T-SQL : Weak hashing algorithm

The hash function used is not secure. Its use may result in loss of data privacy.

Sensitive Data Exposure vulnerabilities rank third in the OWASP Top 10 2017 web application vulnerability rating.

Hash functions MD2, MD5, SHA1 have known vulnerabilities. Finding collisions for MD2 and MD5 functions does not require significant resources; a similar problem was solved for SHA1. If these functions are used to store valuable information (such as passwords), its confidentiality may be compromised.

The hash function used to store passwords, in addition to collision resistance, should not be too fast. This complicates the attack by exhaustive search. For this purpose, specialized hash functions have been developed: PBKDF2, bcrypt, scrypt.

Have user passwords stored on the server encrypted using an insecure hash function (such as MD5). Possible attack scenario:

1. An attacker gains access to the encrypted password database.
2. An attacker, using a hashing algorithm vulnerability, calculates a string for which the hashing algorithm gives the same value as for the user’s password.
3. The attacker authenticates using the computed string.