## Login Error
The main idea finding the flag is decryption of AES CBC encryption.

#### Step-1:
I am not that good at AES encryption, so looked up [here](https://dunsp4rce.github.io/csictf-2020/crypto/2020/07/21/Login-Error.html).

#### Step-2:
Finally the flag becomes:
`csictf{Sh4u!d_hav3_n0t_u5ed_CBC}`