CVE-2015-3310 in PPP Package
Summary
by MITRE
Buffer overflow in the rc_mksid function in plugins/radius/util.c in Paul's PPP Package (ppp) 2.4.6 and earlier, when the PID for pppd is greater than 65535, allows remote attackers to cause a denial of service (crash) via a start accounting message to the RADIUS server.
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Analysis
by VulDB Data Team • 11/25/2024
The vulnerability identified as CVE-2015-3310 represents a critical buffer overflow flaw within Paul's PPP Package version 2.4.6 and earlier implementations. This issue specifically manifests in the rc_mksid function located within the plugins/radius/util.c file of the ppp package. The flaw occurs under specific conditions where the process identifier for pppd exceeds the 65535 threshold, creating a scenario where remote attackers can exploit this weakness to trigger system instability. The vulnerability is particularly concerning because it enables adversaries to execute a denial of service attack that results in system crashes, effectively rendering the affected service unavailable to legitimate users. The buffer overflow condition arises from inadequate input validation and improper handling of process identifiers that exceed the expected range, creating a scenario where memory corruption can occur during RADIUS accounting message processing.
The technical exploitation of this vulnerability requires remote attackers to send a specially crafted start accounting message to the RADIUS server that is configured to use the affected ppp package. When the pppd process identifier surpasses the 65535 limit, the rc_mksid function fails to properly manage the buffer allocation, leading to memory overflow conditions that cause the application to crash. This type of vulnerability falls under CWE-121, which categorizes buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The operational impact of this vulnerability extends beyond simple service disruption, as it can potentially be leveraged as a stepping stone for more sophisticated attacks, particularly when the affected system serves as a critical network infrastructure component. The flaw demonstrates poor input validation practices and inadequate error handling mechanisms within the RADIUS accounting implementation, which are fundamental security requirements outlined in various cybersecurity frameworks and standards.
The implications of this vulnerability align with ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion or system instability. Attackers can exploit this weakness to systematically disrupt network connectivity services that rely on PPP authentication and accounting mechanisms. The affected systems typically include network access servers, routers, and network infrastructure devices that utilize RADIUS for authentication and accounting purposes. Organizations implementing the vulnerable ppp package in their network infrastructure face significant operational risks, as this vulnerability can be exploited without requiring authentication credentials, making it particularly dangerous in environments where network access control is critical. The vulnerability's impact is amplified when considering that RADIUS servers often serve as central points of authentication for network access, making successful exploitation potentially disruptive to large-scale network operations and user access management systems.
Mitigation strategies for CVE-2015-3310 should prioritize immediate patching of affected systems to upgrade to ppp package versions 2.4.7 or later, where the buffer overflow has been resolved through proper input validation and bounds checking. System administrators should also implement network monitoring to detect unusual RADIUS accounting message patterns that might indicate exploitation attempts, while configuring access controls to limit RADIUS server exposure to trusted networks only. Additional defensive measures include implementing intrusion detection systems that can identify malformed RADIUS accounting messages and configuring automatic system monitoring to detect service disruptions. Organizations should also conduct comprehensive vulnerability assessments to identify all systems running affected versions of the ppp package and ensure proper network segmentation to limit the potential impact of successful exploitation attempts. The remediation process should include thorough testing of patched systems to verify that the vulnerability has been fully addressed without introducing regressions in network connectivity or authentication services.