More Flexible Assessments of Windows ACLs

Tenable recently increased the flexibility of performing configuration assessments of Windows  access control lists (ACLs) with the Nessus compliance checks.

Previously, an ACL policy could only be built with exact understanding if it were "inherited" or "not inherited". For large numbers of checks, it might not make any difference if an ACL were inherited from someplace else or not, just that the actual ACL was correct.

For example, to perform a file ACL test without regard if it is "inherited" or "not inherited", use the phrase "not used" with the "acl_inheritance" keyword. Below is an example .audit file which performs a file ACL test without regard if the policy were inherited or not:

<file_acl: "ASU1">

<user: "Administrators">
  acl_inheritance: "not used"
  acl_apply: "This folder, subfolders and files"
  acl_allow: "Full Control"
</user>
<user: "System">
  acl_inheritance: "not used"
  acl_apply: "This folder, subfolders and files"
  acl_allow: "Full Control"
</user>

<user: "Users">
  acl_inheritance: "not used"
  acl_apply: "this folder only"
  acl_allow: "list folder / read data" | "read attributes" | 
             "read extended attributes" | "create files / write data" |  
             "create folders / append data" | "write attributes" |  
             "write extended attributes" | "read permissions" 
</user>
</acl>

These changes effect the acl_inheritance  keyword for auditing ACLs of files, registry entries and services.   

Obtaining These Checks

Tenable customers who manage their Nessus scanners with a Direct Feed subscription or the Security Center have already received this update. If your organization is not connected to the Internet or performing regular updates, the change was made available on December 29th.