The vulnerability identified as CVE-2024-9681 affects haxx's curl component, classified with a medium severity (CVSS score of 6.5). This vulnerability allows the expiry time for a subdomain's HTTP Strict Transport Security (HSTS) cache entry to overwrite that of its parent domain. This can lead to unintended consequences for applications using curl with HSTS enabled.
This vulnerability can occur when curl uses URLs with the insecure HTTP scheme and interacts with hosts like x.example.com (subdomain) and example.com (parent domain). The issue arises when the HSTS cache has been populated, which can happen through prior HTTPS accesses or manual population.
When a subdomain responds with Strict-Transport-Security headers, the expiry timeout can bleed over into the parent domain's cache. As a result, HTTP accesses to the parent domain may be converted to HTTPS for a duration that is different from what was intended by the origin server. This can lead to access failures if the parent domain stops supporting HTTPS before the incorrectly set timeout expires.
Given the potential access issues this vulnerability introduces, organizations utilizing curl with HSTS should prioritize patching to mitigate risks associated with unintended HTTP to HTTPS transitions.
Vulnerability Details
CVE-2024-9681 is described in detail as a bug affecting haxx's curl when HSTS is enabled. It has a CVSS score of 6.5, indicating medium severity. This vulnerability impacts curl versions between 7.74.0 and 8.11.0 (exclusive). The vulnerability has been classified under CWE-697, highlighting issues related to improper handling of HTTP response headers.
Technical Analysis
The root cause of the vulnerability lies in the way curl handles HSTS cache entries for subdomains and their parent domains. When a subdomain sets an HSTS header, it can unintentionally alter the expiry time for the parent domain's cache entry. The attack vector is classified as NETWORK, with a high attack complexity, meaning that an attacker would need to manipulate HSTS headers effectively.
The vulnerability requires no privileges and does not necessitate user interaction, allowing attackers to exploit it remotely. The impacts on confidentiality are negligible, but integrity could be significantly compromised due to the incorrect handling of security protocols, resulting in potential availability issues when accessing the parent domain.
Risk & Impact Analysis
The real-world risk posed by CVE-2024-9681 is moderate, with the potential for significant consequences in environments that depend on secure communications through curl. Should the parent domain's cache entry expire incorrectly, it could lead to unauthorized access or denial of service when transitioning between HTTP and HTTPS.
Organizations should assess their use of curl, particularly in applications that leverage HSTS, and consider the potential blast radius of this vulnerability. As this vulnerability is classified with a medium severity, organizations should address it in their priority patch cycle.
Given the current exploitability and the absence of known exploits, organizations should still remain vigilant and prepare for potential future developments related to this vulnerability.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability affects curl versions from 7.74.0 up to, but not including, 8.11.0. Organizations using these versions should prioritize applying the latest patches.
Mitigation & Remediation
Organizations should immediately patch curl to the latest version to mitigate this vulnerability. For those unable to upgrade, consider implementing network controls to restrict access to affected components and monitor usage of curl in environments where HSTS is enabled.
For comprehensive security, organizations may benefit from conducting a thorough security assessment. They can refer to the application security assessment to identify and remediate potential vulnerabilities.
Detection Guidance
Monitoring logs for unusual HTTP/HTTPS transitions can help identify potential exploitation attempts of this vulnerability. Additionally, organizations should be vigilant for behavioral anomalies related to curl operations, especially in applications that heavily depend on secure communications.
AppSecure Threat Intelligence Insight
CVE-2024-9681 highlights the need for organizations to adopt robust security practices when managing HSTS configurations. As vulnerabilities evolve, security teams must stay informed about potential risks associated with legacy systems and configurations.
To enhance security posture, organizations should consider implementing regular security audits and assessments. Engaging in penetration testing methodologies can also provide insights into potential vulnerabilities and help prioritize remediation efforts.
As organizations proceed with their security enhancements, they should ensure continuous monitoring and adaptation to emerging threats. Learning from vulnerabilities like CVE-2024-9681 will aid in developing a resilient security framework.
For further insights into defensive strategies, organizations can explore the vulnerability management program design to strengthen their overall security posture.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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