TCP Hole-in-one

Internet security experts warned of a serious security vulnerability in the Transmission Control Protocol (TCP), a critical communications protocol used on the majority of computer networks in the world, according to an advisory from  National Infrastructure Security Co-ordination Centre (NISCC).

The hole exists in all implementations of TCP that comply with the Internet Engineering Task Force's TCP specification. By exploiting the holes, malicious hackers could cause TCP sessions to end prematurely, creating a denial-of-service attack. The TCP vulnerability could also disrupt communications between routers on the Internet by interrupting BGP (Border Gateway Protocol) sessions that use TCP, the NISCC said.

Sustained exploitation of the hole could lead to a DOS attack affecting "portions of the Internet community."

Research discovered that the current TCP standard allows a malicious hacker to easily guess a unique 32-bit number needed to reset an established TCP connection, because the standard allows sequence numbers in a range of values to be accepted rather than exact matches, according to the NISCC advisory.

Networking experts have known about the potential for such attacks for almost 20 years. However, as Internet use and the use of broadband Internet connections has grown over the years, ISPs and others have gradually increased the size of the window, or range of acceptable sequence numbers that they permit to reset a connection, making a successful DOS attack more plausible.

Now we know the problem.  So what is the fix?

 

Updated On: 11.12.17