secure360 - extracting password from windows
DESCRIPTION
This presentation will provide an overview of common methods that can be used to obtain clear text credentials from Microsoft products such as Windows, IIS, and SQL Server. It also provides an overview of the proof of concept script used to recover MSSQL Linked Server passwords. Relevant blog links have been provided below. https://www.netspi.com/blog/entryid/215/decrypting-iis-passwords-to-break-out-of-the-dmz-part-1 https://www.netspi.com/blog/entryid/226/decrypting-iis-passwords-to-break-out-of-the-dmz-part-2 https://www.netspi.com/blog/entryid/221/decrypting-mssql-database-link-server-passwords More security blogs by the authors can be found @ https://www.netspi.com/blog/TRANSCRIPT
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INTRODUCTIONS
Who are we?
•Scott Sutherland
•Antti Rantasaari
What do we do?
•Network and application penetration testing
at NetSPI
GOAL
Provide a basic understanding of how passwords can be exposed on Windows systems
•What are the common controls?•What are their limitations?•How can we reduce risk?
OVERVIEW
How to steal credentials from Microsoft technologies:
• Password Storage
• Cleartext passwords
• Encrypted passwords
• Password hashes
• Authentication tokens
PASSWORD STORAGE
• Hashed passwords Used when cleartext password is not required later No key required, hashing process can’t be reversed
• Encrypted passwords Used when cleartext password will be required later Requires key to decrypt password Requires key management
• Encoded passwords Should not be used to protect passwords No key required to decode password
• Cleartext passwords – Don’t do that!
CLEARTEXT PASSWORDS
Why does it matter if passwords are stored or transmitted in cleartext?
• Vulnerabilities can provide read-only access to: OS files, backup files, and files shares Network traffic
• Passwords can then be used to access: Systems Applications / Databases Sensitive information
CLEARTEXT PASSWORDS
Why does it matter if passwords are stored or transmitted in cleartext?
• Vulnerability examples: File traversal Local file includes Excessive privileges on shares ARP MITM
CLEARTEXT PASSWORDS
Where can I find cleartext passwords?
• Mapped network drives – User files
• Configuration files
• Windows Registry
• Active Directory
• Websites
• Script files
• Log files
CLEARTEXT PASSWORDS
Mapped Network Drives
• Users have access to a ton of files shares
• File shares often have bad ACLs
• Users love to store password in files xls files doc files txt file etc…
CLEARTEXT PASSWORDS
Mapped Network Drives
• Easy to find passwords using: Find Grep Spider Notepad++ Etc…
CLEARTEXT PASSWORDS
Mapped Network Drives
Recommendations
• Review for password on at regular intervals
• Periodic audits of access controls on shares
• User awareness training
• Use of proper password storage
CLEARTEXT PASSWORDS
Configuration Files
• Sometimes config files are only accessible to administrators
• Most config files are accessible to all users Bad ACLs Access to backups
CLEARTEXT PASSWORDS
Configuration Files – Sysprep
• Files created to support the automation of large scale image roll outs
• Configuration settings
• Local and domain credentials
CLEARTEXT PASSWORDS
Configuration Files – Sysprep
• Files can be read by ANY user on the system
• There are many places they can be stored and used
CLEARTEXT PASSWORDS
Configuration Files – Sysprep
http://technet.microsoft.com/en-us/library/cc749415%28v=ws.10%29.aspx
Type LocationRegistry HKLM\System\Setup!UnattendFileFile %WINDIR%\Panther\UnattendFile %WINDIR%\Panther
FileRemovable read/write media in order of drive letter, at the root of the drive.
FileRemovable read-only media in order of drive letter, at the root of the drive.
