CVE-2017-16875 in PJSIP
Summary
by MITRE
An issue was discovered in Teluu pjproject (pjlib and pjlib-util) in PJSIP before 2.7.1. The ioqueue component may issue a double key unregistration after an attacker initiates a socket connection with specific settings and sequences. Such double key unregistration will trigger an integer overflow, which may cause ioqueue backends to reject future key registrations.
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Analysis
by VulDB Data Team • 01/11/2023
The vulnerability identified as CVE-2017-16875 represents a critical flaw in the Teluu pjproject library, specifically within the ioqueue component that manages I/O operations for network connections. This issue affects PJSIP versions prior to 2.7.1 and stems from improper handling of socket connection sequences that can be exploited by remote attackers to manipulate the ioqueue backend functionality. The vulnerability is particularly concerning as it operates at a foundational level of network I/O management within the pjproject framework, which is widely used in VoIP applications and multimedia communication systems.
The technical implementation of this vulnerability involves a specific sequence of socket connection operations that triggers a double key unregistration within the ioqueue subsystem. When an attacker successfully establishes a socket connection with carefully crafted parameters and timing, the ioqueue component processes these operations in a manner that leads to the same key being unregistered twice. This double unregistration event subsequently causes an integer overflow condition within the backend management structures, creating a cascading effect that fundamentally disrupts the ioqueue's ability to properly register new keys. The integer overflow occurs due to the manipulation of internal counters or indices that track registered keys, causing them to wrap around to invalid values.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it fundamentally compromises the ioqueue backend's registration capabilities. Once the integer overflow occurs, the system enters a state where future key registrations are systematically rejected, effectively breaking the I/O operation management for the affected application. This can lead to complete disruption of network communication services that depend on pjproject for their core functionality, particularly in VoIP implementations where real-time communication is essential. The vulnerability affects systems that rely on the ioqueue component for managing multiple concurrent socket connections, making it particularly dangerous in high-traffic environments where connection management is critical.
Security implications of this vulnerability align with CWE-190, which categorizes integer overflow conditions, and can be mapped to ATT&CK technique T1499.1 for network denial of service attacks. The attack vector requires remote exploitation through carefully orchestrated socket connection sequences, making it a sophisticated network-based threat that can be leveraged to disrupt critical communication services. Organizations using pjproject versions prior to 2.7.1 should immediately implement mitigations including upgrading to patched versions, implementing network-level firewalls to restrict suspicious connection patterns, and monitoring for abnormal socket registration behaviors that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation and state management in network I/O subsystems, highlighting how seemingly minor implementation flaws can lead to significant operational disruptions in critical communication infrastructure.