Services. Reasons to Review Services One of the easiest ways for to exploit holes in your system is through open services - especially in windows XP,

Services

Reasons to Review Services

One of the easiest ways for to exploit holes in your system is through open services - especially in windows XP, 2000, and earlier systems.

Unnecessary services should be disabled and/or managed.

Removal of services will cause a performance enhancement because stagnant programs aren’t taking up available resources.

Full security audit of your services can reveal some interesting details about your machine. Viruses have been masquerading as

services listed in the Task Manager, making them harder to detect, clean, and prevent.

Windows XP

To manage services on your computer, do the following:

1. Right-click My Computer, and choose Manage.2. Expand the Services & Applications tab, and select

Services.3. Double-click a service.4. Under Startup Type, select Manual to disable a

service from automatically starting upon computer bootup. Click the Stop button to stop the service if it’s already running.

ORDump running services from a typical baseline the

command line1. Net start > services.txt

Review Active Services

Study results for the following: Which services require an account to start?

Will a local account work? Narrowly define permissions account requires Audit for activity against that account in the

future Which services are unnecessary?

Start with Security Guides list of services to disable

Maintain settings in security template

Common Services

Following pages contain a nearly complete list of all services that ship with Windows XP and the recommended state that each should be in on your computer, assuming normal office functions are being performed on the machine.

Common Services to Review

Service Name Description Recommended StateAlerter Raises administrative alerts for selected

users and computers. Disabled

Application Layer Gateway Service

Required if you use Internet Connection Sharing (ICS) or XP’s included Internet Connection Firewall to connect to the Internet.

Automatic if using ICS; disabled if not.

Application Management

Used to assign, publish, and remove software through Group Policy.

Disabled unless you participate in an Active Directory domain.

Automatic Updates Services

Used to check if any critical updates are available for download.

Requires Cryptographic to be running. Automatic if you don’t wish to use Windows Update manually.

Background Intelligent Transfer Service

Used by Windows Update to transfer data in the background using otherwise idle available network bandwidth.

Disabled.

ClipBook Enables the ClipBook Viewer to create and share data to be viewed by remote computers.

Disabled.

COM+ Event System Provides automatic distribution of events to subscribing programmatic components.

Disabled.

COM+ System Application

Provides automatic distribution of events to subscribing programmatic components.

Disabled.

Computer Browser Maintains an up-to-date list of computers on your network, and supplies the list to programs that request it.

Disabled.

Cryptographic Services Confirms signatures of Windows files. Required for Windows Update to function in manual and automatic mode, and required for Windows Media Player as well.

Automatic.

DHCP Client Manages network configuration by registering and updating IP addresses and DNS server information.

Automatic if required; disabled if not.

Common Services to Review -2

Service Name Description Recommended StateDistributed Link Tracking Client

Maintains links between the NTFS file system files within a computer or across computers in a network domain.

Disabled.

Distributed Transaction Coordinator

Coordinates transactions that are distributed across multiple computer systems and/or resource managers, such as databases, message queues, file systems, or other transaction-protected resource managers.

Disabled.

DNS Client Resolves and caches DNS names. The DNS client service must be running on every computer that will perform DNS name resolution.

Automatic.

Error Reporting Service Calls home to Microsoft when errors occur. Disabled

Event Log Logs event messages issued by programs and Windows. This can be useful in diagnosing problems.

Automatic

Fax Service Enables you to send and receive faxes. Disabling this service will render the computer unable to send or receive faxes.

Disabled; or don’t install from distribution media.

Telephony Provides Java Telephony API (TAPI) support for programs that control telephony devices and IP-based voice connections on the local computer and through the LAN on servers that are also running the service.

Disabled unless required.

FTP Publishing Service Not available on Windows XP Home. Not installed by default on Windows XP Pro. Enables FTP service.


Help and Support Required for Microsoft’s online help documents.

Automatic


Service Name Description Recommended StateHuman Interface Device Access

If all your devices function, then disable it. Disabled.

