CVE-2021-1625 describes a vulnerability in the Zone-Based Policy Firewall feature of Cisco IOS XE Software. This medium-severity vulnerability, with a CVSS score of 5.8, could allow an unauthenticated, remote attacker to prevent the Zone-Based Policy Firewall from correctly classifying traffic. The flaw arises from the lack of inspection of ICMP and UDP responder-to-initiator flows when Unified Threat Defense (UTD) or Application Quality of Experience (AppQoE) is configured. An attacker could exploit this vulnerability by sending UDP or ICMP flows through the network.
A successful exploit could enable attackers to inject traffic through the Zone-Based Policy Firewall, potentially leading to traffic being dropped due to incorrect classification or generating inaccurate reporting figures via high-speed logging (HSL). The urgency for organizations to address this issue cannot be overstated.
Organizations must prioritize patching this vulnerability to prevent unauthorized traffic manipulation and ensure accurate traffic reporting within their network infrastructure.
The vulnerability was published on September 23, 2021, and has been classified as modified. It is essential for security teams to remain vigilant and implement necessary updates as part of their security protocols.
Organizations should assess their systems for the affected version of Cisco IOS XE and take corrective actions immediately.
Vulnerability Details
A vulnerability in the Zone-Based Policy Firewall feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to prevent the Zone-Based Policy Firewall from correctly classifying traffic. This vulnerability exists because ICMP and UDP responder-to-initiator flows are not inspected when the Zone-Based Policy Firewall has either Unified Threat Defense (UTD) or Application Quality of Experience (AppQoE) configured. An attacker could exploit this vulnerability by attempting to send UDP or ICMP flows through the network. A successful exploit could allow the attacker to inject traffic through the Zone-Based Policy Firewall, resulting in traffic being dropped because it is incorrectly classified or in incorrect reporting figures being produced by high-speed logging (HSL).
The CVSS score for this vulnerability is 5.8, indicating a medium severity level. The attack vector is network-based with low complexity and requires no privileges or user interaction. The confidentiality impact is none, the integrity impact is low, and availability impact is none.
Technical Analysis
The root cause of this vulnerability lies in the lack of inspection of certain traffic flows within the Zone-Based Policy Firewall. Specifically, when UTD or AppQoE is configured, ICMP and UDP responder-to-initiator flows are not processed, allowing attackers to exploit this oversight.
The attack vector for this vulnerability is network-based, with the complexity classified as low. Attackers do not require any privileges to exploit this vulnerability, and user interaction is not necessary. The impact on confidentiality is none, while the integrity impact is low due to the potential for incorrect traffic classification.
Organizations should be aware that the availability impact is classified as none, indicating that the vulnerability does not directly disrupt service availability.
Risk & Impact Analysis
Risk to organizations includes the potential for unauthorized traffic manipulation, which could lead to significant disruptions in network management and monitoring. The incorrect classification of traffic can result in dropped packets, leading to poor performance and inefficiencies in network operations.
The blast radius of this vulnerability could be substantial, affecting any organization utilizing Cisco IOS XE with the Zone-Based Policy Firewall configured. It is crucial for organizations to address this vulnerability promptly to mitigate risks associated with traffic management and reporting.
Given the CVSS score of 5.8, organizations should prioritize patching this vulnerability in their security patch cycle. This will help ensure that their systems remain secure and that unauthorized traffic does not compromise their network integrity.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability affects Cisco IOS XE versions up to, but not including, version 17.3.2. Organizations should ensure that any systems running IOS XE are updated to at least this version to mitigate the risk of exploitation.
Mitigation & Remediation
To mitigate this vulnerability, organizations should apply the latest patches provided by Cisco. Upgrading to version 17.3.2 or later is essential to address the vulnerability effectively.
In cases where patching is not immediately feasible, organizations can implement workarounds, such as reconfiguring the Zone-Based Policy Firewall to limit the exposure of vulnerable traffic flows. Additionally, configuration hardening practices should be reviewed and enhanced to further protect network infrastructure.
Organizations should also consider implementing network controls to monitor and restrict suspicious traffic patterns that could exploit this vulnerability. Continuous security testing can help identify potential weaknesses in network configurations.
Detection Guidance
To detect potential exploitation attempts related to this vulnerability, organizations should monitor logs for indicators of unusual ICMP and UDP traffic patterns. Behavioral anomalies that deviate from normal network activity should be investigated.
Network signatures should be updated to identify malicious traffic attempting to exploit this vulnerability. System changes, such as unauthorized configuration alterations in the Zone-Based Policy Firewall, should also be closely monitored.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-1625 lies in the potential for attackers to exploit weaknesses in the traffic classification mechanisms of Cisco's Zone-Based Policy Firewall. This vulnerability highlights a broader trend of misconfigurations leading to security vulnerabilities in network devices.
Security teams should take this opportunity to evaluate their network configurations and ensure that similar vulnerabilities do not exist in their systems. Implementing robust security measures and continuous monitoring can enhance the overall security posture against similar vulnerabilities.
For additional insights on how to strengthen your organization's security framework, organizations can benefit from engaging in services such as penetration testing to identify and address potential vulnerabilities proactively.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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