A paper, expected to be presented at USENIX, describes new attacks against RC4 that make plaintext recovery times practical and within reach of hackers. Researchers from the University of Leuven explain how an attacker can use these findings to decrypt a user s website cookie, for example, that should be secured over an encrypted channel. Their attacks, however, are not limited to cookies, but they say they can also gain access to personal information. Microsoft and other leading technology companies have already taken steps to deprecate RC4 in.
Source: https://threatpost.com/new-rc4-attack-dramatically-reduces-plaintext-recovery-time/113808/