w2k auditing / intrusion detection secure labs overview what is auditing / effective auditing...

W2K Auditing / Intrusion Detection

Secure Labs

Overview

What is Auditing / Effective Auditing Auditing Strategy / Intrusion Detection Strategy W2K Auditing Functionality / Event Logs Audit Policy / Group Policy Types of Auditing Utilities and Tools What to look for ? Questions ?

Windows 2000 Security Features

Active Directory Kerberose Encrypting File System (EFS) Public Key Certificate Manager Internet Protocol Security (IPSec) Enhanced VPN (L2TP) Enhanced Access Control Enhanced Auditing Subsystem

What is Auditing

Auditing tracks the activity of users and processes by recording selected types of events in the logs of a server or workstation.

Will provide information required to spot attempted attacks, to investigate what happened when an incident occurred, and to possibly provide evidence in support of an investigation

Without Auditing

Finding security problems can be difficult if not impossible

You cannot fix it – if you don’t know about it ! System will remain open or vulnerable to attack

What is an Event ?

Any significant occurrence in a system that requires notification– Example

Service did not start Driver did not load Information from an application Logon Failure

What is Intrusion Detection (ID) ?

The ability to detect inappropriate, incorrect, or anomalous activity

www.sans.org/newlook/resources/IDFAQ/ID_FAQ.htm

Host vs. Network Based ID

Host based ID involves loading software(s) on the system to be monitored– Uses log files or auditing agents for information

Network based ID monitors actual network traffic (packets)– Uses packets as the source of information

Effective Auditing

Infrastructure Security Policy

Execution

Lan / Wan (Entry Points)

Security Entities (External)

Security Entities (Internal)

Auditing Strategy

Why are you auditing ? Do you need different policy for different systems ? Who is responsible for log collection and analysis ? Who should have access to the audit logs ? Is the loss of some audit information acceptable ?

Auditing Strategy (cont.)

Who reviews the logs ? How long should you keep them ? What is the escalation procedure should an intrusion be

detected ? Does the discovery of certain events require immediate

actions ? Do audit logs need to be collected and analyzed centrally ? Will the logs be used for legal action ?

Effective Auditing

Auditing– Vulnerability Management

Checking current configuration against a defined baseline

– Threat Management Real-time detection of a threat or actual intrusion

– Collection and Analysis Management Ability to reveal information related to use and abuse

Effective Auditing (cont.)

Too Much Auditing– Performance Impact– Could hide significant events– The first rule in Auditing is “Restraint”

Too Little Auditing– Not effective

W2K Audit Logs

Application System Security Directory Service File Replication DNS Server

Audit Log Categories

Error– Loss of functionality or data, service failure

Warning– Recoverable events; not immediately urgent

Information– Successful operation (Application, Service or Driver)

Success Audit Failure Audit

W2K Audit Log Properties

Group Policy is recommended method to set audit log properties

Only the Application, System and Security log settings can be set via Group Policy

Settings include;– Overwrite events as needed– Overwrite events older than x days– Do not overwrite events (clear manually)

W2K Audit Log Properties (cont.)

Halting the system when the Security Log is full– If the Security Log reaches maximum size, by default the

system will stop auditing– CrashOnAuditFail

Can be used to stop the system (Blue Screen) if auditing cannot continue

Could result in a Denial of Service An Administrator must sign on to the system, backup and clear

the audit log then reset the registry value Use this option only in the most extreme situation

Microsoft Recommendations (Log Size)

Log Domain Control

File / Print

Data- Base

Web Server

Ras Server

Wrkstn

Security 5-10 mb 2-4 mb 2-4 mb 2-4 mb 5-10 mb 1 mb

System 1-2 mb 1-2 mb 1-2 mb 1-2 mb 1-2 mb 1 mb

Apps 1-2 mb 1-2 mb 1-2 mb 1-2 mb 1-2 mb 1 mb

Event Viewer

View audit information for all logs Manage audit logs (View, Export and Archive) Apply filters to current view Configure audit log properties Open saved audit logs (.EVT)

Event Log Security

Access to the event logs is controlled to prevent unauthorized modification or viewing

Four Type of Accounts are used for the logs;– LocalSystem– Administrator– ServerOperator– Everyone

Event Log Security (cont.)

