BTA

BTA is an open-source Active Directory security audit framework. Its goal is to help auditors harvest the information they need to answer such questions as:

• Who has rights over a given object (computer, user account, etc.)?
• Who can read a given mailbox?
• Which are the accounts with domain admin rights?
• Who have extended rights (userForceChangePassword, SendAs, etc.)?
• What are the changes done on an AD between two points in time?

The framework is made of

• an importer able to translate a ntds.dit file, containing all the AD data, into a database
• tools to query the database
  • AD miner framework
  • AD diff utility
  • small utilities (list of databases, etc.)

The comprehensive set of attributes are imported and can be querried including all schema extensions (Exchange, Sharepoint, etc.).

Each question can be crystallized by an AD expert as a miner so that it can be used during all audits without doing the hard work again.

Active Directory Security Analysis

Goal:

• Clean an AD or an AD forest, looking for
  • bad practices
  • forgotten entries
  • backdoors
  • recompromissions
• BTA is an operationnal tool, ought to be
  • deterministic, reliable
  • running a well-established procedure

Install

pip install bta

Use

Audit steps:

1. Extract the ntds.dit file
2. Import the ntds.dit file in a database
3. Look for control points in the database

Extraction

Here is a way to backup NTDS.dit file for a domain controller which is running on Windows 2008. See [2] for more information or for Windows 2003 method.

ntdsutil

activate instance ntds

ifm

create full c:{\bs}NTDS_saved

quit

quit

Importing

• ntds.dit is unusable as-is.
• one ntds.dit is imported into one MongoDB database
• ability to import several ntds.dit in parallel

Examples:

btaimport -C ::mydb /path/to/ntds.dit

btaimport /path/to/*.dit  --multi             \

  --C-from-filename                         \

     "::%s" "basename rmext 'DB' swap plus"

Analysing

• Querying the database
  • analyzing control points of a database: btaminer
  • analyzing differences between 2 bases: btadiff

Analysing control points

• miners crystallize expertise
  • list of admin accounts
  • list of accounts with extended rights
  • list of accounts with password errors
  • list of various timelines

btaminer -t ReST -C ::AD1 Schema --timelineCS created



Analysis by miner [Schema]

==========================



+---------------+-----------------------+

| Date          | Affected class schema |

+===============+=======================+

| 2009-02-11 18 | 234                   |

| 2011-12-20 00 | 267                   |

| 2011-12-22 14 | 3                     |

| 2011-12-23 18 | 46                    |

+---------------+-----------------------+

Analysing differences

• diff
  • diff (naive for the moment) between 2 imports at different points in time
  • noise filtering

    $ btadiff --CA ::ADclean --CB ::ADbackdoor --ignore-defaults
    
    ===============
    
    Starting diffing sd_table
    
    ---------------
    
    AB,101: [] *sd_refcount['14'=>'15']
    
    AB,108: [] *sd_refcount['39'=>'41']
    
    A ,229: []
    
    A ,372: []
    
    AB,423: [] *sd_refcount['3'=>'2']
    
     B,424: []
    
     B,425: []
    
     B,428: []
    
    ---------------
    
    Table [sd_table]: 160 records checked, 2 disappeared, 3 appeared, 3 changed
    
    ===============
    
    [...]

     

    ===============
    
    Starting diffing datatable
    
    ---------------
    
    AB,3586: [DC001] *logonCount['116'=>'117'], *lastLogon['130052518207794051L'=>'130052535716737649L']
    
    AB,3639: [RID Set] *rIDNextRID['1153'=>'1154']
    
    AB,8784: [A:[gc]/B:[gc  DEL:346bf199-8567-4375-ac15-79ec4b42b270]] +isDeleted,
    
             *name["u'gc'"=>"u'gc\\nDEL:346bf199-8"], *dc["u'gc'"=>"u'gc\\nDEL:346bf199-8"]
    
    AB,8785: [A:[DomainDnsZones]/B:[DomainDnsZones  DEL:58b2962b-708c-4c93-99ff-0b7e163131f9]]
    
             +isDeleted, *name["u'DomainDnsZones'"=>"u'DomainDnsZones\\nDE"],
    
             *dc["u'DomainDnsZones'"=>"u'DomainDnsZones\\nDE"]
    
    AB,8786: [A:[ForestDnsZones]/B:[ForestDnsZones  DEL:87f7d8a2-4d05-48d0-8283-9ab084584470]]
    
             +isDeleted, *name["u'ForestDnsZones'"=>"u'ForestDnsZones\\nDE"],
    
             *dc["u'ForestDnsZones'"=>"u'ForestDnsZones\\nDE"]
    
     B,8789: [snorky insomnihack]
    
     B,8790: [gc]
    
     B,8791: [DomainDnsZones]
    
     B,8792: [ForestDnsZones]
    
    ---------------
    
    Table [datatable]: 7636 records checked, 0 disappeared, 4 appeared, 5 changed
    
    ===============

     

Other features

• can give reports in different formats:
  • live dump
  • ReST document
  • zipped tree of CSV files
• audit log of writings in a database
• table consistency checks before mining

Authors

• Airbus Group CERT
• Airbus Group Innovations
• Airbus DS CyberSecurity

Source: https://github.com/airbus-seclab/bta