Tim Newsham, senior research scientist at Guardent, said that although the vulnerability he found in the Transmission Control Protocol is quite similar to one identified in 1985 by another researcher, it differs in several important ways.
The original problem, discovered by AT&T's Robert Morris, was that ISNs (Initial Sequence Numbers) generated at the beginning of TCP sessions to authenticate subsequent packets were predictable and could be used to create a forged connection between an attacker and a remote host. This, in turn, would enable the attacker to impersonate a trusted host.
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