CVE-2023-28097 in OpenSIPS
Summary
by MITRE • 03/16/2023
OpenSIPS is a Session Initiation Protocol (SIP) server implementation. Prior to versions 3.1.9 and 3.2.6, a malformed SIP message containing a large _Content-Length_ value and a specially crafted Request-URI causes a segmentation fault in OpenSIPS. This issue occurs when a large amount of shared memory using the `-m` flag was allocated to OpenSIPS, such as 10 GB of RAM. On the test system, this issue occurred when shared memory was set to `2362` or higher. This issue is fixed in versions 3.1.9 and 3.2.6. The only workaround is to guarantee that the Content-Length value of input messages is never larger than `2147483647`.
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Analysis
by VulDB Data Team • 03/16/2023
The vulnerability CVE-2023-28097 affects OpenSIPS, a widely-used Session Initiation Protocol server implementation that facilitates VoIP communications and real-time media sessions. This critical flaw resides in the message parsing mechanism of the SIP server, specifically when handling malformed SIP requests that contain excessive Content-Length values. The vulnerability represents a classic buffer overflow condition that can lead to system instability and potential service disruption. The issue manifests when OpenSIPS processes SIP messages with oversized Content-Length headers combined with specially crafted Request-URI fields, creating a scenario where the application attempts to allocate memory beyond its intended boundaries. This type of vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and falls under the broader category of memory safety issues that have historically plagued network services.
The technical exploitation of this vulnerability requires careful crafting of SIP messages that exceed normal parameter limits while leveraging the shared memory allocation mechanism. When OpenSIPS is configured with substantial shared memory using the `-m` flag, particularly values of 2362 or higher, the application becomes susceptible to segmentation faults during message processing. The specific threshold of 2362 appears to correspond to the memory allocation boundaries where the overflow condition manifests. The segmentation fault occurs because the server's internal parsing logic fails to properly validate the Content-Length field against system limits, causing memory allocation requests that exceed available resources or trigger invalid memory access patterns. This vulnerability directly impacts the server's stability and availability, potentially allowing attackers to cause denial of service conditions that disrupt legitimate communication services.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential system compromise and communication interruption in environments relying on OpenSIPS for VoIP infrastructure. Organizations using affected versions may experience unexpected server crashes, leading to loss of SIP signaling capabilities and disruption of voice and video communications. The vulnerability is particularly concerning in production environments where OpenSIPS serves as a critical component of telecommunication infrastructure, as the segmentation fault can occur without proper error handling or logging mechanisms. The attack surface includes any system processing SIP traffic through vulnerable OpenSIPS installations, making it a significant concern for network administrators managing VoIP systems, unified communications platforms, and real-time communication services.
Mitigation strategies for CVE-2023-28097 focus on both immediate protective measures and long-term architectural improvements. The primary solution involves upgrading to OpenSIPS versions 3.1.9 or 3.2.6, which contain the necessary code fixes to properly validate Content-Length values and prevent memory allocation overflows. Organizations without immediate upgrade capabilities must implement the workaround of enforcing Content-Length limits below 2147483647, effectively preventing the triggering condition. Additional protective measures include implementing network-level filtering to detect and block malformed SIP messages, deploying intrusion detection systems specifically configured to monitor for SIP-based attacks, and establishing robust monitoring procedures to detect system instability or unexpected restarts. Security teams should also consider implementing rate limiting mechanisms for SIP message processing and conducting regular vulnerability assessments to identify other potential memory safety issues in the SIP stack. The vulnerability demonstrates the importance of proper input validation in network services and aligns with ATT&CK technique T1499.004, which covers network denial of service attacks through memory corruption.