CVE-2019-0065 in Junos
Summary
by MITRE
On MX Series, when the SIP ALG is enabled, receipt of a certain malformed SIP packet may crash the MS-PIC component on MS-MIC or MS-MPC. By continuously sending a crafted SIP packet, an attacker can repeatedly bring down MS-PIC on MS-MIC/MS-MPC causing a sustained Denial of Service. This issue affects Juniper Networks Junos OS on MX Series: 16.1 versions prior to 16.1R7-S5; 16.2 versions prior to 16.2R2-S11; 17.1 versions prior to 17.1R3; 17.2 versions prior to 17.2R3-S3; 17.3 versions prior to 17.3R3-S6 ; 17.4 versions prior to 17.4R2-S8, 17.4R3; 18.1 versions prior to 18.1R3-S3; 18.2 versions prior to 18.2R3; 18.3 versions prior to 18.3R2; 18.4 versions prior to 18.4R2.
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Analysis
by VulDB Data Team • 01/05/2024
This vulnerability represents a critical denial of service weakness in Juniper Networks MX Series routers where the Session Initiation Protocol Application Level Gateway (SIP ALG) functionality creates a path for remote attackers to disrupt network operations through carefully crafted malformed packets. The flaw specifically targets the MS-PIC component residing on MS-MIC or MS-MPC hardware modules, which serves as the primary processing unit for packet handling and network services. When a malformed SIP packet is received with the SIP ALG enabled, the system experiences a crash in the MS-PIC component, effectively removing the router's ability to process network traffic through that specific hardware module. The vulnerability stems from insufficient input validation and error handling within the SIP ALG implementation, allowing attackers to exploit a buffer overflow or memory corruption condition that leads to system instability.
The technical exploitation of this vulnerability follows a straightforward but effective methodology where an attacker continuously sends specifically crafted SIP packets designed to trigger the memory corruption within the MS-PIC component. This approach leverages the fundamental design flaw in how the system processes SIP protocol packets when ALG functionality is active, creating a sustained denial of service condition that can persist as long as the malicious traffic continues. The impact extends beyond simple service disruption to potentially compromise the entire network infrastructure since the MS-PIC component is essential for packet forwarding and network service delivery. This vulnerability directly maps to CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of how application level gateways can introduce security weaknesses when they fail to properly validate input data.
The operational impact of CVE-2019-0065 is severe and multifaceted, affecting enterprise and service provider networks that rely on Juniper MX Series routers for critical communications infrastructure. Network availability is compromised as the MS-PIC component becomes unavailable, leading to complete disruption of services that depend on the affected hardware modules. The sustained nature of the denial of service means that network administrators cannot simply restart the affected components, as the attack continues to maintain system instability. This vulnerability particularly affects organizations using older Junos OS versions where the SIP ALG feature is enabled, creating a window of opportunity for attackers to systematically degrade network performance and availability. The attack vector requires minimal sophistication but maximum effectiveness, making it particularly dangerous in environments where SIP services are commonly used for voice over IP communications.
Organizations affected by this vulnerability should immediately implement mitigation strategies focusing on patch management and configuration changes to prevent exploitation. The recommended approach involves upgrading to the patched versions of Junos OS specified in the advisory, which contain corrected input validation routines for SIP packet processing. Network administrators should also consider disabling the SIP ALG functionality when it is not required, as this removes the attack surface entirely. Additionally, implementing network segmentation and access control measures can help limit the impact of successful exploitation attempts by restricting which systems can send SIP packets to affected routers. From a defensive perspective, this vulnerability highlights the importance of proper protocol handling and input validation in network security appliances, aligning with ATT&CK technique T1499.002 for network disruption attacks and emphasizing the need for robust application level security controls in enterprise network infrastructure.