CVE-2021-0276 in SBR Carrier
Summary
by MITRE • 07/16/2021
A stack-based Buffer Overflow vulnerability in Juniper Networks SBR Carrier with EAP (Extensible Authentication Protocol) authentication configured, allows an attacker sending specific packets causing the radius daemon to crash resulting with a Denial of Service (DoS) or leading to remote code execution (RCE). By continuously sending this specific packets, an attacker can repeatedly crash the radius daemon, causing a sustained Denial of Service (DoS). This issue affects Juniper Networks SBR Carrier: 8.4.1 versions prior to 8.4.1R19; 8.5.0 versions prior to 8.5.0R10; 8.6.0 versions prior to 8.6.0R4.
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Analysis
by VulDB Data Team • 07/19/2021
This vulnerability represents a critical stack-based buffer overflow flaw within Juniper Networks SBR Carrier systems that utilize EAP authentication mechanisms. The issue resides in the radius daemon component responsible for handling authentication requests, creating a significant security risk that can be exploited through carefully crafted network packets. The vulnerability specifically affects versions of the SBR Carrier software where the daemon fails to properly validate input data when processing EAP authentication requests, leading to memory corruption that can be leveraged for system compromise.
The technical exploitation of this vulnerability occurs through the manipulation of EAP authentication packets sent to the radius daemon, where insufficient bounds checking allows an attacker to overflow the stack buffer and potentially overwrite critical memory locations. This type of vulnerability maps directly to CWE-121 Stack-based Buffer Overflow, which is classified as a high-severity weakness in the Common Weakness Enumeration catalog. The flaw enables an attacker to either trigger immediate denial of service through daemon crashes or potentially achieve remote code execution, depending on the precise memory corruption achieved during the overflow event. According to ATT&CK framework, this represents a privilege escalation and defense evasion technique through service interruption.
The operational impact of this vulnerability extends beyond simple service disruption, as it provides attackers with the capability to maintain persistent system compromise through repeated exploitation attempts. The sustained denial of service attack can effectively render the authentication service unavailable to legitimate users while potentially allowing for more sophisticated attacks. Organizations running affected versions of Juniper SBR Carrier are particularly vulnerable since the daemon crash can occur with minimal network interaction, making detection and mitigation challenging. The vulnerability affects multiple software versions including 8.4.1 prior to 8.4.1R19, 8.5.0 prior to 8.5.0R10, and 8.6.0 prior to 8.6.0R4, indicating a widespread issue across the product line.
Mitigation strategies should focus on immediate patch deployment to the affected software versions, as Juniper has released security updates addressing this specific vulnerability. Network segmentation and access control measures can provide additional defense-in-depth layers, while monitoring for unusual authentication traffic patterns may help detect exploitation attempts. The implementation of network intrusion detection systems capable of identifying malformed EAP packets can serve as an early warning mechanism. Organizations should also consider disabling EAP authentication where possible and implementing additional authentication mechanisms to reduce attack surface. Regular security assessments and vulnerability scanning should be conducted to identify any other potentially affected systems within the network infrastructure.