AlmaLinux OS 9 must disable the Asynchronous Transfer Mode (ATM) kernel module.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-269341	SRG-OS-000095-GPOS-00049	ALMA-09-029610	SV-269341r1050223_rule	2025-02-20	1

Description
The ATM is a transport layer protocol designed for digital transmission of multiple types of traffic, including telephony (voice), data, and video signals, in one network without the use of separate overlay networks. Disabling ATM protects the system against exploitation of any flaws in its implementation.

ℹ️ Check
Verify that AlmaLinux OS 9 disables the ability to load the atm kernel module with the following command: $ grep -r atm /etc/modprobe.conf /etc/modprobe.d/* /etc/modprobe.d/atm.conf:install atm /bin/false /etc/modprobe.d/atm.conf:blacklist atm If the command does not return any output, or the line is commented out, and use of atm is not documented with the information system security officer (ISSO) as an operational requirement, this is a finding.

ℹ️ Check

Verify that AlmaLinux OS 9 disables the ability to load the atm kernel module with the following command: $ grep -r atm /etc/modprobe.conf /etc/modprobe.d/* /etc/modprobe.d/atm.conf:install atm /bin/false /etc/modprobe.d/atm.conf:blacklist atm If the command does not return any output, or the line is commented out, and use of atm is not documented with the information system security officer (ISSO) as an operational requirement, this is a finding.

✔️ Fix
To configure the system to prevent the atm kernel module from being loaded, run the following command: $ cat << EOF \| tee /etc/modprobe.d/atm.conf install atm /bin/false blacklist atm EOF