LOG Application Access

Application LocalSystem R, W, C

Administrator R, W, C

ServerOp R, W, C

Everyone R, W



Security LocalSystem R, W, C

Administrator R, C

Everyone



System LocalSystem R, W, C

Administrator R, W, C

ServerOp R, C

Everyone R

Only the LocalSystem account can write to the Security Log

On domain controllers these permissions extend to the three additional logs

Administrators can only manage the Security Log if they have the proper privileges

Registry keys can further prevent Guest accounts from access (RestrictGuestAccess = 1)


Configuring Audit Policy

Two Stage Process– Set high-level audit policy

Which events to audit ?

– Set auditing on specific objects What objects ?

No audit policy is turned on by default

Configuring Audit Policy (cont.)

Event Categories– Audit Account Logon Events

This will record the success or failure of a user to authenticate to the local computer across the network

– Audit Account Management This audits the creation, modification or deletion of user accounts

or groups


Event Categories (cont.)– Audit Directory Service Access

Administrators can monitor access to Active Directory Only available on Domain Controllers

– Audit Logon Events Records the success or failure of a user to interactively log on to

the local computer

– Audit Object Access Records the successful or failed attempts to access a specific

object such as directory, file and printer objects


Event Categories (cont.)– Audit Policy Change

Records any successful or failed attempts to make high level changes to security policy – including privilege assignments and audit policy changes

– Audit Privilege Use Records all successful and failed attempts to use a privilege


Event Categories (cont.)– Audit Process Tracking

Provide detailed tracking information for events such as process activation handle dups, indirect object access and exits from processes

– Audit System Events Records events that affect the security of the whole system

Audit Privileges

To be able to implement and configure audit policy settings, you must have the following privileges;– Generate Security Audits

Allows a process to make entries to the Security Log

– Managing Auditing and Security Log Allows a user to specify object access auditing options

Group Policy

Allows central management of W2K computers Domain Group Policy will override Local Policy Group Policy Objects (GPO)

– A collection of configuration settings Computer Configuration

– Settings applied at boot time User Configuration

– Settings applied at logon time

W2K reapplies Group Policy at specified intervals

Group Policy (cont.)

Hierarchy– Apply configuration of local computers GPO– Apply configuration of computers site-linked GPO– Apply configuration of domain-linked GPO– Apply configuration of computers OU-linked GPO

GPO settings can conflict, last applied wins Setting can be set to “Not Configured”

Configuring Object Auditing

Each object has a Security Descriptor associated with it that details the Groups or users that can access the object, and the types of access granted to those groups and users (DACL)-discretionary access control list

Each Security descriptor also contains auditing information (SACL)-system access control list

Auditing File and Folder Objects

Must be a NTFS file system Must specify the files or folders to audit Must specify the action that will trigger the audit

event Must be logged on as a member of the

Administrators group to enable auditing

Type of Folder Access

Displaying names of files in the folder Displaying the folders attributes Changing the folders attributes Creating subdirectories and files Going to the folders subdirectories Displaying the folders owners and permissions Deleting the folder Changing the folders permissions Changing the folders ownership

Type of File Access

Displaying the files data Displaying the files attributes Displaying the files owner and Permissions Changing the file Changing the files attributes Running the file Deleting the file Changing the file permissions Changing the files ownership

Setup Auditing on a File or Folder

Open Windows Explorer Locate the File or Folder Right Click, Select Properties, Select Security Tab Select Advanced, Select Audit Tab Select Add Type the name of the User, Select OK Under Access, Select Successful, Failure or Both To prevent other Folders/Files from inheriting these audit entries,

Select “Apply These Auditing Entries to Objects and/or Containers Within This Container Only”

Auditing Printers

Options for Print Object Auditing– Print– Manage Printers– Manage Documents– Read Permissions– Change Permissions– Take Ownership

Auditing the Registry

Options for Registry Auditing– Query Value– Set Value– Create Subkey– Enumerate Subkeys– Notify– Create Link– Delete– Write DACL– Write Owner– Read Control

Auditing DHCP

Windows 2000 Server has enhanced DHCP Auditing– Can specify the dir path of the DHCP log files– Can specify a maximum size restriction in mb for all audit logs

managed by the DHCP service– Can specify an interval for writes to the audit log before checking

available disk space– Can specify minimum disk requirements to continue DHCP auditing– Can disable / enable audit logging at each DHCP server

