CVE-2011-5124 in ProxySG
Summary
by MITRE
Stack-based buffer overflow in the BCAAA component before build 60258, as used by Blue Coat ProxySG 4.2.3 through 6.1 and ProxyOne, allows remote attackers to execute arbitrary code via a large packet to the synchronization port (16102/tcp).
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Analysis
by VulDB Data Team • 05/24/2025
The vulnerability identified as CVE-2011-5124 represents a critical stack-based buffer overflow flaw within the BCAAA component of Blue Coat ProxySG appliances and ProxyOne systems. This vulnerability affects versions ranging from 4.2.3 through 6.1 and persists in builds prior to 60258. The flaw manifests when the system receives a specially crafted packet on the synchronization port designated as 16102/tcp, creating a condition where attacker-controlled data exceeds the bounds of a fixed-size stack buffer. The technical implementation involves improper input validation mechanisms that fail to adequately check packet sizes before processing, leading to memory corruption that can be exploited to overwrite adjacent stack memory locations including return addresses and control data.
From an operational perspective, this vulnerability presents a severe threat to network security infrastructure as it enables remote code execution without requiring authentication or prior access to the system. The attack surface is particularly concerning given that the affected port 16102/tcp is commonly exposed in network environments where these appliances operate, making exploitation feasible from external network positions. The buffer overflow allows attackers to potentially overwrite the instruction pointer and execute arbitrary code with the privileges of the affected service process, which typically runs with elevated system permissions. This represents a direct violation of the principle of least privilege and creates a persistent backdoor for attackers to maintain access and escalate privileges within the network environment.
The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflow conditions where data is written beyond the boundaries of a stack-allocated buffer. From an attack framework perspective, this vulnerability maps to multiple ATT&CK techniques including T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation. The exploitability is enhanced by the fact that no authentication is required to trigger the vulnerability, making it particularly dangerous in environments where the appliance is directly exposed to untrusted networks. Network segmentation and firewall rules that restrict access to port 16102/tcp can provide temporary mitigation, but the fundamental flaw requires patching or upgrading to affected systems.
Organizations should prioritize immediate remediation through official Blue Coat patches or firmware updates that address the buffer overflow in the BCAAA component. System administrators should implement network segmentation to isolate affected appliances from untrusted networks and consider disabling the synchronization port if not actively required for legitimate business operations. Monitoring for suspicious traffic patterns on port 16102/tcp and implementing intrusion detection systems can help identify potential exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation and memory management in network security appliances, where a single flaw can compromise entire network infrastructures. Regular vulnerability assessments and security audits should be conducted to identify similar issues in other network components and ensure comprehensive protection against similar buffer overflow vulnerabilities.