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Spoofed TCP RST issue on imx6 sabresd with android 4.2.2

Question asked by Steve Yang on Jul 26, 2016

Hi ,

I got a spoofed TCP RST issue on imx6 sabresd with android 4.2.2 and kernel version 3.0.35.


The problem as following, the imx6 sabresd processes spoofed TCP RST packets. This plugin creates a TCP session to an open port on sabresd device. It sends a character to the port, if it get a reply other than RST packets it indicates that the session is alive, and then it spoofs a RST whit the sequence number incremented by 512 from the valid tuple defining the socket(i.e. srchost, dsthost, srcport, dstport). It then sends a character to the socket created to check for a RST from the host. If it gets a RST from sabresd device, then that indicates that the system accepted and processed the spoofed RST. When this scan was launched on Central HMI, from the packet capture is was observed that the spoofed RST packet close the TCP session successfully.

Could anyone tell me how to disable  processing TCP packets with spoofed sequence number ??