A flaw was found in the c-ares library, where a missing input validation check of host names returned by DNS (Domain Name Servers) can lead to output of wrong hostnames which might potentially lead to Domain Hijacking. The highest threat from this vulnerability is to confidentiality and integrity as well as system availability.
The vulnerability has a CVSS score of 5.6, classifying it as medium severity. Organizations should prioritize patching immediately as the potential impact includes unauthorized access and manipulation of sensitive data.
Currently, there are no known exploits in the wild for CVE-2021-3672, but the absence of public proof of concept (PoC) does not mitigate the risk. Organizations should remain vigilant and address this vulnerability to protect against future attacks.
With the threat landscape continually evolving, it is critical for organizations to implement effective remediation strategies to safeguard their systems.
Vulnerability Details
CVE-2021-3672 affects the c-ares library, a widely used asynchronous DNS resolver. The vulnerability arises due to a lack of input validation checks on hostnames returned by DNS servers. This flaw could allow attackers to manipulate DNS responses, potentially leading to domain hijacking.
The vulnerability has been assigned a CVSS 3.1 score of 5.6, indicating a medium severity level. The attack vector is classified as network-based, with a high attack complexity, meaning that exploitation would require specific conditions to be met.
Affected systems include various versions of the c-ares library, Fedora versions 33 and 34, and multiple Red Hat Enterprise Linux distributions, among others.
Technical Analysis
The root cause of this vulnerability is the absence of proper input validation for hostnames returned by DNS queries. Attackers may leverage this flaw to redirect traffic from legitimate domains to malicious sites, compromising confidentiality and integrity.
The attack vector is network-based, requiring no user interaction or privileges. However, the complexity is high, as attackers would need to manipulate DNS settings or responses to successfully exploit this vulnerability.
The impacts on confidentiality, integrity, and availability are classified as low, but the potential for domain hijacking poses serious risks to organizations.
Risk & Impact Analysis
Risk to organizations includes potential unauthorized access to sensitive information and control over domain resources. With the medium severity score, organizations should assess the impact of this vulnerability on their operations and implement necessary patches.
The blast radius could be significant, especially for organizations relying heavily on DNS for their operations. Given the possibility of domain hijacking, organizations must take proactive measures.
Due to the lack of known exploitation in the wild, organizations should still treat this vulnerability seriously and prioritize remediation in their patch management cycles.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
This vulnerability affects c-ares versions prior to 1.17.2, Fedora 33 and 34, and multiple versions of Red Hat Enterprise Linux, including 7.0, 7.7, 8.0, and others. Organizations should ensure they are using updated and patched versions to mitigate this risk.
Mitigation & Remediation
Organizations should prioritize patching by upgrading to the latest version of the c-ares library, specifically version 1.17.2 or newer. In addition, apply updates for affected Fedora and Red Hat distributions as soon as they are available.
If immediate patching is not possible, organizations can implement network controls to restrict access to vulnerable services and enhance monitoring for abnormal DNS behavior.
For further guidance, organizations may refer to the penetration testing services to identify weaknesses related to this vulnerability.
Detection Guidance
To detect potential exploitation of CVE-2021-3672, organizations should monitor DNS query logs for unusual patterns or anomalies. Additionally, logging and analyzing application behavior can help identify unauthorized hostname resolutions.
Behavioral anomalies in application responses or network traffic may indicate attempts to exploit this vulnerability. Implementing network intrusion detection systems can provide alerts on suspicious activities.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-3672 lies in the necessity for robust input validation mechanisms in libraries handling DNS queries. This vulnerability represents a trend where inadequate validation can lead to severe security risks.
Organizations should take this incident as a lesson to bolster their security measures, ensuring that all components in their technology stack are scrutinized for potential vulnerabilities.
For strategic defensive takeaways, organizations are encouraged to conduct regular vulnerability management to identify and remediate similar weaknesses proactively.
Staying informed about emerging threats and maintaining an active security posture will help organizations mitigate risks associated with vulnerabilities like CVE-2021-3672.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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