File
windowsPE and offlineServicing passes:
\Sources directory in a Windows distribution
All other passes:
%WINDIR%\System32\SysprepFile %SYSTEMDRIVE%
CLEARTEXT PASSWORDS
Configuration Files – Sysprep
• Most of the time they are stored with no protection…
http://technet.microsoft.com/en-us/library/cc749415%28v=ws.10%29.aspx
CLEARTEXT PASSWORDS
Unattend and Sysprep Files
http://technet.microsoft.com/en-us/library/cc749415%28v=ws.10%29.aspx
Unattend.xml Example - Cleartext
…[snip]…
<OOBE> <HideEULAPage>true</HideEULAPage> <NetworkLocation>Work</NetworkLocation> <ProtectYourPC>1</ProtectYourPC> <SkipMachineOOBE>true</SkipMachineOOBE> <SkipUserOOBE>true</SkipUserOOBE> </OOBE> <UserAccounts> <AdministratorPassword>
<Value>Passw0rd</Value> <PlainText>true</PlainText> </AdministratorPassword> </UserAccounts> </component>
…[snip]…
CLEARTEXT PASSWORDS
Configuration Files – Sysprep
• Sometimes they are Base64 encoded…
http://technet.microsoft.com/en-us/library/cc749415%28v=ws.10%29.aspx
CLEARTEXT PASSWORDS
Unattend and Sysprep Files
http://technet.microsoft.com/en-us/library/cc749415%28v=ws.10%29.aspx
Unattend.xml Example – Base64 Encoded
…[snip]…
<OOBE> <HideEULAPage>true</HideEULAPage> <NetworkLocation>Work</NetworkLocation> <ProtectYourPC>1</ProtectYourPC> <SkipMachineOOBE>true</SkipMachineOOBE> <SkipUserOOBE>true</SkipUserOOBE> </OOBE> <UserAccounts> <AdministratorPassword>
<Value>UGFzc3cwcmQ=</Value> <PlainText>true</PlainText> </AdministratorPassword> </UserAccounts> </component>
…[snip]…
CLEARTEXT PASSWORDS
Configuration Files – Sysprep
• Sometimes they are Base64 encoded…
Base64 Encoding != Encryption
http://technet.microsoft.com/en-us/library/cc749415%28v=ws.10%29.aspx
CLEARTEXT PASSWORDS
Unattend and Sysprep Files
http://technet.microsoft.com/en-us/library/cc749415%28v=ws.10%29.aspx
CLEARTEXT PASSWORDS
Configuration Files – Sysprep
Recommendations
• Configure roll out scripts to remove the sysprep answer files like unattend.xml
• Additional notes: Prevent remote logins by local administrators
Manage systems with domain groups
CLEARTEXT PASSWORDS
Configuration Files – Web.config
• Used to store IIS web application configurations
• Often contain database passwords
• By default passwords are cleartext
CLEARTEXT PASSWORDS
Configuration Files – Web.config
• Typically stored at the webroot for each IIS site
• Usually can be read by all users on the system
CLEARTEXT PASSWORDS
Configuration Files – Web.config
Recommendations
• Encrypt passwords stored in web.config
aspnet_regiis.exe -pef "connectionStrings" c:\webapp
• Additional notes: Configure strong ACLs on file system
CLEARTEXT PASSWORDS
Configuration Files – Web.config
Recommendations
CLEARTEXT PASSWORDS
Basic Authentication
• Simple way to implement IIS authentication
• Uses Base64 encoding, NOT ENCRYPTION
• Credentials can be captured from network traffic over HTTP, or via man-in-the-middle over HTTPS
CLEARTEXT PASSWORDS
Basic Authentication
• Basic authentication over SSL is not that bad
• Very common to see it used over unencrypted HTTP connections
CLEARTEXT PASSWORDS
Basic Authentication
• Base64 Encoded
bmV0c3BpOlZlcnlTdHJvbmdBbmRIYXJkVG9HdWVzc1Bhc3N3b3Jk
• Easily decoded Base64
netspi:VeryStrongAndHardToGuessPassword
Microsoft ActiveSync (iPhone, etc.)
