Securing Windows web servers

Hardening Windows 2003 Web Servers

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

General Who 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

General Strategy: Creating a secure environment Secure current and/or new implementations of the Windows 2003 operating system

General Strategy: 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!!

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

General Prerequisites 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

General What 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

Hardening one step at a time Physical Security --------------------------------------- OS Installation ----------------------------------------- Account Policies ---------------------------------------- Local Policies ------------------------------------------- Services ------------------------------------------------ User Accounts ----------------------------------------- IP Policies------------- --------------------------------- Permissions -------------------------------------------- Hardening IIS ------------------------------------------ Additional Hardening ---------------------------------- Number of Weaknesses

Prerequisites What 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.

Physical Security We assume that physical security is in place.

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

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.

Proof of concept scan Windows 2003 v. Windows 2000 Why bother using windows 2003? More secure by default. Can Windows 2000 be as secure? Yes. It requires work.

Proof of concept scan Windows 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

Policies Local Security Settings

Policies Account 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

Policies Account 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

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

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

System Settings Isn’t there a quicker way to change system settings? Yes. Meet the ” Security Analysis and Configuration” snap-in

System Settings Security 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

User Accounts Securing 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.

User Accounts Securing 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)

IP Policies Structure 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

IP Policies Example scenario A web server might look similar to this: Permit INBOUND: HTTP HTTPS? TS? Permit OUTBOUND: HTTP HTTPS DNS

IP Policies Local Security Settings

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

IP Policies Basic 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

IP Policies Lets 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

Permissions Assigning 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

Permissions Assigning 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

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

Web server Extensions Predefined Web Service Extensions Everything is turned off by default A default IIS 6.0 installation will only run sites with static pages, .HTML, .HTM.

Web server Extensions Predefined Web Service Extensions (cont.) Active Server Pages ASP.NET version 1.1.4322 FrontPage Server Extensions 2002 Internet Data Connector Server-Side Includes WebDAV

Application Debugging Stop 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

Custom Errors Redirect 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!

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

URL Scan Url 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?

URL Scan Url filtering How does it work: Configuration File Installation Fine tuning

Logging Configuring 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

Additional Hardening Uninstallable Components Special Binaries

Uninstallable Components Load “%systemroot%\inf\ sysoc.inf” into notepad Replace ”hide” with ”” Run Add/Remove Applications Remove any unwanted/ unneeded components (be careful!)

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

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.

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

What have we learned today? Physical Security OS Installation Account Policies Local Policies Services User Accounts IP Policies- Permissions Hardening IIS Additional Hardening

Securing Windows web servers

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Securing Windows web servers