CVE-2017-7853 in oSIP
Summary
by MITRE
In libosip2 in GNU oSIP 5.0.0, a malformed SIP message can lead to a heap buffer overflow in the msg_osip_body_parse() function defined in osipparser2/osip_message_parse.c, resulting in a remote DoS.
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Analysis
by VulDB Data Team • 08/30/2020
The vulnerability identified as CVE-2017-7853 resides within the libosip2 library component of GNU oSIP version 5.0.0, specifically manifesting in the msg_osip_body_parse() function located in osipparser2/osip_message_parse.c. This heap buffer overflow represents a critical security flaw that can be exploited remotely, potentially leading to denial of service conditions. The vulnerability stems from insufficient input validation during the parsing of SIP (Session Initiation Protocol) messages, where malformed data can trigger unpredictable memory corruption patterns. The affected library serves as a core component for SIP message handling in numerous communication applications and operating systems, making this vulnerability particularly dangerous as it can impact a wide range of services relying on SIP protocol implementations.
The technical exploitation of this vulnerability occurs when a maliciously crafted SIP message is processed by the affected software. The msg_osip_body_parse() function fails to properly validate buffer boundaries during message parsing operations, allowing an attacker to craft input data that exceeds allocated memory space. This overflow condition manifests as heap corruption, which can result in application crashes, memory corruption, or potentially more severe consequences depending on the execution environment. The vulnerability specifically affects the parsing of SIP message bodies where the parser does not adequately check for buffer overflows during the processing of malformed input data. This type of flaw falls under the Common Weakness Enumeration category CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation in network protocol parsers.
The operational impact of CVE-2017-7853 extends beyond simple service disruption to potentially compromise the stability and availability of communication services. Remote attackers can leverage this vulnerability to perform denial of service attacks against SIP servers, clients, or gateways that utilize the vulnerable libosip2 library. The attack surface includes any system that processes SIP messages, including VoIP servers, PBX systems, SIP proxies, and communication applications. When exploited successfully, the heap buffer overflow can cause applications to crash immediately, leading to service unavailability for legitimate users. In some scenarios, the memory corruption could potentially be exploited further for arbitrary code execution, though the primary impact documented is remote denial of service. The vulnerability's remote nature means that attackers do not need local access to the target system, making it particularly dangerous for publicly accessible SIP services.
Mitigation strategies for CVE-2017-7853 primarily focus on updating to patched versions of the GNU oSIP library where the buffer overflow has been addressed through proper input validation and memory boundary checks. System administrators should prioritize updating their implementations to versions that contain the fix for the msg_osip_body_parse() function, ensuring that all SIP-related applications are running with secure library versions. Network-level protections such as SIP message filtering and rate limiting can provide additional defensive measures by detecting and blocking malformed SIP traffic before it reaches vulnerable applications. Implementing proper input sanitization and validation within application code that interfaces with libosip2 can also help reduce the attack surface. Organizations should also consider monitoring for unusual SIP traffic patterns that might indicate exploitation attempts and maintain updated threat intelligence feeds to identify potential variants of this attack vector. The vulnerability demonstrates the importance of robust input validation in network protocol implementations and aligns with ATT&CK technique T1203, which covers legitimate credentials and network protocols for remote access, emphasizing the need for secure parsing of network communications.