CLEARTEXT PASSWORDS
Basic Authentication
Recommendations
• Basic Auth is simple, but not often necessary
• Replace with Integrated Authentication to enforce authentication handshake
• Additional notes: Integrated Authentication can still be exploited, but it’s not as easy
CLEARTEXT PASSWORDS
Windows Registry
• Many applications store passwords in cleartext
• Easy to search for common strings to find passwords
• Windows also stores some passwords in cleartext Autologin username and password
CLEARTEXT PASSWORDS
Windows Registry - AutoLogin
• Used by many kiosk and POS systems
• Often stores autologin credentials in
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
"AutoAdminLogon"="1" "DefaultUserName"=“autoadmin" "DefaultPassword"=“!PassW0rd!" "DefaultDomainName"=“acme"
CLEARTEXT PASSWORDS
Windows Registry - AutoLogin
CLEARTEXT PASSWORDS
Windows Registry - AutoLogin
Recommendations
• Only use autologin when necessary
• If required, store credentials encrypted in LSASecrets
• Additional notes: The encrypted password can be recovered with administrative access to the system
http://technet.microsoft.com/en-us/sysinternals/bb963905.aspx
CLEARTEXT PASSWORDS
Active Directory
• UserComments
• Custom properties
CLEARTEXT PASSWORDS
Active Directory
Recommendations
• Don’t store cleartext passwords in active directory
• Audit Active Directory periodically for comments and custom objects that may contain passwords
ENCRYPTED PASSWORDS
How is it possible to decrypt passwords protected by Microsoft technologies?
Key Point: If an application or OS can decrypt it, so can an attacker!
…sometimes administrator access is required.
ENCRYPTED PASSWORDS
How is it possible to recover passwords encrypted by Microsoft technologies?
• Calling native OS and application functions
• Recovering encryption keys From same system as the protected data From external systems like HSMs
• Use the keys and correct algorithm to recover protected data
ENCRYPTED PASSWORDS
Groups.xml• Windows AD Group Policy Preferences
allow setting passwords for local accounts on domain systems
ENCRYPTED PASSWORDS
Groups.xml• For that to work the password has to be
sent to the user’s system• Groups.xml is pulled down from the
SYSVOL share on the DC• SYSVOL and Groups.xml are accessible to
all domain users and computer accounts
ENCRYPTED PASSWORDS
• Updating a user results in groups.xml file creation
ENCRYPTED PASSWORDS
• Passwords in groups.xml are AES256 encrypted and base64 encoded
• To apply the password locally, client has to decrypt it
• To enable this, encryption key is stored on clients
• But MS released the STATIC key in an MSDN article; now anyone can decrypt the password!
http://msdn.microsoft.com/en-us/library/2c15cbf0-f086-4c74-8b70-1f2fa45dd4be.aspx#endNote2
ENCRYPTED PASSWORDS
• Groups.xml password decrypted with a simple PowerShell script
https://github.com/mattifestation/PowerSploit/blob/master/Exfiltration/Get-GPPPassword.ps1
ENCRYPTED PASSWORDS
Groups.xml
Recommendations• Microsoft does not recommend setting passwords
via Group Policy so it’s not a good idea to do that
• Access to groups.xml cannot be prevented for domain users so it should not be used
ENCRYPTED PASSWORDS
LSASecrets
• Used to store all kinds of passwords Service accounts Autologin Applications
ENCRYPTED PASSWORDS
LSASecrets
• Passwords are stored encrypted in the registry
HKLM:\SECURITY\Policy\Secrets• Only viewable by LocalSystem
• But…administrators can become LocalSystem
ENCRYPTED PASSWORDS
LSASecrets
sdf
Administrator Access LocalSystem Access
ENCRYPTED PASSWORDS
LSASecrets
• Additional information is also required from the subkeys of
HKLM:\SECURITY\Policy\
ENCRYPTED PASSWORDS
LSASecrets
• Use native API methods to decrypt the secretsLsaRetrievePrivateDataLsaStorePrivateDataLsaOpenPolicyLsaNtStatusToWinErrorLsaCloseLsaFreeMemory
ENCRYPTED PASSWORDS
LSASecrets – Service Account Example
ENCRYPTED PASSWORDS
WDigest
• Designed for use protocols that require a cleartext password to authenticate: Hypertext Transfer Protocol (HTTP) Simple Authentication Security Layer (SASL) exchanges
