Check: ACF2-ES-000870
IBM z/OS ACF2 STIG:
ACF2-ES-000870
(in versions v9 r2 through v8 r2)
Title
ACF2 PSWD GSO record value must be set to require the change of at least 50 percent of the total number of characters when passwords are changed. (Cat II impact)
Discussion
If the operating system allows the user to consecutively reuse extensive portions of passwords, this increases the chances of password compromise by increasing the window of opportunity for attempts at guessing and brute-force attacks. The number of changed characters refers to the number of changes required with respect to the total number of positions in the current password. In other words, characters may be the same within the two passwords; however, the positions of the like characters must be different. If the password length is an odd number then number of changed characters must be rounded up. For example, a password length of 15 characters must require the change of at least eight characters.
Check Content
From an ACF command screen enter: SET CONTROL(GSO) LIST PSWD If "PSWDSIM" is set to "4", this is not a finding.
Fix Text
Configure the Password option "PSWDSIM" to "4".
Additional Identifiers
Rule ID: SV-223504r1001111_rule
Vulnerability ID: V-223504
Group Title: SRG-OS-000072-GPOS-00040
Expert Comments
CCIs
| Number | Definition |
|---|---|
| CCI-000195 |
The information system, for password-based authentication, when new passwords are created, enforces that at least an organization-defined number of characters are changed. |
| CCI-004065 |
For password-based authentication, employ automated tools to assist the user in selecting strong password authenticators. |
| CCI-004066 |
For password-based authentication, enforce organization-defined composition and complexity rules. |
Controls
| Number | Title |
|---|---|
| IA-5(1) |
Password-based Authentication |