CVE-2020-3353 in Identity Services Engine
Summary
by MITRE
A vulnerability in the syslog processing engine of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a race condition that may occur when syslog messages are processed. An attacker could exploit this vulnerability by sending a high rate of syslog messages to an affected device. A successful exploit could allow the attacker to cause the Application Server process to crash, resulting in a DoS condition.
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Analysis
by VulDB Data Team • 10/21/2020
The vulnerability identified as CVE-2020-3353 resides within the syslog processing engine of Cisco Identity Services Engine platforms, representing a critical security weakness that exposes network infrastructure to unauthorized disruption. This flaw specifically targets the application server process responsible for handling syslog messages, creating a pathway for malicious actors to compromise system availability through carefully crafted network traffic. The Cisco Identity Services Engine serves as a cornerstone for network access control and identity management, making this vulnerability particularly concerning for enterprise environments that rely on its services for security policy enforcement and user authentication.
The technical root cause of this vulnerability stems from a race condition present in the syslog processing logic of the affected Cisco ISE devices. A race condition occurs when multiple processes or threads attempt to access and modify shared resources concurrently without proper synchronization mechanisms, leading to unpredictable behavior and potential system instability. In this specific case, the race condition manifests when the syslog processing engine handles high-volume message streams, where timing dependencies between message parsing, buffer management, and memory allocation create opportunities for process corruption. The flaw is classified under CWE-362, which specifically addresses Race Conditions, and aligns with ATT&CK technique T1499.004 for Network Denial of Service, demonstrating how this vulnerability can be exploited to disrupt network operations.
The operational impact of exploiting CVE-2020-3353 extends beyond simple service disruption, potentially compromising the entire network security infrastructure managed by the affected Cisco ISE device. When the Application Server process crashes due to the race condition, it results in complete denial of service for network access control services, effectively removing the device's ability to enforce security policies, authenticate users, or monitor network traffic. This disruption can cascade through enterprise networks, as the ISE device typically serves as a central authority for identity verification and access control, meaning that a successful attack could render critical network security functions ineffective. The vulnerability's remote exploitability means that attackers need not have physical access to the device or be within the local network, making it particularly dangerous for organizations with exposed management interfaces.
Organizations affected by CVE-2020-3353 should prioritize immediate implementation of mitigations while planning for official patches from Cisco. The most effective immediate response involves configuring network access controls to restrict syslog message sources to trusted entities only, implementing rate limiting on syslog traffic to prevent flood conditions, and monitoring system logs for signs of exploitation attempts. Network administrators should also consider disabling syslog processing for non-critical services when possible, as this reduces the attack surface for the vulnerable race condition. The vulnerability's classification as a DoS condition means that traditional intrusion detection systems may not immediately flag the attack, as the behavior appears as legitimate system instability rather than malicious network traffic, requiring specialized monitoring approaches to detect exploitation attempts. Organizations should also review their incident response procedures to ensure preparedness for handling potential service disruptions caused by this vulnerability, as the recovery process may require system restarts and potential reconfiguration of network access policies.