CVE-2018-5299 in Pulse Connect Secure
Summary
by MITRE
A stack-based Buffer Overflow Vulnerability exists in the web server in Pulse Secure Pulse Connect Secure (PCS) before 8.3R4 and Pulse Policy Secure (PPS) before 5.4R4, leading to memory corruption and possibly remote code execution.
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Analysis
by VulDB Data Team • 12/23/2019
The vulnerability identified as CVE-2018-5299 represents a critical stack-based buffer overflow affecting Pulse Secure's Pulse Connect Secure and Pulse Policy Secure appliances. This flaw resides within the web server component of these security products, specifically impacting versions prior to 8.3R4 for PCS and 5.4R4 for PPS. The vulnerability stems from inadequate input validation mechanisms that fail to properly bounds-check user-supplied data during HTTP request processing. When maliciously crafted input is received through web requests, the application's buffer handling routines overflow the allocated stack space, resulting in memory corruption that can be exploited by remote attackers.
The technical implementation of this vulnerability involves the web server's handling of HTTP headers or parameters that are processed without sufficient boundary checks. The stack buffer overflow occurs when the application attempts to copy user-provided data into a fixed-size buffer located on the stack memory segment. This flaw falls under CWE-121 Stack-based Buffer Overflow, which is classified as a fundamental memory safety issue where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The vulnerability's exploitation potential is heightened by the fact that it occurs within a network service that is typically accessible from external networks, making it a prime target for remote attacks.
The operational impact of this vulnerability extends beyond simple memory corruption to potentially enable full remote code execution capabilities. When successfully exploited, the buffer overflow can be leveraged to overwrite return addresses, function pointers, or other critical memory locations within the web server process. This allows attackers to redirect execution flow and potentially inject malicious code into the running process. The implications for organizations using affected Pulse Secure appliances are severe, as they may face complete compromise of their network security infrastructure. Attackers could gain unauthorized access to sensitive network resources, potentially leading to data breaches, lateral movement within the network, and complete system takeover. The vulnerability affects organizations that rely on Pulse Secure appliances for remote access and network security policies, making it particularly dangerous in enterprise environments where these devices serve as primary gateways for secure remote connectivity.
Mitigation strategies for CVE-2018-5299 should prioritize immediate patching of affected appliances to versions 8.3R4 for PCS and 5.4R4 for PPS, as provided by Pulse Secure. Organizations should also implement network segmentation to limit access to affected appliances and monitor network traffic for signs of exploitation attempts. Additional defensive measures include configuring web application firewalls to filter suspicious HTTP requests and implementing strict input validation controls. The vulnerability aligns with ATT&CK technique T1203 Exploitation for Client Execution, where attackers leverage remote access capabilities to establish persistent access to target systems. Security teams should also consider conducting thorough vulnerability assessments of their entire network infrastructure to identify any other potentially affected devices running older versions of Pulse Secure software, as the attack surface extends beyond just the directly vulnerable appliances to include any systems that may rely on compromised secure access points.