CVE-2022-24704 in ACCEL-PPP
Summary
by MITRE • 02/15/2022
The rad_packet_recv function in opt/src/accel-pppd/radius/packet.c suffers from a buffer overflow vulnerability, whereby user input len is copied into a fixed buffer &attr->val.integer without any bound checks. If the client connects to the server and sends a large radius packet, a buffer overflow vulnerability will be triggered.
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Analysis
by VulDB Data Team • 02/18/2022
The vulnerability identified as CVE-2022-24704 represents a critical buffer overflow flaw within the rad_packet_recv function of the accel-pppd radius packet processing module. This issue exists in the file opt/src/accel-pppd/radius/packet.c where the system fails to implement proper bounds checking when handling user-provided input data. The vulnerability specifically manifests when the len parameter from incoming radius packets is directly copied into a fixed-size buffer located at &attr->val.integer without any validation of the data length against the buffer capacity. This fundamental flaw in input validation creates an exploitable condition that can be leveraged by remote attackers to manipulate memory contents and potentially execute arbitrary code.
The technical implementation of this vulnerability stems from a classic buffer overflow pattern where the system assumes that incoming data will not exceed predetermined limits without performing explicit validation. When a malicious client establishes a connection and sends a radius packet containing an oversized len value, the system's failure to check buffer boundaries results in data being written beyond the allocated memory space for attr->val.integer. This condition violates fundamental security principles and creates opportunities for memory corruption that can be exploited through various attack vectors. The vulnerability aligns with CWE-121 which describes unsafe use of a fixed-length buffer and represents a direct violation of secure coding practices.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to potentially enable remote code execution and privilege escalation within the affected system. An attacker who successfully exploits this buffer overflow can overwrite adjacent memory locations, potentially corrupting program execution flow, manipulating critical data structures, or injecting malicious code into the running process. The affected accel-pppd service operates at a privileged level typically handling authentication and authorization functions, making successful exploitation particularly dangerous as it could lead to complete system compromise. The vulnerability affects systems implementing RADIUS authentication services where the accel-pppd module is utilized for network access control.
Mitigation strategies for CVE-2022-24704 should prioritize immediate patching of the affected software components to address the root cause through proper bounds checking implementation. Organizations should implement input validation measures that enforce strict limits on radius packet attributes before copying data into fixed buffers. Network segmentation and access control measures can help limit the attack surface by restricting direct access to RADIUS services from untrusted networks. Monitoring and logging should be enhanced to detect anomalous packet sizes or patterns that might indicate exploitation attempts. The fix should incorporate defensive programming practices such as using safe string handling functions and implementing proper error handling for buffer overflow conditions. This vulnerability demonstrates the importance of adhering to the principle of least privilege and maintaining robust input validation as outlined in the MITRE ATT&CK framework's defense evasion techniques. System administrators should also consider implementing intrusion detection systems that can identify and alert on suspicious RADIUS traffic patterns that may indicate exploitation attempts.