http://technet.microsoft.com/en-us/library/cc778868(v=ws.10).aspx
http://www.slideshare.net/gentilkiwi
ENCRYPTED PASSWORDS
WDigest
• Stores passwords for interactive logins (like RDP) encrypted in the lsass.exe process
• Depending on secret size and OS versionRC4, DES, or AES is used
http://technet.microsoft.com/en-us/library/cc778868(v=ws.10).aspx
http://www.slideshare.net/gentilkiwi
ENCRYPTED PASSWORDS
WDigest
• After injecting into the lsass.exe process or importing initialized keys via lsasrv.dll…
• Native functions from lsasrv.dll can be used to decrypt the passwords – namely…
LsaUnprotectMemory
http://www.slideshare.net/gentilkiwi
http://msdn.microsoft.com/en-us/library/windows/desktop/ff714510(v=vs.85).aspx
ENCRYPTED PASSWORDS
WDigest
• Tools like Mimikatz and WCE can be used to recover cleartext passwords
http://www.slideshare.net/gentilkiwi
http://msdn.microsoft.com/en-us/library/windows/desktop/ff714510(v=vs.85).aspx
ENCRYPTED PASSWORDS
WDigest
Recommendations
• Use smartcard or biometrics when possible
• Use network logins instead of interactive logs when possible
• Use unprivileged accounts when possible
• Do not provide admin / system / debug privileges to users
http://www.slideshare.net/gentilkiwi
ENCRYPTED PASSWORDS
DPAPI
• Windows Data Protection API (DPAPI)
• Standard / easy way on Windows to encrypt and decrypt data
• DPAPI used by many applications IE, Chrome, Skype, EFS certificates, WEP / WPA keys, RDP passwords, Credential Manager
• Data protection in memory or on disk
ENCRYPTED PASSWORDS
DPAPI – stored data
• Two protection scopes: CurrentUser or LocalMachine
• Protection scope determines the encryption keys CurrentUser scope uses keys protected by current user’s password
LocalMachine scope uses keys on the system
• Additional entropy added to strengthen protection
ENCRYPTED PASSWORDS
DPAPI - internals
• Largely undocumented by Microsoft – just the API calls are fully documented
• DPAPI has been reversed and offline decryption tools have been released
http://passcape.com/index.php?section=blog&cmd=details&id=20#11http://www.elie.net/publication/reversing-dpapi-and-stealing-windows-secrets-offline#.U3BnB_ldWDs
ENCRYPTED PASSWORDS
MSSQL Links - Background
• Microsoft SQL Server allows users to create links to external data sources, typically to SQL Servers
• Links can be configured to use SQL server credentials
• Cleartext passwords are needed to connect to linked servers – password hashing cannot be used
ENCRYPTED PASSWORDS
MSSQL Links - Background
ENCRYPTED PASSWORDS
MSSQL Links – Password Storage
• Linked server passwords stored in the database – only accessible using DAC
• Passwords stored in pwdhash column even though hashing is not used
• Passwords encrypted but SQL Server must have the key
ENCRYPTED PASSWORDS
MSSQL Links – Password Storage
ENCRYPTED PASSWORDS
MSSQL Links – Service Master Key
• SQL Server has a Service Master Key which is encrypted using DPAPI
• Additional entropy is stored in the registry
• Service Master Key is “the root of the SQL Server encryption hierarchy”, used to encrypt linked server passwords too
ENCRYPTED PASSWORDS
MSSQL Links – Service Master Key
ENCRYPTED PASSWORDS
MSSQL Links – Passwords Decryption
• Decrypt Service Master Key using DPAPI
• Extract encrypted password from database
• Remove metadata from the password
• Decrypt password using Service Master Key (either 3DES or AES depending on version)
ENCRYPTED PASSWORDS
MSSQL Links – Passwords Decrypted
ENCRYPTED PASSWORDS
MSSQL Links
Recommendations
• Best practice is to use Windows authentication only – do not enable SQL server authentication
• Configure linked servers to use current execution context rather than saved credentials
ENCRYPTED PASSWORDS
Credential Manager / Vault
• Credential Manager is intended to be a secure way to store password
• Can be used for Windows credentials, browser credentials, application credentials
• Each user has their own Vault – user can store own passwords
ENCRYPTED PASSWORDS
Credential Manager / Vault
• Cleartext credentials needed to connect to remote systems – thus passwords in Cred Manager are encrypted, not hashed.
