CVE-2011-1184 in Tomcat
Summary
by MITRE
The HTTP Digest Access Authentication implementation in Apache Tomcat 5.5.x before 5.5.34, 6.x before 6.0.33, and 7.x before 7.0.12 does not have the expected countermeasures against replay attacks, which makes it easier for remote attackers to bypass intended access restrictions by sniffing the network for valid requests, related to lack of checking of nonce (aka server nonce) and nc (aka nonce-count or client nonce count) values.
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Analysis
by VulDB Data Team • 11/28/2021
The vulnerability described in CVE-2011-1184 represents a critical weakness in the HTTP Digest Access Authentication mechanism implemented within Apache Tomcat versions prior to the specified patches. This authentication method was designed to provide a more secure alternative to basic authentication by using cryptographic hashing to protect credentials without transmitting passwords in plaintext. However, the implementation in affected Tomcat versions contained significant design flaws that undermined its security guarantees and created exploitable conditions for network-based attacks.
The core technical flaw lies in the insufficient validation of nonce and nonce-count values within the digest authentication process. In properly implemented digest authentication, the server generates a unique nonce value for each authentication request that should be used only once, while the client maintains a nonce-count that increments with each subsequent request using the same nonce. The vulnerability occurs because the Tomcat implementation fails to properly validate these values, allowing attackers to capture valid authentication requests from the network and replay them against the server. This weakness directly violates the fundamental security principle that authentication tokens should be time-limited and non-reusable, as outlined in the CWE-310 security principle related to cryptographic weaknesses.
The operational impact of this vulnerability is substantial as it enables remote attackers to bypass access controls without requiring knowledge of valid credentials. Attackers can simply monitor network traffic to capture legitimate authentication requests and then replay these captured requests to gain unauthorized access to protected resources. This makes the vulnerability particularly dangerous in environments where network sniffing is possible, such as in shared network segments or when using unencrypted communication channels. The attack vector is straightforward and effective, requiring minimal technical expertise while providing significant access privileges, making it a preferred target for malicious actors seeking to exploit web application security weaknesses.
The vulnerability directly relates to ATT&CK technique T1566.002 which involves credential access through network sniffing and replay attacks. Organizations using affected Tomcat versions face increased risk of unauthorized system access, data breaches, and privilege escalation attacks. The lack of proper nonce validation creates a persistent security gap that remains exploitable until the affected software versions are patched, making it essential for administrators to assess their deployment environments and apply the necessary security updates. This vulnerability demonstrates the critical importance of proper cryptographic implementation and the potential consequences when authentication mechanisms fail to enforce essential security controls such as replay protection.
Mitigation strategies should focus on immediate patching of all affected Tomcat installations to the recommended versions that contain proper nonce validation. Administrators should also consider implementing additional network security controls such as encrypted communication channels using TLS to prevent credential interception. Organizations should conduct comprehensive vulnerability assessments to identify all instances of affected software and ensure that authentication mechanisms are properly configured to enforce strict replay protection. The implementation of additional security layers including intrusion detection systems and network monitoring can help detect and prevent exploitation attempts of this vulnerability.