4.5.17 Ensure tcp_tcpsecure is configured

Information

The tcp_tcpsecure parameter value determines if the system is protected from three specific TCP vulnerabilities: The values are OR ed together. If all three values are to be set the value to set is: 1|2|4 (or 7).

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Fake SYN - This is used to terminate an established connection. A tcp_tcpsecure bit-value of 1 protects the system from this vulnerability.

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Fake RST - As above, this is used to terminate an established connection. A tcp_tcpsecure bit-value of 2 protects the system from this vulnerability.

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Fake data - A hacker may inject fake data into an established connection. A tcp_tcpsecure bit-value of 4 protects the system from this vulnerability.

The tcp_tcpsecure parameter should be set to 7 This means that the system will be protected from TCP connection reset and data integrity attacks.

Solution

In /etc/tunables/nextboot add the tcp_tcpsecure entry:

no -p -o tcp_tcpsecure=7

This makes the change permanent by adding the entry into /etc/tunables/nextboot

See Also

https://workbench.cisecurity.org/benchmarks/10385

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6, 800-53|CM-7, CSCv7|9.2

Plugin: Unix

Control ID: b5e5db0bb5a14d7875f5f08d65943e0a9034f14b1989a7020789fcc1f24b7df4