CVE-2017-10981 in FreeRADIUS
Summary
by MITRE
An FR-GV-204 issue in FreeRADIUS 2.x before 2.2.10 allows "DHCP - Memory leak in fr_dhcp_decode()" and a denial of service.
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Analysis
by VulDB Data Team • 12/13/2022
The vulnerability identified as CVE-2017-10981 represents a critical memory management flaw within the FreeRADIUS authentication server software version 2.x prior to 2.2.10. This issue specifically affects the DHCP protocol implementation within the radius server, where a memory leak occurs during the fr_dhcp_decode() function execution. The flaw manifests when processing DHCP packets, creating a condition where allocated memory is not properly released back to the system, leading to progressive memory consumption over time. This type of vulnerability falls under the category of memory leak issues that are commonly classified as CWE-401, which represents "Improper Release of Memory Before Removal from Pool" and aligns with the broader category of resource management flaws in software systems.
The operational impact of this vulnerability extends beyond simple resource consumption as it creates a reliable denial of service condition for the affected FreeRADIUS server. An attacker or malicious actor can exploit this weakness by sending specifically crafted DHCP packets to the vulnerable server, causing the memory leak to occur repeatedly. As the memory consumption increases, the server gradually becomes less responsive and eventually becomes unresponsive, effectively rendering the authentication service unavailable to legitimate users. This makes the vulnerability particularly dangerous in network environments where FreeRADIUS servers are critical for authentication and network access control, as it can be leveraged to disrupt network services and potentially cause broader operational outages. The attack pattern aligns with the MITRE ATT&CK technique T1499.004, which describes "Network Denial of Service" and can be classified as a service disruption attack vector.
The technical exploitation of this vulnerability requires minimal complexity and can be executed through standard network packet crafting techniques. The fr_dhcp_decode() function processes DHCP options and data structures without proper memory cleanup mechanisms, causing memory allocated for DHCP packet handling to remain in use indefinitely. This memory leak accumulates over time and can be triggered repeatedly, making the attack scalable and persistent. The vulnerability affects the core authentication infrastructure, as FreeRADIUS servers often serve as central points for network access control and user authentication. Organizations utilizing FreeRADIUS for network access control, wireless authentication, or VPN access are particularly at risk, as the memory leak can cause complete service interruption. The issue demonstrates poor memory management practices and highlights the importance of proper resource deallocation in server-side applications handling network protocols. The vulnerability also relates to CWE-121, which addresses "Stack-based Buffer Overflow" and "Heap-based Buffer Overflow" conditions, though in this case it manifests as a memory leak rather than a buffer overflow. Mitigation efforts should focus on upgrading to FreeRADIUS version 2.2.10 or later, implementing network monitoring to detect abnormal memory consumption patterns, and applying rate limiting to DHCP packet processing to prevent rapid exploitation.