IIS Admin Not available on Windows XP Home. Not installed by default on Windows XP Pro. Allows administration of Internet Information Services (IIS).


IMAPI CD-Burning COM Service

Used for the “drag-and-drop” CD-burn capability. You’ll need this service to burn CDs.

Automatic

ndexing Service Indexes contents and properties of files on local and remote computers and provides rapid access to files through a flexible querying language.

Disabled.

Internet Connection Firewall and Internet Connection Sharing

Provides network address translation (NAT), addressing and name resolution services for all computers on your home or small-office network through a dial-up or broadband connection.

Automatic if sharing connection, disabled if not required.

IPSEC Services Manages IP security (IPsec) policy, starts the Internet Key Exchange (IKE), and coordinates IPsec policy settings with the IP security driver.

Disabled.

Logical Disk Manager Watches Plug & Play events for new drives to be detected and passes volume and/or disk information to the Logical Disk Manager Administrative Service to be configured. If disabled, the Disk Management snap-in display will not change when disks are added or removed.

Manual.

Logical Disk Manager Administrative Service

See previous item’s description. Manual.

Message Queuing A messaging infrastructure and development tool for creating distributed messaging applications for Windows.



Service Name Description Recommended StateMessage Queuing Triggers

Required only if you use Message Queuing Service.


Messenger Sends and receives messages to or from users and computers, or those transmitted by administrators or by the Alerter Service.

Disabled.

MS Software Shadow Copy Provider

Used in conjunction with the Volume Shadow Copy Service. Microsoft Backup uses these services.

Enabled.

NetMeeting Remote Desktop Sharing

Allows authorized users to remotely access your Windows desktop from another PC over a corporate intranet by using NetMeeting.

Network Connections Manages objects in the Network and Dial-Up Connections folder, in which you can view both network and remote connections.

Automatic.

Network DDE Useless service unless you use remote ClipBook.

Disabled.

Network DDE DSDM See previous item’s description. Disabled.

Network Location Awareness (NLA)

Required for use with the Internet Connection Sharing Service (server only).

Disabled unless running ICS or ICF.

NTLM Security Support Provider

Enables users to log on to the network using the NTLM Authentication Protocol. If this service is stopped, users will be unable to log on to the domain and access services. NTLM is used mostly by Windows versions prior to Windows 2000.

Automatic.


Service Name Description Recommended StatePerformance Logs and Alerts

Configures performance logs and alerts. Disabled.

Plug & Play Enables a computer to recognize and adapt to hardware changes with little or no user input.

Automatic.

Portable Media Serial Number

Retrieves serial numbers from portable music players connected to your computer.

Disabled.

Print Spooler Queues and manages print jobs locally and remotely. If you don’t have a printer attached, then disable.

Automatic.

Protected Storage Provides protected storage for sensitive data, such as private keys, to prevent access by unauthorized services processes or users.

Disabled.

QoS RSVP Provides network signaling and local, traffic-control functionality.

Disabled unless required by your network administrator.

Remote Access Auto Connection Manager

Creates a connection to a remote network whenever a program references a remote DNS or NetBIOS name or address.

Disabled.

Remote Access Connection Manager

Creates a network connection. Automatic if using Dial-Up Networking; disabled otherwise

Remote Desktop Help Session Manager

Manages and controls Remote Assistance. Disabled

Remote Procedure Call (RPC)

Provides the endpoint mapper and other miscellaneous RPC services.

Automatic


Service Name Description Recommended StateRemote Procedure Call Locator

Manages the RPC name service database. Disabled

Remote Registry Service Not available on Windows XP Home. Allows users to connect to a remote registry and read and/or write keys to it—providing they have the required permissions.

Disabled

Removable Storage Manages removable media drives and libraries. This service maintains a catalog of identifying information for removable media used by a system, including tapes, CDs, and so on.

Disabled

RIP Listener Not installed by default. Disabled; or don’t install from distribution media.

Routing and Remote Access

Offers routing services in local area and wide area network environments.


Secondary Logon Allows you to run specific tools and programs with different permissions than your current logon provides.

