CVE-2017-8342 in Radicale
Summary
by MITRE
Radicale before 1.1.2 and 2.x before 2.0.0rc2 is prone to timing oracles and simple brute-force attacks when using the htpasswd authentication method.
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Analysis
by VulDB Data Team • 08/23/2024
The vulnerability identified as CVE-2017-8342 affects Radicale, an open-source calendar and contact server that implements the CalDAV and CardDAV protocols. This issue specifically impacts versions prior to 1.1.2 and 2.x versions before 2.0.0rc2, creating a significant security weakness in the authentication mechanism that can be exploited by malicious actors. The vulnerability stems from the implementation of htpasswd authentication, which is a standard method for HTTP basic authentication that stores user credentials in a password file.
The technical flaw lies in the timing characteristics of the authentication process when using htpasswd. When a user attempts to authenticate, the server performs a comparison between the provided password and the stored hash, but this comparison process exhibits timing variations that can be measured and analyzed by attackers. This timing oracle allows adversaries to determine the correct password through systematic brute-force attacks, as the time taken to process each password guess varies depending on how many characters match the correct password. The vulnerability is classified as a timing attack, which is a form of side-channel attack that exploits the time taken to execute cryptographic algorithms or authentication routines.
The operational impact of this vulnerability is substantial as it fundamentally undermines the security of user accounts protected by htpasswd authentication. Attackers can systematically test password guesses and use the timing differences to deduce valid credentials without requiring extensive computational resources or sophisticated attack infrastructure. This makes the vulnerability particularly dangerous because it can be exploited by attackers with minimal technical expertise and can be performed at scale. The vulnerability affects the confidentiality and integrity of user data, as successful exploitation can lead to unauthorized access to calendar and contact information, potentially exposing sensitive personal or business data. Organizations using Radicale with htpasswd authentication are particularly at risk since this authentication method is commonly deployed in environments where user privacy is critical.
The vulnerability aligns with CWE-347, which addresses improper certificate validation and authentication, and relates to ATT&CK technique T1110.003 for Brute Force attacks. The timing oracle creates a predictable pattern that attackers can exploit to reduce the search space for password discovery, making brute-force attacks significantly more efficient than they would be with properly implemented authentication mechanisms. Organizations should immediately upgrade to Radicale versions 1.1.2 or 2.0.0rc2, which contain fixes for this timing vulnerability. Alternative authentication methods such as OAuth or certificate-based authentication should be considered for enhanced security. Additionally, implementing rate limiting and account lockout mechanisms can provide additional defense-in-depth measures against brute-force attacks. The fix typically involves ensuring that password comparison operations take constant time regardless of input values, eliminating the timing variations that enable the oracle attack.