CVE-2021-25216 is a high-severity vulnerability affecting ISC BIND versions 9.5.0 through 9.11.29 and 9.12.0 through 9.16.13, as well as certain versions of the BIND Supported Preview Edition and the BIND 9.17 development branch. This vulnerability allows for potential remote code execution and server crashes when the BIND server is configured to utilize GSS-TSIG features. While the default settings of BIND do not expose the vulnerable code path, explicit configuration changes can render the server vulnerable.
The urgency to address this vulnerability is underscored by a CVSS score of 8.1, indicating a high severity level. Risk to organizations includes server crashes and the potential for remote code execution, especially in environments integrating BIND with Samba or Active Directory domain controllers. Organizations utilizing affected configurations must take immediate action to mitigate this risk.
Given the impact of this vulnerability, organizations should prioritize patching immediately. The ISC has outlined plans to remove the vulnerable SPNEGO implementation in upcoming releases, which will further reduce the attack surface for BIND users.
No confirmed public exploits exist for this vulnerability, but given its high profile, it is crucial for security teams to remain vigilant and apply updates as they become available.
Vulnerability Details
The ISC BIND vulnerability detailed in CVE-2021-25216 is particularly concerning due to its potential for exploitation in misconfigured environments. The official description notes that this flaw exists when specific configuration options, such as tkey-gssapi-keytab or tkey-gssapi-credential, are set. In 64-bit platforms, this can lead to a buffer over-read, while 32-bit platforms may experience a buffer overflow, leading to a server crash or remote code execution.
The vulnerability has been assigned a CVSS score of 8.1, categorized as high severity, indicating that it poses significant risks to confidentiality, integrity, and availability. The ISC has recommended that users transition to standard SPNEGO implementations available in the MIT and Heimdal Kerberos libraries, which offer broader support across different operating systems.
The vulnerability is primarily classified under CWE-125, which addresses the issues related to out-of-bounds read.
Technical Analysis
The root cause of CVE-2021-25216 stems from the handling of GSS-TSIG configurations in BIND, where explicit settings can cause the server to enter a vulnerable state. The attack vector is over the network, meaning that an attacker does not need physical access or special privileges to exploit this vulnerability.
The attack complexity is rated as high due to the requirement of specific configuration settings, which are not present in the default installation. No user interaction is needed to exploit this vulnerability, as it can be triggered remotely.
The impacts on confidentiality, integrity, and availability are significant, with high potential for data leaks and server downtime. Security teams should closely monitor their BIND deployments for any unusual behavior.
Risk & Impact Analysis
Organizations utilizing BIND in environments that leverage GSS-TSIG could be significantly impacted by CVE-2021-25216. The blast radius can be extensive, particularly in large networks where BIND is integrated with various services and applications. The urgency for remediation is high, underscored by the CVSS score of 8.1, indicating a serious risk that could lead to unauthorized access and data breaches.
Given that there are no public exploits confirmed, organizations are urged to act swiftly to apply patches and configure their systems securely to prevent potential attacks. Regular audits and updates of configurations should be part of the security posture for any organization using BIND.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions of BIND from 9.5.0 to 9.11.29, 9.12.0 to 9.16.13, and specific versions of the BIND Supported Preview Edition and the BIND 9.17 development branch are affected. Organizations should assume that all versions prior to vendor patch are vulnerable.
Mitigation & Remediation
Organizations should upgrade to the latest versions of BIND where the ISC SPNEGO implementation has been removed to mitigate this vulnerability. Patching should be prioritized, and configurations should be reviewed to avoid the use of tkey-gssapi-keytab or tkey-gssapi-credential settings unless absolutely necessary. For those unable to upgrade immediately, implementing network controls to limit access to vulnerable services may help reduce exposure.
For further guidance, organizations may consider engaging in continuous security testing to validate their configurations and ensure compliance with security best practices.
Detection Guidance
Monitoring logs for unusual access patterns, particularly related to GSS-TSIG configurations, can help detect exploitation attempts. Organizations should also be aware of behavioral anomalies that may indicate an ongoing attack, such as unexpected server crashes or performance degradation.
AppSecure Threat Intelligence Insight
CVE-2021-25216 highlights the importance of regularly reviewing and updating configurations in security-sensitive applications like BIND. The trend towards integrating legacy systems with modern architectures, such as Samba and Active Directory, can increase vulnerability exposure if not managed carefully.
Security teams should remain vigilant about the potential risks posed by misconfigurations and outdated implementations in their environments. Implementing a robust vulnerability management program can help organizations proactively identify and mitigate these risks before they can be exploited.
Additionally, exploring penetration testing methodologies will provide deeper insights into the security posture of their systems and assist in fortifying defenses against emerging threats.
In summary, CVE-2021-25216 is a critical reminder for organizations to maintain vigilance and proactive measures in securing their network services.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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