Automatic

Security Accounts Manager

Startup of this service signals other services that the Security Accounts Manager subsystem is ready to accept requests.

Automatic

Server Provides RPC support and file print and named pipe sharing over the network. The Server Service allows the sharing of your local resources (such as disks and printers) so that other users on the network can access them.

Automatic if you’re sharing files; disabled if not.

Shell Hardware Detection

Used for the autoplay of devices like memory cards, some CD drives, and so on.

Disabled unless required.

Simple Mail Transport Protocol (SMTP)

Transports email across the network Disabled; or don’t install from distribution media.


Service Name Description Recommended StateSimple TCP/IP Services Implements support for a number of IP

protocols. Disabled; or don’t install from distribution media.

Smart Card Manages and controls access to a smart card inserted into a smart card reader attached to the computer.

Disabled unless using a smart card reader.

Smart Card Helper Provides support for earlier smart card readers attached to the computer.

Disabled unless using a smart card reader.

SNMP Service Allows Simple Network Management Protocol (SNMP) requests to be serviced by the local computer.


SNMP Trap Service Receives trap messages generated by local or remote SNMP agents and forwards the messages to SNMP management programs running on the computer.


SSDP Discovery Service Used to locate UPnP devices on your home network.

Disabled

System Event Notification

Tracks system events such as Windows logon network and power events.

Disabled

System Restore Service Creates system snapshots or restore points for returning to at a later time.

Disabled

Task Scheduler Enables a program to run at a designated time.

Disabled unless absolutely required.

TCP/IP NetBIOS Helper Service

Enables support for NetBIOS over TCP/IP (NetBT) service and NetBIOS name resolution. Only required if you need to share files with others.

Disabled unless sharing is enabled.

TCP/IP Printer Server Used for setting up a local UNIX print server.

Disabled; or don’t install from distribut ion media.


Service Name Description Recommended StateTelephony Provides Telephony API (TAPI) support for

programs that control telephony devices and IP-based voice connections on the local computer and through the LAN on servers that are also running the service.

Disabled.

Telnet Allows a remote user to log on to the system and run console programs by using the command line.


Terminal Services Provides a multisession environment that allows client devices to access a virtual Windows 2000 Professional desktop session and Windows-based programs running on the server.


Themes Used to display all those new XP themes and colors on your desktop. Lots of space needed.

Automatic or manual, depending on your preferences.

Uninterruptible Power Supply (UPS)

Manages communications with a UPS connected to the computer by a serial port.

Disabled unless using a UPS.

Universal Plug & Play Device Host

Used in conjunction with SSDP Discovery Service, it detects and configures UPnP devices on your home network.

Disabled

Upload Manager As with BITS, this service manages file transfers between clients and servers on the network. This service is NOT required for basic File and Print sharing.

Disabled

Volume Shadow Copy Used in conjunction with the MS Software Shadow Copy Provider Service. Microsoft Backup uses these services.

Disabled

WebClient Disable this for security reasons. Disabled

Windows Audio Used for some scanners and cameras. If, after disabling this service, your scanner or camera fails to function properly, enable this service.

Automatic


Service Name Description Recommended StateWindows Image Acquisition (WIA)

Used for some scanners and cameras. If, after disabling this service, your scanner or camera fails to function properly, enable this service.

Disabled

Windows Installer Installs, repairs, or removes software according to instructions contained in MSI files provided with the applications.

Manual

Windows Management Instrumentation (WMI)

Provides system management information. WMI is an infrastructure for building management applications and instrumentation shipped as an integral part of the current generation of Microsoft operating systems.

Automatic

Windows Management Instrumentation Driver Extension

Tracks all of the drivers that have registered WMI information to publish.

Manual

Windows Time Sets the computer clock. W32Time maintains date and time synchronization on all computers running on a Microsoft Windows network.

Automatic

Wireless Zero Configuration

Automatic configuration for wireless network devices.

