Yes, there are alternative methods such as FTP, SSH, Gmail, Twitter, and so on. A lot of tools and PoC codes can be found on the internet for exfiltration of data. And, it's not totally undetectable, these techniques help you avoid detection to a certain level, but we should consider the fact that Blue team may also know about these tools and might be monitoring tool-specific channels for any activity.
Frequency analysis is one of the known ciphertext attacks. This is based on the study of the frequency of letters or groups of letters in a ciphertext. Frequency analysis is used for breaking substitution ciphers. The general idea is to find the popular letters in the ciphertext and to try to replace them with ...
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