CVE-2020-5137 in SonicOS
Summary
by MITRE • 10/12/2020
A buffer overflow vulnerability in SonicOS allows a remote unauthenticated attacker to cause Denial of Service (DoS) on the firewall SSLVPN service and leads to firewall crash. This vulnerability affected SonicOS Gen 5 version 5.9.1.7, 5.9.1.13, Gen 6 version 6.5.4.7, 6.5.1.12, 6.0.5.3, SonicOSv 6.5.4.v and Gen 7 version 7.0.0.0.
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Analysis
by VulDB Data Team • 11/18/2020
The buffer overflow vulnerability identified as CVE-2020-5137 represents a critical security flaw within SonicOS firewall implementations that specifically targets the SSLVPN service functionality. This vulnerability manifests as a remote code execution risk that can be exploited by unauthenticated attackers to induce a denial of service condition, ultimately resulting in complete firewall system crashes. The flaw affects multiple generations of SonicOS software including versions 5.9.1.7 and 5.9.1.13 from Gen 5, versions 6.5.4.7, 6.5.1.12, and 6.0.5.3 from Gen 6, SonicOSv 6.5.4.v, and Gen 7 version 7.0.0.0, demonstrating the widespread nature of this vulnerability across different firmware releases. The technical nature of this vulnerability aligns with CWE-121, which describes buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations, potentially leading to arbitrary code execution or system instability.
The operational impact of CVE-2020-5137 extends far beyond simple service disruption as it compromises the fundamental integrity of network security infrastructure. When exploited, the buffer overflow causes the SSLVPN service to crash, effectively cutting off legitimate remote access capabilities for authorized users while simultaneously leaving the firewall vulnerable to further exploitation attempts. This creates a cascading effect where network administrators lose critical remote management capabilities, potentially forcing them to rely on physical access or alternative recovery mechanisms. The vulnerability's remote nature means that attackers can exploit it from anywhere on the internet without requiring prior authentication credentials, making it particularly dangerous for organizations that depend on SSLVPN services for remote workforce connectivity. According to ATT&CK framework category T1499, this vulnerability enables adversaries to disrupt services and cause system unavailability, representing a significant threat to business continuity and network security operations.
Organizations affected by this vulnerability must implement immediate mitigation strategies to protect their network infrastructure from exploitation attempts. The primary recommended action involves applying the latest firmware updates provided by SonicWall, which contain patches specifically designed to address the buffer overflow conditions in the SSLVPN service implementation. Network segmentation and access control measures should be enhanced to limit exposure of vulnerable systems to external threats, while monitoring systems should be configured to detect unusual traffic patterns that may indicate exploitation attempts. Security teams should also conduct comprehensive vulnerability assessments to identify all instances of affected SonicOS versions across their network infrastructure and prioritize remediation efforts based on risk exposure. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches and implementing robust security monitoring procedures to detect and respond to exploitation attempts before they can cause significant damage to network operations.