Disabled

WMI Performance Adapter

Optimizes the speed of WMI queries. Disabled

Workstation Provides network connections and communications. If this service is turned off, no network connections can be made to remote computers using Microsoft Networks.

Automatic

World Wide Web Publishing Service

Provides HTTP services for applications on the Windows platform.


Providing a Secure Configuration for Services

While disabling unnecessary services is a fundamental step to hardening Windows, there are some other necessary items to accomplish to further secure the services that remain and any services that you may add in the future.

Give strong passwords to service accounts.

When you install applications that require services to be run, you are typically given the option to choose an account under which the service is to be run. Use 15+ character passwords, and

remember that you must set these passwords both in: Active Directory Users and

Computers or Computer Management (depending on your operating environment)

and The Log On tab of the service’s

property sheet.

Never let users log on using service accounts

This most particularly applies to the Administrator account Never assign the

Administrator account to a service, and

Never distribute any service account name and password to any users.

There is absolutely no reason to do so, and if users can access systems in these contexts, they can wreak havoc

Just don’t do it.

Do not allow network access to service accounts

This means don’t create domain accounts for services unless no other option exists; Wherever possible, use a local

account on the server where the service is located.

Also, check the Deny Access to this Computer from the Network right within the service account’s property sheet to eliminate network access for that account.

Use least privilege for service accounts

Windows XP includes a set of built-in accounts, collectively called the Network Service and Local Service, Specifically designed to be

used for services that require different amounts of network connectivity.

Use these where possible to decrease the attack surface of services.

Post XP Windows Services Hardening

Windows Service Hardening

Windows services are profiled for allowed actions to the network, file system, and registry

Designed to block attempts by malicious software to make a Windows service write to an area of the network, file system, or registry that isn’t part of that service’s profile

Service Hardening

Activeprotection

File system

Registry

Network

What is Service Hardening?

High privileged services when exploited allow attacker to gain unbounded control on the computer

Hardening a service means limiting damage to the system even if a service is compromised

Can not prevent a service from being compromised but provides additional layer of protection Based on principle of

defense-in-depth

Service Hardening

Service hardening is one of many new security mechanisms in Windows Vista and in Windows 7

The next generations of Windows server, including W2K8

It more difficult for service exploits to do damage

Why Service Hardening?Issues with earlier versions of Windows

Related Background

LogOn

Session 0

“Alice”“Bob”

“Bob”

Session 1 Session 2

“Alan”

“Alice”“Alan”

Session• Mechanism to

support multiple interactive users logging on to the system simultaneously

• Each user (remote or local) feels as if she is using the system locally

Related Background

Window Messages Communication mechanism

between application windows or system and application windows

E.g. when system time is changed, system sends WM_TIMECHANGE to all application windows on desktop.

Privilege Right of an account to perform

various system-related operations on the local computer

Example: shutting down the system, changing system time etc

Issues with earlier versions of Windows

Shared Session 0 Privilege Issue No Service Isolation

Shared Session 0

Services and user applications for console user run in the same session (session 0)

Application windows in same session can freely send window messages to each other.

Shared Session 0 ( contd)

Shatter Attack Freelance security consultant Chris

Paget discovered flaw in Windows messaging named as “Shatter Attack”

A low privilege application window may exploit a vulnerability in high privilege application window by means of window messaging

It is possible due to Shared Session 0

Shatter Attack

WM_TIMER abuse

SendMessage( WM_TIMER, BadFunc )

void BadFunc(){ FormatDisk();}

Desktop

Window 1 Window 2

Privilege Issue

Services automatically gain all privileges of account they are running in

Services cannot specify set of privileges required

Lack of granular control over privileges Services run with

unnecessary high privileges

Local systemService:

Disk Manager

Garbage Collector

Privileges:

Load driver

Shut Down

Back Up

No Service Isolation

Services do not have their individual identity Identity of a service is tied up with

account it’s running in E.g. When Web Server is granted access to

database, Time Server also gains access to the database

`

Web Server

Database

Account:LocalService Account:LocalService

Time Server

Service Hardening in Vista/7

Service Hardening in Vista/7 Session 0 Isolation

Session 0 is assigned exclusively to services and the session is made non-interactive

