Cryptography / Weak Cipher Suites

Web and API


Weak Cipher Suites, classified as CWE-327 and CWE-310, is a cryptography vulnerability that occurs in web and API systems. It is a type of weakness where a system does not correctly implement cryptographic protocols and algorithms, which can lead to the encryption key being weakened and the system's data being exposed. The CWE directory states that "Weak Cipher Suites can allow attackers to bypass authentication, access sensitive information, and gain privileged access to a system". The OWASP Testing Guide provides further information regarding testing, detection, and exploitation of this vulnerability.


Weak Cipher Suites can be extremely dangerous, as exploitation can lead to a complete breach of system security. It is important for testers to thoroughly check for this vulnerability in order to protect their system from exploitation. A risk assessment should be conducted to determine the likelihood of exploitation and the impact it could have on a system.


The best way to prevent Weak Cipher Suites from occurring is to ensure that all cryptographic protocols and algorithms are correctly implemented. This should be done by using a secure cryptographic library and verifying that the cryptographic keys generated are strong enough to protect the system's data. Additionally, any cryptographic protocols and algorithms that are no longer supported should be removed or disabled.


The following example is a code block taken from CVE-2020-0961, a vulnerability that occurs due to Weak Cipher Suites.

def execute(self, user, passwd):
    self.user = user
    self.passwd = passwd

    # Use weak cipher suite
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.connect(("", 4433))
    s.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 8192)
    s.setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF, 8192)

    ssl_sock = ssl.wrap_socket(s,
        keyfile=None, certfile=None, server_side=False,

This code block shows an example of a vulnerable system that is using an insecure SSL version, SSLv2. This weak cipher suite can allow attackers to bypass authentication and gain access to sensitive data.

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