The vulnerability exists in the password storage of Mobateks MobaXterm in versions below 25.0. MobaXTerm uses an initialisation vector (IV) consisting only of zero bytes and a master key to encrypt each password individually. In the default configuration, on opening MobaXTerm, the user is prompted for their password. A derivative of the password is used as the master key. As both the master key and the IV are the same for each stored password, the AES CFB ciphertext depends only on the plaintext (the password). The static IV and master key make it easier to obtain sensitive information and to decrypt data when it is stored at rest.
The product uses a cryptographic primitive that uses an Initialization Vector (IV), but the product does not generate IVs that are sufficiently unpredictable or unique according to the expected cryptographic requirements for that primitive.
Different cipher modes have different requirements for their IVs. When choosing and implementing a mode, it is important to understand those requirements in order to keep security guarantees intact. Generally, it is safest to generate a random IV, since it will be both unpredictable and have a very low chance of being non-unique. IVs do not have to be kept secret, so if generating duplicate IVs is a concern, a list of already-used IVs can be kept and checked against.
NIST offers recommendations on generation of IVs for modes of which they have approved. These include options for when random IVs are not practical. For CBC, CFB, and OFB, see [REF-1175]; for GCM, see [REF-1178].