Fostering principle of “least privileges” Services can now specify required

set of privileges Per-service Security Identifier (SID) Network Access Restriction

Session 0 Isolation

No More Share Session 0 Session 0 is assigned

exclusively to services and the session is made non-interactive

User applications run in session 1 and higher

Services are isolated from user applications to avoid shatter attacks

35

Fostering principle of “least privileges”

Services can now specify required set of privileges Services are no longer required

to run with all the privileges associated with the accounts they run in

Provides granular control Service Control Manager (SCM)

removes all the privileges that are not specified as required privileges from the process token If no required privileges are

specified, SCM assumes that service needs all the privileges

If service requires privileges not present in the process token, service is not started

36

Per-service Security Identifier (SID)

Per-service Security Identifier (SID) Each service installed on

Longhorn/Vista is assigned a SID Per-service SID is based on the

service name and is unique to that service on the computer

When per-service SID is enabled for a service, it is added to the service’s process token by SCM when the service is started

Per-service SID can be used to protect service resources Service resources can be ACL’d

with service SID to grant access exclusively to that service

It provides more granularity and service isolation

37

Per-service Security Identifier (SID)

Per-service SID can be used to gain access to certain objects normally accessible to administrative privileges By virtue of service SID, services

can run in low privilege account and can still access certain objects that are accessible only to high privilege accounts

e.g. A service running in low privilege might need write-access to its log files stored in “Program Files\<application_dir>”directory; by adding service SID to directory’s DACL, the service can write to its log files even if it’s running with low privileges

38

Network Access Restriction

Service network restriction are implemented with per-service SIDs

Longhorn/Vista firewall has been enhanced to support service network restriction

39

Network Access Restriction (Continued)

Services can add firewall rule to specify communication protocol, ports and direction of the traffic e.g. A service can add a rule to restrict its network access on TCP port 10000 for outbound communication Integrated firewall in Vista/Longhorn will block all other type of network access

40

Weakness

With reduced privileges, certain Services may not function correctly Extensive research is

required to determine exact required privileges

Cannot completely avoid the damage caused by vulnerability exploit

May ask for design level changes

Strength

Adds as second layer of protection

Reduces damage of vulnerability exploit to a great extent

Fosters better security practices

Access Control Lists

Access Control Lists (ACLs)

Extensive ACL edits have been done in the past to harden systems Starting with NT and 2000 NSA led the way File and Registry Permissions Not as necessary with Windows 2003

and beyond (if it doesn’t have to support legacy trusts); Security Guide does not recommend ACL edits for W2K3 or newer

Rough summary of typical edits: Substitute Authenticated Users for

Everyone (Anonymous SID exposure) Remove unused or more exposed

groups such as Power Users from all ACLs

Remove Batch or Interactive ACLs on particularly vulnerable executables

Limit Access Administrator and

Service Accounts

Limit and Control Access All the protection in the world can

be circumvented by poor Administrator and Service Account maintenance and monitoring

Most attacks are internal Most users and even administrators

do NOT require full administrator status to get their jobs done Example: developers can do most of

their development logged in as a Normal User, and should be encouraged to do so

Use of Run As to elevate privileges ONLY when required for a specific task

Limit and Control AccessAdministrators Train Administrators to use passwords

with more than 15 characters Phrases are easy to remember (spaces

allowed in 2000 and 2003) Make sure all Administrators have at

least two accounts Normal User for daily tasks (e-mail, word

processing) Separate account with Administrator

permissions (audit this account closely) Consider using local groups on

individual servers to limit who can administrate

Limit and Control AccessService Accounts Use passwords with more than 15

characters and extended characters (Alt + Numbers)

Limit the damage if the account is compromised See if a local account can be used instead

of a domain account However, won’t work for accounts that

must communicate with other servers SQL agents, for instance, often require

connectivity to other servers Narrow permissions of what the account

can do Audit these accounts closely

Workstation Applications

How to Choose Secure Applications

Keep the focus on the lowest common denominator: what must be on every desktop? Every server?

