Information
The recommendation is to activate TE to enhance system integrity by specifying authorized locations for applications to hamper attacks from unauthorized locations using
Trojan horse
style tactics.
TE provides a robust system integrity checking process.
Hackers utilize any opening they can find to infiltrate a system. One common attack pattern includes getting an unauthorized program (aka Trojan horse) installed anywhere on the target system. One of the integrity checks TE provides is an
authorized
aka
allowed
aka Trusted Executition Path ( TEP ).
Enforcing a TEP is a low invasive mechanism of TEP and provides a high level continuous system integrity.This ensures that programs are only executed from well-defined (
allowed
) locations. Best practice installation and maintaince (e.g., system updates) are needed to ensure only trusted programs are installed in these locations and not malicious code masquerading as a true program.
Solution
NOTE : Your configuration of TE is dependent on the unique requirements of your environment.
To configure TE to enforce a
Trusted Execution Path
( TEP ) you need to know the intended secure path.e.g., SecurePath="/usr/bin:/usr/sbin"
Perform the following:
# First disable both TE and TEP
trustchk -p TE=OFF TEP=OFF
# Set the secure TEP variable
trustchk -p TEP=${SecurePath}
# Enable TE and TEP
trustchk -p TE=ON TEP=ON
Further details regarding planning and implementation of TE can be found within the IBM AIX 7 Infocentre:
https://www.ibm.com/docs/en/aix/7.3?topic=configuration-trusted-execution
Impact:
Testing is recommended. An additional directory may be needed, e.g., for trusted applications not installed in the BOS default locations.
Additional QA testing should verify that only directories actually needed are included in the TEP - otherwise an unnecessary, perhaps un-watched, directory leaves a potential for an attack.