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Hardening Windows 2003 Web Servers

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Agenda

Physical Security OS Installation Account Policies Local Policies Services User Accounts IP Policies Permissions Hardening IIS Additional Hardening

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General

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GeneralWho should take this course

System Consultants Security Consultants System Architects Anyone who is responsible for the configuration and/or the

administration of a Windows 2003 environment

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GeneralStrategy: Creating a secure environment

Secure current and/or new implementations of the Windows 2003 operating system

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GeneralStrategy: Maintaining a secure environment

Maintain a secure environment by staying on top of security issues that are relevant to your installation

This is a proactive process!!

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GeneralScope of this course

This course will focus on the secure configuration of a Windows 2003 server hosting Internet Information Services (IIS) version 6.0

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GeneralPrerequisites

Experience with IT security Experience with MMC Experience deploying web applications in enterprise

environments Some web application development knowledge will be useful

but is not mandatory

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GeneralWhat happens if I don’t harden my web server?

Most systems can be compromised within 72 hours Corporate humilliation Won’t know if your system is has been/is being attacked Money wasted on reparation and down time Company data/ secrets could be stolen

Some web sites are fed with data that comes from the same database as other internal systems

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Hardening one step at a time

Physical Security --------------------------------------- OS Installation ----------------------------------------- Account Policies ---------------------------------------- Local Policies ------------------------------------------- Services ------------------------------------------------ User Accounts ----------------------------------------- IP Policies------------- --------------------------------- Permissions -------------------------------------------- Hardening IIS ------------------------------------------ Additional Hardening ----------------------------------

Numberof

Weaknesses

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PrerequisitesWhat should

Install ALL necessary software/ services before you begin. Make sure that they ALL work. Why?

If software/ service dosn’t work: Because of the hardening? Did it work before we started?

These are time wasting situations

Let’s begin.

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Physical Security

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Physical Security

We assume that physical security is in place.

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OS Installation

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OS Installation

No system upgrades Why? Too many grey areas ONLY clean installations

Two partitions (we shall be using one) 01 system files 02 web applications

Strong administrative passwords Rainbow attacks make 8 character passwords trivial to break

Only install necessary components

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OS Installation

Use a static IP instead of DHCP if possible (one less service)

If there are multiple servers in the DMZ, consider making a DMZ domain from which critical servers will inherit their baseline GPOs.

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Proof of concept scan

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Proof of concept scanWindows 2003 v. Windows 2000

Why bother using windows 2003? More secure by default.

Can Windows 2000 be as secure? Yes. It requires work.

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Proof of concept scanWindows 2003 v. Windows 2000

We will use standard tools to inspect a default Windows 2003 installation.

Tools to use: Nmap. Scans to perform:

Nmap –sS –P0 –O –p1-65535 Nmap –sS –P0 –O –g 53 –p 1-65535 Nmap –sT –P0 –O –p1-65535

NStealth

Windows 2003: xx.xx.xx.xx

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Local Security Settings

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PoliciesLocal Security Settings

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PoliciesAccount Policies

Never use dictionary words. Never reuse old passwords by altering only one digit. Never choose passwords based on pets, habits, likes or

dislikes. One must never be able to identify a password by looking at the things on your desk.

Use upper- and lowercase with symbols and numbers. Choose passwords based on phrases:

Th15 comput€r i5 prot€cted by a str0ng p@ssword

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PoliciesAccount Policies: password Policy

Enforce Password History: 24 Maximum Password Age: 42 days Minimum Password Age: 2 days Minimum Password Length: 14 Complexity requirements: Enabled Use Reversible Encryption: Disabled

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PoliciesAccount Policies: Account Lockout Policy

Account Lockout Duration: 15 Minutes Account Lockout Threshold: 10 invalid attempts Reset Lockout Counter: 15 Minutes

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Services

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Services

What services does a web-server need? Are you sure they are needed?

YES: secure them NO: remove them

This is the hardest to get right

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Or…

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System SettingsIsn’t there a quicker way to change system settings?

Yes. Meet the ”Security Analysis and Configuration” snap-in

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System SettingsSecurity Analysis and Configuration

Run mmc File Add/Remove Snap-in Add Security Configuration and Analysis Add Right Click on Security Analysis and Configuration Open

Database Choose a File Name Open Navigate to ”High Security Baseline.inf” Open Right Click on Security Analysis and Configuration Analyse

Computer Now… Save the log to your desktop

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User Accounts

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User AccountsSecuring Well known User Accounts

Rename all built-in accounts: Administrator Guest

Why? Everyone knows the names of these two Windows accounts. 50% of a brute force attack is already common knowledge.

The descriptions should also be altered.

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User AccountsSecuring Well known User Accounts

Assign strong passwords to these accounts Th15 1s @ v€ry st0ng p@s5word don’t y0u th1nk?

Disable default guest accounts (if not already done by default)

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IP Policies

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IP PoliciesStructure

IP Filter advice: give your rules good names. Examples might look like this: <POLICY> <DIRECTION> <SERVICE> Permit INBOUND HTTP(S) Permit OUTBOUND SSH Permit OUTBOUND DNS Permit OUTBOUND HTTP(S) Deny BIDIRECTIONAL ALL

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IP PoliciesExample scenario

A web server might look similar to this: Permit INBOUND:

HTTP HTTPS? TS?

