CVE-2020-3228 in IOS
Summary
by MITRE
A vulnerability in Security Group Tag Exchange Protocol (SXP) in Cisco IOS Software, Cisco IOS XE Software, and Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability exists because crafted SXP packets are mishandled. An attacker could exploit this vulnerability by sending specifically crafted SXP packets to the affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.
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Analysis
by VulDB Data Team • 10/21/2020
The vulnerability identified as CVE-2020-3228 represents a critical denial of service weakness within the Security Group Tag Exchange Protocol implementation across multiple Cisco networking platforms including IOS, IOS XE, and NX-OS software versions. This flaw resides in the protocol handling mechanism where the system fails to properly validate incoming SXP packets, creating an avenue for malicious actors to disrupt network operations. The Security Group Tag Exchange Protocol serves as a critical component in network security management, facilitating the exchange of security group information between network devices and security appliances. When properly functioning, SXP enables dynamic security policy enforcement and group membership updates across network segments, making it an essential element in enterprise security infrastructure.
The technical exploitation of this vulnerability occurs through the deliberate crafting of malformed SXP packets that trigger improper memory handling within the affected software implementations. These specially crafted packets exploit a buffer overflow condition or improper input validation routine within the SXP processing module, causing the system to enter an unstable state. The flaw manifests when the device attempts to parse and process these malformed packets without adequate bounds checking or error handling mechanisms, leading to memory corruption that ultimately results in system instability. This type of vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios that can occur during improper memory management. The exploitation process requires minimal privileges as the vulnerability is accessible to unauthenticated remote attackers, eliminating the need for prior access credentials or network positioning.
The operational impact of CVE-2020-3228 extends beyond simple service interruption to potentially compromise entire network segments that rely on SXP for security policy enforcement. When an affected device undergoes a reload due to this vulnerability, it disrupts the security group tagging functionality, potentially causing security policy enforcement gaps that could allow unauthorized access to network resources. Network administrators face the challenge of maintaining service availability while addressing the root cause, as the DoS condition can be triggered repeatedly by attackers seeking to maintain persistent disruption. The vulnerability affects critical infrastructure components where SXP is enabled, particularly in enterprise environments where security group management is crucial for network segmentation and access control policies. The attack vector allows for remote exploitation from any location on the network, making it particularly dangerous as it can be leveraged by attackers from outside the organization's perimeter.
Mitigation strategies for this vulnerability require immediate implementation of network access controls and software updates from Cisco to address the underlying protocol handling flaws. Organizations should consider implementing access control lists to filter SXP traffic at network boundaries, particularly disabling SXP functionality on devices where it is not essential for operations. The recommended approach includes applying Cisco's official security patches and updates that address the specific buffer handling issues within the SXP protocol implementation. Network segmentation strategies should be implemented to limit the potential impact of successful exploitation attempts, ensuring that even if one device is compromised, the broader network infrastructure remains protected. Additionally, monitoring systems should be configured to detect unusual traffic patterns associated with SXP packet processing, providing early warning capabilities for potential exploitation attempts. This vulnerability demonstrates the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies to protect critical network infrastructure components from remote exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1499.004 for network denial of service, highlighting the strategic importance of protecting critical network protocols from remote exploitation.