AIX must use Loadable Password Algorithm (LPA) password hashing algorithm.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-91315	AIX7-00-001128	SV-101413r1_rule		High

Description
The default legacy password hashing algorithm, crypt(), uses only the first 8 characters from the password string, meaning the user's password is truncated to eight characters. If the password is shorter than 8 characters, it is padded with zero bits on the right. The crypt() is a modified DES algorithm that is vulnerable to brute force password guessing attacks and also to cracking the DES-hashing algorithm by using techniques such as pre-computation. With the Loadable Password Algorithm (LPA) framework release, AIX implemented a set of LPAs using MD5, SHA2, and Blowfish algorithms. These IBM proprietary password algorithms support a password longer than 8 characters and Unicode characters in passwords.

Description

The default legacy password hashing algorithm, crypt(), uses only the first 8 characters from the password string, meaning the user's password is truncated to eight characters. If the password is shorter than 8 characters, it is padded with zero bits on the right. The crypt() is a modified DES algorithm that is vulnerable to brute force password guessing attacks and also to cracking the DES-hashing algorithm by using techniques such as pre-computation. With the Loadable Password Algorithm (LPA) framework release, AIX implemented a set of LPAs using MD5, SHA2, and Blowfish algorithms. These IBM proprietary password algorithms support a password longer than 8 characters and Unicode characters in passwords.

STIG	Date
IBM AIX 7.x Security Technical Implementation Guide	2019-04-29

Details

Check Text ( C-90469r4_chk )
From the command prompt, run the following command to check system wide password algorithm: # lssec -f /etc/security/login.cfg -s usw -a pwd_algorithm usw pwd_algorithm=ssha512 If the "pwd_algorithm" is not set to "ssha512", or "ssha256", this is a finding.

Fix Text (F-97513r1_fix)
From the command prompt, run the following command to set system wide password algorithm to "ssha512" so that it supports passwords longer than 8-character: # chsec -f /etc/security/login.cfg -s usw -a pwd_algorithm=ssha512 For each users who have hashed passwords in "/etc/security/passwd" file that does not start with "{ssha512}", run passwd commands to reset the users' passwords so that they have to change their passwords in the next login: # passwd [user_name]

Fix Text (F-97513r1_fix)

From the command prompt, run the following command to set system wide password algorithm to "ssha512" so that it supports passwords longer than 8-character:
# chsec -f /etc/security/login.cfg -s usw -a pwd_algorithm=ssha512

For each users who have hashed passwords in "/etc/security/passwd" file that does not start with "{ssha512}", run passwd commands to reset the users' passwords so that they have to change their passwords in the next login:
# passwd [user_name]