Permit OUTBOUND: HTTP HTTPS DNS

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IP PoliciesLocal Security Settings

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IP PoliciesLets get started

Create IP Security Policy… Name: Secure Web Uncheck “Activate the default response rule” Check “Edit Properties” Uncheck “Use Add Wizard”

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IP PoliciesBasic rules

Create 4 rules Deny BIDIRECTIONAL ALL Permit INBOUND HTTP(S) Permit OUTBOUND HTTP(S) Permit OUTBOUND DNS

When you’re done, assign your new policy

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IP PoliciesLets look at the results

Tools needed: NMap

Exercise Groups of two or three Choose which computer will perform the scan Un-assign IP Policies as they also block outboud traffic Perform the following port scans:

Nmap –sS –P0 –O –p1-65535 Nmap –sS –P0 –O –g 53 –p 1-65535 Nmap –sT –P0 –O –p1-65535

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File Permissions

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PermissionsAssigning correct NTFS permissions

CGI files: .EXE, .DLL, .CMD, .PL Administrators: Full Control System: Full Control IUSR_SERVER: Read & Execute, Read

Script Files: .ASPX, .ASP, .PHP Administrators: Full Control System: Full Control IUSR_SERVER: Read & Execute, Read

Include Files: .INC, .SHTML, .SHTM Administrators: Full Control System: Full Control IUSR_SERVER: Read & Execute, Read

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PermissionsAssigning correct NTFS permissions

Static Files: .HTML, .HTM, .TXT, .GIF, .JPG Administrators: Full Control System: Full Control IUSR_SERVER: Read

Data Files: .MDB Administrators: Full Control System: Full Control IUSR_SERVER: Read, Write, Read & Execute, Modify

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Hardening IIS

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Hardening IIS

Web server extensions Application Debugging Custom Errors HTTP Verbs URL Scan Logging

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Web server ExtensionsPredefined Web Service Extensions

Everything is turned off by default A default IIS 6.0 installation will only run sites with static

pages, .HTML, .HTM.

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Web server ExtensionsPredefined Web Service Extensions (cont.)

Active Server Pages ASP.NET version 1.1.4322 FrontPage Server Extensions 2002 Internet Data Connector Server-Side Includes WebDAV

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Application DebuggingStop IIS from sending error messages to clients

Stop applications from sending debugging details to clients: Right click on your web site in the IIS manager Home Directory Configuration App Debugging Check ”Send text error to client” and leave the box blank

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Custom ErrorsRedirect to a custom error page when error occur

Send custom error pages to clients for HTTP 500’s, 404’s: Right click on your web site in the IIS manager Custom Errors double click on 500 Message Type: URL URL: /<LOCATION OF CUSTOM PAGE>

Make certain that error 500 messages don’t get sent to the browser!

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HTTP VerbsLimit access to HTTP Verbs

Remove all un-needed HTTP verbs from each application: Generally required: GET, HEAD, POST

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URL ScanUrl filtering

What is URL Scan? What can it do?

Enable/disable HTTP verbs Disable HTTP headers Enable/disable specific file extensions Disable character sequences Remove/alter the server header Restrict header lengths

Questions concerning URL Scan?

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URL ScanUrl filtering

How does it work: Configuration File Installation Fine tuning

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LoggingConfiguring Logging

Create seperate logs for each site Log Folder Permissions

Administrators: Full Control System: Full Control IUSR_SERVER: Read, Write, Modify, List Folder Contents, Read & Execute

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Additional Hardening

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Additional Hardening

Uninstallable Components Special Binaries

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Uninstallable Components

1. Load “%systemroot%\inf\sysoc.inf” into notepad2. Replace ”hide” with ””3. Run Add/Remove Applications4. Remove any unwanted/ unneeded components (be careful!)

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Special Binaries

Several executables exist on a standard Windows 2000 installation that could become rather useful to an attacker

Special access rights need to be set on all of these executables

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Special Binaries (cont.)

Uncheck ”Allow inheritable permissions from parent to propagate this object”.

Remove all users from the name list, including SYSTEM.

Assign ”Full Control” to a user that is to be used to access these files – an administrator.

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Special Binaries (cont.)

rsh.exe, secfixup.exe, telnet.exe, tftp.exe, ipconfig.exe, nbtstat.exe, netstat.exe, ping.exe, qbasic.exe, rdisk.exe, regdit32.exe, net.exe, nslookup.exe, posix.exe, rcp.exe, regedit.exe, rexec.exe, tracert.exe, command.com, regedit.exe, os2.exe, os2ss.exe, arp.exe, at.exe, atsvc.exe, cacls.exe, cmd.exe, debug.exe, edit.com, edlin.exe, finger.exe, ftp.exe, xcopy.exe, os2srv.exe, cscript.exe, wscript.exe, iisreset.exe, route.exe, runonce.exe, syskey.exe

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What have we learned today?

Physical Security OS Installation Account Policies Local Policies Services User Accounts IP Policies- Permissions Hardening IIS Additional Hardening

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