CVE-2023-28096 in OpenSIPS
Summary
by MITRE • 03/16/2023
OpenSIPS, a Session Initiation Protocol (SIP) server implementation, has a memory leak starting in the 2.3 branch and priot to versions 3.1.8 and 3.2.5. The memory leak was detected in the function `parse_mi_request` while performing coverage-guided fuzzing. This issue can be reproduced by sending multiple requests of the form `{"jsonrpc": "2.0","method": "log_le`. This malformed message was tested against an instance of OpenSIPS via FIFO transport layer and was found to increase the memory consumption over time. To abuse this memory leak, attackers need to reach the management interface (MI) which typically should only be exposed on trusted interfaces. In cases where the MI is exposed to the internet without authentication, abuse of this issue will lead to memory exhaustion which may affect the underlying system’s availability. No authentication is typically required to reproduce this issue. On the other hand, memory leaks may occur in other areas of OpenSIPS where the cJSON library is used for parsing JSON objects. The issue has been fixed in versions 3.1.8 and 3.2.5.
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Analysis
by VulDB Data Team • 04/08/2023
The vulnerability identified as CVE-2023-28096 represents a critical memory leak issue within OpenSIPS, a widely deployed Session Initiation Protocol server implementation that facilitates VoIP communications. This memory leak manifests in the parse_mi_request function when processing specific JSON-RPC requests, creating a persistent resource consumption problem that can lead to system instability and potential denial of service conditions. The vulnerability affects OpenSIPS versions starting from the 2.3 branch through prior to versions 3.1.8 and 3.2.5, making it a long-standing issue that has impacted numerous deployments. The flaw was discovered through coverage-guided fuzzing techniques, highlighting the importance of systematic security testing in identifying resource management vulnerabilities that may not be apparent during normal operation. The specific exploit pattern involves sending multiple malformed JSON-RPC requests with the prefix {"jsonrpc": "2.0","method": "log_le which triggers the memory leak mechanism within the management interface processing code.
The technical exploitation of this vulnerability leverages the cJSON library's JSON parsing capabilities within OpenSIPS, where improper memory deallocation occurs during the processing of malformed requests. The parse_mi_request function fails to properly release allocated memory resources when handling the specific JSON structure, leading to gradual memory consumption over time. This memory leak is particularly concerning because it operates through the management interface transport layer, typically designed for administrative access but often misconfigured to be accessible from untrusted networks. The vulnerability's impact extends beyond simple resource waste as it can be triggered without authentication requirements, making it accessible to any attacker who can reach the management interface. The memory consumption pattern increases progressively with each malformed request, creating a predictable degradation that can be easily monitored and exploited for availability attacks.
The operational implications of this memory leak vulnerability are severe, particularly when the management interface is exposed to internet-facing networks without proper authentication controls. Attackers can systematically consume system memory resources through repeated malformed requests, eventually leading to complete memory exhaustion and service disruption. This scenario directly aligns with attack patterns described in the MITRE ATT&CK framework under the resource exhaustion category, where adversaries target system resources to deny service to legitimate users. The vulnerability's presence in the cJSON library usage patterns across OpenSIPS indicates potential for similar issues in other components that rely on the same JSON parsing mechanisms, suggesting a broader impact on the application's memory management practices. The issue's classification under CWE-401 indicates a classic memory leak problem where allocated memory is not properly freed, creating persistent resource consumption that can be amplified through repeated exploitation attempts.
Mitigation strategies for CVE-2023-28096 require immediate deployment of patched versions 3.1.8 and 3.2.5, which contain the necessary fixes to properly handle memory deallocation in the parse_mi_request function. Network administrators should implement strict access controls to limit management interface exposure, ensuring that the MI layer is only accessible from trusted network segments through proper firewall rules and authentication mechanisms. The vulnerability's nature suggests that organizations should conduct thorough security assessments of their OpenSIPS deployments to identify any potential exposure of management interfaces to untrusted networks. Additionally, monitoring systems should be implemented to track memory consumption patterns on SIP servers, enabling early detection of potential exploitation attempts. The fix addresses the root cause by ensuring proper memory cleanup in JSON parsing operations, aligning with industry best practices for secure memory management and preventing similar issues in the cJSON library integration. Organizations should also consider implementing rate limiting and request validation mechanisms to further protect against abuse of the management interface while maintaining operational security posture against resource exhaustion attacks.