CVE-2019-17099 in Endpoint Security Tools
Summary
by MITRE
An Untrusted Search Path vulnerability in EPSecurityService.exe as used in Bitdefender Endpoint Security Tools versions prior to 6.6.11.163 allows an attacker to load an arbitrary DLL file from the search path. This issue affects: Bitdefender EPSecurityService.exe versions prior to 6.6.11.163.
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Analysis
by VulDB Data Team • 03/26/2024
The vulnerability identified as CVE-2019-17099 represents a critical untrusted search path weakness within the EPSecurityService.exe component of Bitdefender Endpoint Security Tools. This flaw exists in versions prior to 6.6.11.163 and creates a significant security risk by allowing attackers to manipulate the dynamic link library loading process. The issue stems from the service's improper handling of library search paths, which enables malicious actors to place specially crafted DLL files in locations that the service will automatically load without proper validation. This type of vulnerability falls under CWE-426, which specifically addresses the execution of untrusted code due to insecure search path handling, making it a direct descendant of the well-known insecure library loading patterns that have plagued numerous security applications.
The technical exploitation of this vulnerability occurs when an attacker places a malicious DLL file in a directory that appears earlier in the system's search path than the legitimate Bitdefender libraries. When EPSecurityService.exe executes and attempts to load required dependencies, it will first search the directories specified in the PATH environment variable or other configured search locations. If the attacker-controlled directory is prioritized in this search order, the service will load and execute the malicious DLL instead of the intended legitimate library. This behavior represents a classic privilege escalation vector since the EPSecurityService.exe typically runs with elevated privileges, potentially allowing attackers to execute arbitrary code with system-level permissions. The vulnerability's impact is further exacerbated by the fact that the service runs continuously and maintains persistent access to the system, providing attackers with a stable execution environment for their malicious payloads.
The operational implications of this vulnerability extend beyond simple code execution, as it can serve as a foundation for more sophisticated attack vectors within enterprise environments. Organizations utilizing affected Bitdefender versions face the risk of persistent backdoor installation, privilege escalation, and lateral movement within their networks. The attack surface becomes particularly concerning in enterprise settings where endpoint security tools are often granted extensive system privileges to perform their protective functions. This vulnerability demonstrates how security tools themselves can become attack vectors when not properly configured or patched, creating a paradoxical situation where the very software designed to protect systems becomes a potential entry point for adversaries. The issue affects organizations that have not yet updated to the patched version 6.6.11.163, leaving them exposed to potential exploitation by threat actors who may be actively targeting this specific flaw.
Mitigation strategies for CVE-2019-17099 should prioritize immediate patch deployment to version 6.6.11.163 or later, as provided by Bitdefender. System administrators should also implement additional protective measures including the use of secure library loading practices, such as explicitly specifying library paths and using the LoadLibraryEx function with the LOAD_WITH_ALTERED_SEARCH_PATH flag to prevent unintended DLL loading. Organizations should conduct comprehensive vulnerability assessments to identify any other services or applications that may be susceptible to similar untrusted search path vulnerabilities. The ATT&CK framework categorizes this type of vulnerability under T1055 - Process Injection and T1574 - Hijacking, making it relevant to both privilege escalation and persistence tactics. Security monitoring should be enhanced to detect unusual DLL loading patterns, particularly in system services that run with elevated privileges. Network segmentation and privilege separation should also be considered as additional defensive measures to limit the potential impact of successful exploitation attempts.