AD Starter Scan - Null sessions

medium Nessus Plugin ID 150488


The Anonymous or Everyone foreign security principal is part of the 'Pre-Windows 2000 Compatible Access' group.


When Microsoft released the first version of Active Directory, an option was added to enable compatibility with older systems. This was done by adding a Pre-Windows 2000 Compatible Access group, with read permissions on the majority of the domain objects and configuration data. When compatibility with legacy systems is allowed, this group is populated with the Everyone identity, which contains the Anonymous user. This allows unauthenticated users to read all the configuration data in the domain. An attacker can use this feature to discover targets or carry out brute-force attacks.

Note: The AD Starter Scan and associated plugins are intended to be used with smaller AD deployments for purposes of preliminary analysis. Accurate preliminary analysis can be expected for AD deployments with up to 5000 users, groups or machines and incomplete results will be returned for larger AD deployments with Nessus, Security Center and Vulnerability Management. For more information on the issues discovered by the Active Directory Starter Scan plugins, please refer to this blog post -


The following members of the Pre-Windows 2000 compatible access group should be removed:
- ANONYMOUS, with SID S-1-5-7
- EVERYONE, with SID S-1-1-0

See Also

Plugin Details

Severity: Medium

ID: 150488

File Name: adsi_null_session.nbin

Version: 1.84

Type: local

Agent: windows

Family: Windows

Published: 7/29/2021

Updated: 2/22/2024

Supported Sensors: Nessus Agent, Nessus

Risk Information

CVSS Score Rationale: Score based on an in-depth analysis by tenable.


Risk Factor: Medium

Base Score: 6.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N

CVSS Score Source: manual


Risk Factor: Medium

Base Score: 6.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Vulnerability Information

CPE: cpe:/a:microsoft:active_directory

Required KB Items: ldap_enum_group/available