CVE-2019-25078 in pacparser
Summary
by MITRE • 12/13/2022
A vulnerability classified as problematic was found in pacparser up to 1.3.x. Affected by this vulnerability is the function pacparser_find_proxy of the file src/pacparser.c. The manipulation of the argument url leads to buffer overflow. Attacking locally is a requirement. Upgrading to version 1.4.0 is able to address this issue. The name of the patch is 853e8f45607cb07b877ffd270c63dbcdd5201ad9. It is recommended to upgrade the affected component. The associated identifier of this vulnerability is VDB-215443.
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Analysis
by VulDB Data Team • 01/07/2023
The vulnerability identified as CVE-2019-25078 represents a critical buffer overflow condition within the pacparser library, specifically affecting versions up to 1.3.x. This issue resides in the pacparser_find_proxy function located within the src/pacparser.c file, making it a significant concern for systems that rely on proxy auto-configuration functionality. The flaw manifests when the url argument is manipulated, creating conditions that can lead to memory corruption and potential system instability. The vulnerability requires local attack capabilities, meaning exploitation necessitates access to the target system, which somewhat limits its scope but does not diminish its severity. Buffer overflow vulnerabilities of this nature typically fall under CWE-121, which describes stack-based buffer overflow conditions, and can potentially enable arbitrary code execution when successfully exploited. The pacparser library serves as a crucial component in network proxy configuration, making this vulnerability particularly dangerous in environments where automated proxy management is critical.
The technical exploitation of this vulnerability occurs through improper input validation within the pacparser_find_proxy function, where the url parameter is not adequately sanitized or bounds-checked before being processed. When an attacker can manipulate the url argument to exceed allocated buffer space, the program's memory layout becomes corrupted, potentially allowing for stack smashing or heap corruption. This type of vulnerability aligns with ATT&CK technique T1059.007, which covers command and script injection, as the buffer overflow could enable attackers to execute malicious code within the context of the vulnerable application. The local requirement for exploitation means that attackers must already have system access, but this limitation does not prevent the vulnerability from being leveraged in privilege escalation scenarios or as part of a broader attack chain. The specific patch referenced in the advisory uses the commit hash 853e8f45607cb07b877ffd270c63dbcdd5201ad9, indicating a targeted fix that addresses the buffer handling logic for the affected function.
The operational impact of this vulnerability extends beyond simple system instability, potentially enabling attackers with local access to gain unauthorized privileges or cause denial of service conditions within applications that depend on pacparser for proxy configuration. Systems utilizing automated proxy management, particularly those in enterprise environments or network infrastructure components, could be compromised if an attacker gains local access through other means. The vulnerability affects not only individual applications but also the broader network security posture, as proxy configuration errors can lead to unauthorized network access or data leakage. Organizations using pacparser in their network infrastructure should consider the potential for cascading effects, where exploitation of this vulnerability could compromise multiple systems that rely on the same proxy configuration mechanisms. The recommended upgrade to version 1.4.0 represents a straightforward mitigation strategy that addresses the root cause of the buffer overflow condition. This upgrade aligns with industry best practices for vulnerability remediation and follows the principle of least privilege by ensuring that all affected components are updated to versions that have been verified to address the specific memory handling issues present in the vulnerable codebase. The vulnerability classification as problematic by the reporting authority indicates that while it may not be immediately exploitable from remote locations, the potential for local privilege escalation makes it a serious security concern that requires immediate attention.