CVE-2013-4685 in Junos
Summary
by MITRE
Buffer overflow in flowd in Juniper Junos 10.4 before 10.4S14, 11.4 before 11.4R7, 12.1 before 12.1R6, and 12.1X44 before 12.1X44-D15 on SRX devices, when Captive Portal is enabled with the UAC enforcer role, allows remote attackers to execute arbitrary code via crafted HTTP requests, aka PR 849100.
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Analysis
by VulDB Data Team • 12/25/2024
The vulnerability identified as CVE-2013-4685 represents a critical buffer overflow flaw within the flowd daemon of Juniper Junos operating systems. This issue specifically affects SRX series devices and manifests when the Captive Portal feature is enabled alongside the UAC enforcer role configuration. The vulnerability stems from inadequate input validation within the flowd process that handles HTTP request processing, creating a condition where maliciously crafted HTTP requests can trigger memory corruption. The flaw exists in multiple Junos versions including 10.4 prior to 10.4S14, 11.4 prior to 11.4R7, 12.1 prior to 12.1R6, and 12.1X44 prior to 12.1X44-D15, indicating a widespread impact across several major release branches.
The technical implementation of this vulnerability involves the flowd daemon's insufficient bounds checking when processing HTTP headers and request parameters. When the UAC enforcer role is active within the Captive Portal framework, the daemon receives and processes HTTP traffic that flows through the authentication system. Attackers can exploit this by crafting HTTP requests containing oversized or malformed data that exceeds the allocated buffer space, causing a stack-based buffer overflow. This memory corruption can be leveraged to overwrite critical program execution pointers, enabling remote code execution with the privileges of the flowd process. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which is classified as a high-risk weakness in the Common Weakness Enumeration catalog. The attack surface is particularly concerning as it allows unauthenticated remote code execution, making it a prime target for network-level exploits.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with persistent access to SRX device infrastructure. Once exploited, the remote code execution capability enables attackers to manipulate network traffic flow, potentially creating backdoors, exfiltrating sensitive data, or disrupting network services. The vulnerability affects network security appliances that rely on captive portal functionality for user authentication, making it particularly dangerous in enterprise environments where these devices control critical network access points. The UAC enforcer role specifically targets authentication enforcement, meaning that exploitation could compromise the entire authentication infrastructure of the network. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 Command and Scripting Interpreter: Python and T1566.001 Phishing: Spearphishing Attachment, as attackers could use the compromised device to launch further network attacks or establish persistent access. The vulnerability also relates to T1078 Valid Accounts and T1082 System Information Discovery, as the compromised device could be used to gather network intelligence or escalate privileges further within the network infrastructure.
Mitigation strategies for CVE-2013-4685 require immediate implementation of vendor-supplied security patches and firmware updates. Juniper released specific fixes for affected versions, and administrators should prioritize upgrading to patched releases. Network segmentation and access control measures should be implemented to limit exposure, particularly by disabling Captive Portal functionality when not required or restricting access to the affected device to trusted networks only. Monitoring for anomalous HTTP traffic patterns and unusual authentication behavior can help detect exploitation attempts. The vulnerability demonstrates the importance of secure coding practices and input validation, particularly in network services handling external HTTP traffic. Organizations should implement comprehensive vulnerability management processes that include regular security assessments, penetration testing, and continuous monitoring for similar buffer overflow conditions. Additionally, network administrators should consider implementing intrusion detection systems that can identify and alert on suspicious HTTP request patterns that may indicate exploitation attempts against known buffer overflow vulnerabilities. The incident underscores the critical need for maintaining current security patches and the importance of validating network device configurations to prevent exploitation of authentication system vulnerabilities.