Auditing Message Queues

Audit messages for a single Message Queue object get logged on the computer that performs the operation. Therefore, audit messages for Message Queue objects may be scattered around the network

Audit messages are only created when a queue is accessed, not each time a message is received or sent

Auditing IPSEC Security

Can be filtered using “Oakley” in the Security log

Microsoft Audit Recommendations

See Excel Spreadsheet

Windows 2000 Resource Kit

Error and Event Messages (Help File) Logevent.exe

– Utility to add entries to the Event Log Cyber Safe Log Analyst

– Event Log analysis tool w/ reporting W2000events.mdb

– Access DB of all events for the System, Security and Applications logs

AuditPol.exe– Command line utility to change audit policy

Windows 2000 Resource Kit (cont.)

Elogdmp.exe– Event log query tool

Dumpel.exe– Event log dump utility w/ filter capabilities; Dumps to tab separated text file

Uptime.exe– Event log utility to determine Availability, Reliability and current Uptime– Can also monitor Service Pack and OS Failures

Security Config & Analysis Tool

The Security Configuration Tool Set allows you to configure security, and then perform periodic analysis of the system to ensure that the configuration remains intact or to make necessary changes over time

Managing Logs - Export Log

Use Event View MMC to export the current view on the log to a text file

Will use current filter settings

Managing Logs - Archive Log

If you archive a log in log-file format, you can reopen it in Event Viewer. Logs saved as event log files (*.evt) retain the binary data for each event recorded

When you archive a log file, the entire log is saved, regardless of filtering options

The sort order is not retained when logs are saved.

Managing - Archive Log (cont.)

If you archive a log in text or comma-delimited format (*.txt and *.csv, respectively), you can reopen the log in other programs such as word processing or spreadsheet programs. Logs saved in text or comma-delimited format do not retain the binary data

Archiving has no effect on the current contents of the active log

Log Monitoring Tools

Dorian Software, Event Analyst, http://www.doriansoft.com TNT Software, Event Log Monitor, http://www.tntsoftware.com Aelita Software, EventAdmin, http://www.aelita.com RippleTech, Logcaster, http://www.rippletech.com Opalis Robot, http://www.opalis.com Argent Software, Guardian, http://www.argentsoftware.com BindView, http://www.bindview.com BMC Patrol, http://www.bmc.com/patrol NetCool, http://www.micromuse.com/products NetIQ, http://www.netiq.com/products RoboMon, http://www.heroix.com/product_info.htm

Event Log - Targeted

Event Log cleared at random– A manual log should be kept for each server– When an event log is cleared, it should correspond to an

entry in the manual event log

Event Log flooding– Used to overwhelm the administrator– Used as a Denial of Service– Sophisticated hackers could write to the security log

Monitoring the Security Logs

Must monitor users that have Admin rights Monitor System Events and Policy Change

categories to watch for tampering– Restarts (Security Event ID 512)– Shutdowns (System Event ID 6006 Clean, 6008 Dirty)– Audit Policy Changes (Security Event ID 612)– Time Change (Security Event ID 577)

Monitoring the Security Logs (cont.)

Policy should exist to manage the audit logs– Look for manual clear of the audit log (Security Event ID 517)– Proper policy should make this event rare

Logon and Logoff (Successful)– Logon uses Event ID 528

Local Console Interactive = Type 2 Drive Map or Network Connect = Type 3 Batch Logon = Type 4 Service Logon = Type 5 Unlocks Wrstn = Type 7

– Logoff uses Event ID 538

Monitoring the Security Logs (cont.)

Logon and Logoff (Un-successful)– Have Event Ids that represent the reason for the failure– Most common failure

“Unknown user name or bad password” Event ID 529 Disabled Account = Event ID 531 Account Lockout = Event ID 539 Logon Outside of time allowed = Event ID 530

– Event ID 534 is logged in the case of insufficient rights to perform an action; such as log on at the console or gain access to a computer

– Event ID 537 is a general failure “An unexpected error occurred during logon”

Watch for Intrusions by monitoring Event Ids 529 – 537 and 539

Example Using SQL Server

If All Else Fails….

“And if you wrong us, shall we not revenge ?”

William Shakespeare