CVE-2016-8625 in macOS
Summary
by MITRE
curl before version 7.51.0 uses outdated IDNA 2003 standard to handle International Domain Names and this may lead users to potentially and unknowingly issue network transfer requests to the wrong host.
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Analysis
by VulDB Data Team • 10/07/2022
The vulnerability identified as CVE-2016-8625 represents a critical security flaw in the curl command-line tool and library that affects versions prior to 7.51.0. This issue stems from curl's reliance on the outdated IDNA 2003 standard for handling International Domain Names, which creates a significant risk of user deception and potential security breaches. The problem specifically manifests when users attempt to access internationalized domain names that contain characters from non-ascii character sets, as the outdated processing mechanism fails to properly validate and normalize these domain names according to current security standards.
The technical flaw in curl's implementation involves the improper handling of Internationalized Domain Names in Applications, where the software continues to utilize the deprecated IDNA 2003 specification instead of upgrading to the more secure IDNA 2008 standard. This outdated approach allows for potential homograph attacks where malicious actors can register domain names that visually appear identical to legitimate domains but contain characters from different character sets that are indistinguishable to the human eye. The vulnerability creates a scenario where users might unknowingly navigate to malicious hosts while believing they are connecting to legitimate services, as the domain name resolution process does not properly account for the security implications of character set variations.
The operational impact of this vulnerability extends beyond simple user confusion to encompass serious security risks including man-in-the-middle attacks, phishing attempts, and unauthorized data access. When users enter what they believe to be a legitimate domain name, the outdated IDNA processing might resolve it to a different host than intended, potentially redirecting traffic to malicious servers. This risk is particularly pronounced in environments where users frequently access internationalized domains or when organizations operate in multi-lingual contexts where domain names might contain characters from various scripts. The vulnerability effectively undermines the trust model that users place in domain name resolution, creating an attack surface that can be exploited by threat actors to conduct sophisticated deception campaigns.
Organizations and security practitioners should immediately upgrade to curl version 7.51.0 or later to remediate this vulnerability, as the fix incorporates proper IDNA 2008 compliance and enhanced domain name validation mechanisms. The mitigation strategy should also include implementing additional network monitoring to detect unusual traffic patterns that might indicate attempted exploitation of this vulnerability, as well as conducting security awareness training for users to recognize potential deception attempts. This vulnerability aligns with CWE-1004 which addresses insecure default settings in security-critical components, and represents a clear violation of the principle of least privilege in domain name resolution. From an ATT&CK perspective, this vulnerability maps to techniques involving social engineering and credential access through deceptive network communications, as attackers can leverage the confusion created by the improper domain name handling to gain unauthorized access to systems and data. The remediation process should also involve reviewing and updating network security policies to ensure proper validation of domain names and implementing additional checks for internationalized domain name processing within network infrastructure.