issues in the future. The most effective immediate fix involves updating to a patched version of the JPKI user's software where the application properly implements secure DLL loading practices, such as using LoadLibraryEx with the LOAD_WITH_ALTERED_SEARCH_PATH flag or explicitly specifying full paths to DLLs. Organizations should also implement application whitelisting solutions that restrict which DLLs can be loaded by the application, effectively blocking unauthorized code execution. Additionally, system administrators should conduct thorough directory permission reviews to ensure that write access to application directories is restricted to authorized users only. The implementation of security controls such as Windows Defender Application Control or similar technologies can further prevent the execution of unauthorized DLLs, while regular security audits should verify that no malicious DLLs have been placed in the application's search path. These measures align with the principle of least privilege and help protect against similar vulnerabilities categorized under CWE-427 and the broader category of privilege escalation attacks documented in the MITRE ATT&CK framework.