Research for security breaches on all software planned for installation (not just the operating system)

Gather the necessary updates and patches Windows Update Catalog Microsoft Security Alerts Vendor sites for third-party applications Forums and sites like

Choosing Components

Choose as few components as possible

Set to No (do not install) even if that is the default (for accountability later)

Avoid installing IIS on the workstations

Avoid commonly attacked components, such as FTP, Simple TCP/IP, and SNMP

Commonly Encountered Problems

Applications Won’t Run

Biggest problem with desktops

Usually legacy applications that are unaware of security contexts Symptom: Runs as

administrator, fails as Normal User

Doesn’t understand profiles

Often due to more restrictive file and/or registry permissions in the new OS

Occasionally due to hard-coded calls to previous operating system APIs

Applications Won’t Run (cont)

Windows XP SP2 introduced new, secure-by-default changes RPC Interfaces no longer

allow anonymous remote connections by default

DCOM Remote Launch and Activation limited to administrators by default

Windows Firewall on by default

Access to system services using RPC blocked by default

Solution Applications Won’t Run

Ideally, upgrade or re-develop, but this can be prohibitively expensive

Use Application Compatibility Toolkit on Windows XP Construct a custom SDB fix Work with Compatibility Modes to emulate other

operating systems Use Sysinternal’s regmon.exe and

filemon.exe to isolate permissions Develop a custom INF to loosen the necessary

settings Goal: Figure out the minimal settings

necessary to get the application running

Configuration Management of Security Templates Ongoing changes will be

inevitable, particularly to manage desktop application requirements

Security settings should evolve as the environment does Example: NT 4.0 trusts go

away Complexity and number of

settings makes this a challenge

Solution Configuration Management of Security Templates

Layer security template deltas1. Start with standard MSS template 2. Overlay Customer Delta from security

standard3. Overlay Application specific loosening of ACLs

Make it clear what was adjusted for each application

Can remove template if application goes away later

Merge everything at the end; but maintain original files to provide accountability

Auditors receive deltas with justifications for the changes; much faster certification

Challenge: INFs Don’t Capture all Security Related Settings Security Template INF files have

limited scope Need to extend Group Policy

into other areas such as: Secure e-mail settings Internet Explorer settings Windows Update client

settings Need to be able to transport

these settings to other systems easily

Solution: INFs Don’t Capture all Security Related Settings Extend choices through use of

ADMs1. Run Group Policy

(gpedit.msc)2. Right click Administrative

Templates, choose Add/Remove Templates, pick the ADM file (e.g. Outlook ADM file)

Can be added as part of the build (locally) OR

Distributed via GPOs and AD Can add custom settings

Rollback Security Settings

Need to be able to confirm whether a reported problem is due to the security templates

If Access Control List (ACL) edits have been made, these “tattoo” the system permanently, even when a GPO is used How to roll back to out-of-the-

box permissions? Need to be able to do this on a

standalone system

Solution Rollback Security Settings Utilize INF files that are applied

as part of the original setup of the operating system: Defltwk.inf Defltdc.inf Delftsv.inf

Can be loaded like any other security template: via MMC Security Configuration Editor or secedit.exe

Microsoft Security Solutions (MSS) Security Guides Windows 2000 (W2K) Hardening Guide,

Windows XP, VISTA, 7, and W2k3, W2K8 Security Guides available

Threats and Countermeasures Security Templates Custom sceregvl.inf Guides coming out for all key Microsoft

enterprise systems, such as Exchange 2003

Best common sense, field tested source for security lockdowns

Secure Configuration Resources: Tools

Setup Manager Security Template Snap-In Security Configuration Editor

Snap-In Secedit.exe Group Policy Management

Console Security Configuration Wizard Application Compatibility Toolkit Sysinternals Regmon and

Filemon

Documents

Services. Reasons to Review Services One of the easiest ways for to exploit holes in your system is through open services - especially in windows XP,