3.3.16 tcp_tcpsecure

Information

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

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

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.

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.

Rationale:

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.

Default Value:

tcp_tcpsecure = 0

See Also

https://workbench.cisecurity.org/files/4119

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7(12)

Plugin: Unix

Control ID: e1dd665792452b7f1607ef79653c9b9f7d2b86fa73290154473de6349f396030