Title

The system must implement non-executable program stacks. (Cat II impact)

Discussion

A common type of exploit is the stack buffer overflow. An application receives, from an attacker, more data than it is prepared for and stores this information on its stack, writing beyond the space reserved for it. This can be designed to cause execution of the data written on the stack. One mechanism to mitigate this vulnerability is for the system to not allow the execution of instructions in sections of memory identified as part of the stack.

Check Content

On 64-bit systems, verify the sed_config (Stack Execution Disable) setting is "all". # lsattr -El sys0 -a sed_config If the second field is not "all", this is a finding. (32-bit systems do not support sed_config. This is a permanent finding on 32-bit AIX systems.)

Fix Text

Change the sed_config setting to disable stack execution for all processes. # chdev -l sys0 -a sed_config=all To assess the impact of updating sed_config, the "all+monitor" setting may be used temporarily. This temporary update does not mitigate the finding. Reboot the system for the new setting to take effect.

Additional Identifiers

Rule ID: SV-39504r1_rule

Vulnerability ID: V-11999

Group Title: GEN003540

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.