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 arent 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 its already running. OR Dump running services from a typical baseline the command line 1. 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 NameDescriptionRecommended State AlerterRaises administrative alerts for selected users and computers. Disabled Application Layer Gateway Service Required if you use Internet Connection Sharing (ICS) or XPs included Internet Connection Firewall to connect to the Internet. Automatic if using ICS; disabled if not. Application ManagementUsed to assign, publish, and remove software through Group Policy. Disabled unless you participate in an Active Directory domain. Automatic Updates ServicesUsed to check if any critical updates are available for download. Requires Cryptographic to be running. Automatic if you dont 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. ClipBookEnables the ClipBook Viewer to create and share data to be viewed by remote computers. Disabled. COM+ Event SystemProvides automatic distribution of events to subscribing programmatic components. Disabled. COM+ System ApplicationProvides automatic distribution of events to subscribing programmatic components. Disabled. Computer BrowserMaintains an up-to-date list of computers on your network, and supplies the list to programs that request it. Disabled. Cryptographic ServicesConfirms 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 ClientManages network configuration by registering and updating IP addresses and DNS server information. Automatic if required; disabled if not.
Common Services to Review -2 Service NameDescriptionRecommended State Distributed 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 ClientResolves and caches DNS names. The DNS client service must be running on every computer that will perform DNS name resolution. Automatic. Error Reporting ServiceCalls home to Microsoft when errors occur.Disabled Event LogLogs event messages issued by programs and Windows. This can be useful in diagnosing problems. Automatic Fax ServiceEnables you to send and receive faxes. Disabling this service will render the computer unable to send or receive faxes. Disabled; or dont install from distribution media. TelephonyProvides 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 ServiceNot available on Windows XP Home. Not installed by default on Windows XP Pro. Enables FTP service. Disabled; or dont install from distribution media. Help and SupportRequired for Microsofts online help documents.Automatic
Common Services to Review -3 Service NameDescriptionRecommended State Human Interface Device Access If all your devices function, then disable it.Disabled. IIS AdminNot available on Windows XP Home. Not installed by default on Windows XP Pro. Allows administration of Internet Information Services (IIS). Disabled; or dont install from distribution media. IMAPI CD-Burning COM Service Used for the drag-and-drop CD-burn capability. Youll need this service to burn CDs. Automatic ndexing ServiceIndexes 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 ServicesManages IP security (IPsec) policy, starts the Internet Key Exchange (IKE), and coordinates IPsec policy settings with the IP security driver. Disabled. Logical Disk ManagerWatches 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 items description.Manual. Message QueuingA messaging infrastructure and development tool for creating distributed messaging applications for Windows. Disabled; or dont install from distribution media.
Common Services to Review -4 Service NameDescriptionRecommended State Message Queuing TriggersRequired only if you use Message Queuing Service.Disabled; or dont install from distribution media. MessengerSends 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 ConnectionsManages objects in the Network and Dial-Up Connections folder, in which you can view both network and remote connections. Automatic. Network DDEUseless service unless you use remote ClipBook.Disabled. Network DDE DSDMSee previous items 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.
Common Services to Review -5 Service NameDescriptionRecommended State Performance Logs and AlertsConfigures performance logs and alerts.Disabled. Plug & PlayEnables 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 SpoolerQueues and manages print jobs locally and remotely. If you dont have a printer attached, then disable. Automatic. Protected StorageProvides protected storage for sensitive data, such as private keys, to prevent access by unauthorized services processes or users. Disabled. QoS RSVPProvides 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
Common Services to Review -6 Service NameDescriptionRecommended State Remote Procedure Call Locator Manages the RPC name service database.Disabled Remote Registry ServiceNot available on Windows XP Home. Allows users to connect to a remote registry and read and/or write keys to itproviding they have the required permissions. Disabled Removable StorageManages 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 ListenerNot installed by default.Disabled; or dont install from distribution media. Routing and Remote AccessOffers routing services in local area and wide area network environments. Disabled; or dont install from distribution media. Secondary LogonAllows you to run specific tools and programs with different permissions than your current logon provides. Automatic Security Accounts ManagerStartup of this service signals other services that the Security Accounts Manager subsystem is ready to accept requests. Automatic ServerProvides 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 youre sharing files; disabled if not. Shell Hardware DetectionUsed 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 networkDisabled; or dont install from distribution media.
Common Services to Review -7 Service NameDescriptionRecommended State Simple TCP/IP ServicesImplements support for a number of IP protocols.Disabled; or dont install from distribution media. Smart CardManages 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 HelperProvides support for earlier smart card readers attached to the computer. Disabled unless using a smart card reader. SNMP ServiceAllows Simple Network Management Protocol (SNMP) requests to be serviced by the local computer. Disabled; or dont install from distribution media. SNMP Trap ServiceReceives trap messages generated by local or remote SNMP agents and forwards the messages to SNMP management programs running on the computer. Disabled; or dont install from distribution media. SSDP Discovery ServiceUsed to locate UPnP devices on your home network. Disabled System Event NotificationTracks system events such as Windows logon network and power events. Disabled System Restore ServiceCreates system snapshots or restore points for returning to at a later time. Disabled Task SchedulerEnables 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 ServerUsed for setting up a local UNIX print server.Disabled; or dont install from distribut ion media.
Common Services to Review -8 Service NameDescriptionRecommended State TelephonyProvides 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. TelnetAllows a remote user to log on to the system and run console programs by using the command line. Disabled; or dont install from distribution media. Terminal ServicesProvides a multisession environment that allows client devices to access a virtual Windows 2000 Professional desktop session and Windows-based programs running on the server. Disabled; or dont install from distribution media. ThemesUsed 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 ManagerAs 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 CopyUsed in conjunction with the MS Software Shadow Copy Provider Service. Microsoft Backup uses these services. Disabled WebClientDisable this for security reasons.Disabled Windows AudioUsed for some scanners and cameras. If, after disabling this service, your scanner or camera fails to function properly, enable this service. Automatic
Common Services to Review -9 Service NameDescriptionRecommended State Windows 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 InstallerInstalls, 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 TimeSets the computer clock. W32Time maintains date and time synchronization on all computers running on a Microsoft Windows network. Automatic Wireless Zero ConfigurationAutomatic configuration for wireless network devices. Disabled WMI Performance AdapterOptimizes the speed of WMI queries.Disabled WorkstationProvides 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. Disabled; or dont install from distribution media.
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 services 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 dont do it.
Do not allow network access to service accounts This means dont 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 accounts 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.
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 isnt part of that services profile Service Hardening Active protection File system Registry Netwo rk
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 AliceBob Session 1Session 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
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 system Service: 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 its 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 Time Server
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) 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 services process token by SCM when the service is started Per-service SID can be used to protect service resources Service resources can be ACLd 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\ directory; by adding service SID to directorys DACL, the service can write to its log files even if its 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 (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 doesnt 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 Access Administrators 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 Access Service 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, wont 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
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
Applications Wont Run Biggest problem with desktops Usually legacy applications that are unaware of security contexts Symptom: Runs as administrator, fails as Normal User Doesnt 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 Wont 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 Wont 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 Sysinternals 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 Solution Configuration Management of Security Templates Layer security template deltas 1. Start with standard MSS template 2. Overlay Customer Delta from security standard 3. 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 Dont 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 Dont Capture all Security Related Settings Extend choices through use of ADMs 1. 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