• DPAPI used to encrypt passwords
ENCRYPTED PASSWORDS
Credential Manager / Vault
ENCRYPTED PASSWORDS
Credential Manager / Vault• Credential manager password decryption using
Cain
http://www.oxid.it/
ENCRYPTED PASSWORDS
Credential Manager / Vault
Recommendations
• Stored passwords always a security risks
• Consider disabling Credential Manager using group policies
ENCRYPTED PASSWORDS
Wireless
• Wireless connections with pre-shared keys have to store the passwords
• Passwords encrypted using DPAPI
• User or SYSTEM can access the stored passwords
• Multiple tools to extract wireless credentials, including Metasploit
ENCRYPTED PASSWORDS
Wireless
ENCRYPTED PASSWORDS
Wireless
Metasploit module: post/windows/wlan/wlan_profile
ENCRYPTED PASSWORDS
Wireless
Recommendations
• Do not use pre-shared keys
• Configure corporate wireless to use WPA2-Enterprise (integrated authentication)
ENCRYPTED PASSWORDS
Web.config and ApplicationHost.config
• IIS application configuration files
• Web.config = application level
• ApplicationHost.config = server level Application pool credentials Windows credentials used for directory access
… but they can also be decrypted
ENCRYPTED PASSWORDS
Web.config and ApplicationHost.config
• Early saw this
aspnet_regiis.exe -pef "connectionStrings" c:\webapp
ENCRYPTED PASSWORDS
Web.config and ApplicationHost.config
• No surprise that local administrators can do this:
aspnet_regiis.exe -pdf "connectionStrings" c:\webapp
HASHED PASSWORDS
Why should I care if someone is stealing my password hashes if I have complexity enabled?
•#1 Reason:
Password hashes can be replayed and used to authenticate without knowledge of the password
HASHED PASSWORDS
Why should I care if someone is stealing my password hashes if I have complexity enabled?
•#2 Reason:
Password hashes can cracked at lighting speeds using modern hardware and software
HASHED PASSWORDS
On the System
• Local / Domain LM hashes
• Local / Domain NTLM hashes
• Domain MS-CACHEv2
On the Network
• Local / Domain NetLM
• Local / Domain NetNTLM
HASHED PASSWORDS
Can be dumped with a billion different hacker tools!
DO I REALLY NEED PASSWORDS?
Short answer is NO
DO I REALLY NEED PASSWORDS?
• SMB relay
• Pass-the-hash
• Stealing authentication tokens
• Crawling database links
• Process migration
• Generating golden tickets
CONCLUSIONS
• Protecting passwords is really, really hard if an attacker has admin rights to you system
• Don’t store passwords in clear text – Anywhere!
• Only use encryption when the cleartext passwords need used later
• Use HSM to protect keys used to encrypt data
• Use strong salted hashes to protect passwords
• Enforce least privilege everywhere – networks, servers, applications…EVERYWHERE
NETSPI REFERENCES
• NetSPI blog: http://www.netspi.com/blog
• NetSPI github: https://github.com/netspi
• Scott github:https://github.com/nullbind
• NetSPI slideshare: http://slideshare.com/netspi
• Scott slideshare: http://slideshare.com/nullbind
• Scott twitter: @_nullbind