Cryptography / Weak Transport Layer Security

Web and API


Weak Transport Layer Security (TLS) is a type of cryptography vulnerability in which the secure communication between a web application or API and a client is weak or incomplete. This vulnerability is categorized as CWE-311 in the Common Weakness Enumeration (CWE) directory and is described as "Inadequate Encryption Strength" in the OWASP Testing Guide. Weak TLS can be caused by a variety of misconfigurations and insecure settings, such as an outdated TLS protocol version, a weak cipher suite, or weak key exchange algorithms.


Weak TLS can put an organization's networks, systems, and data at risk of attack. Attackers can exploit weak TLS to intercept and decrypt confidential data, allowing them to gain access to sensitive information or inject malicious code into the application to compromise security. For example, an attacker could use a man-in-the-middle attack to intercept and modify data in transit.

The risk of weak TLS depends on the strength of the encryption used. Weak encryption can make it easier for attackers to crack the encryption and gain access to sensitive information.


The best way to protect against weak TLS is to ensure that the TLS protocol and cipher suites used by an application are configured securely and up to date. Organizations should regularly audit their TLS settings to identify any weak or outdated configurations. If possible, organizations should use the latest version of TLS and only allow strong cipher suites. Additionally, organizations should use strong key exchange algorithms and secure authentication methods.


The following example shows a weak TLS configuration using TLSv1.2 with a weak cipher suite (TLS_ECDHE_RSA_WITH_RC4_128_SHA):


To correct this configuration, the cipher suite should be updated to a more secure one (e.g. TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384), and the TLS protocol version should be updated to the latest version (e.g. TLSv1.3).

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