Chapter 4Chapter 4

Hacking Windows Hacking Windows

Part 2Part 2

Authenticated AttacksAuthenticated Attacks

Privilege Escalation Privilege Escalation

Pilfering Pilfering – Grabbing the Password Hashes Grabbing the Password Hashes – Cracking Passwords Cracking Passwords – LSADump LSADump – Previous Logon Cache Dump Previous Logon Cache Dump

Remote Control and Back Doors Remote Control and Back Doors

Port Redirection Port Redirection

CountermeasuresCountermeasures

Covering TracksCovering Tracks

Privilege Escalation Privilege Escalation

Once a user can log on to a Windows Once a user can log on to a Windows machine as a Guest or Limited User, the machine as a Guest or Limited User, the next goal is to escalate privileges to next goal is to escalate privileges to Administrator or SYSTEMAdministrator or SYSTEM– Getadmin was an early exploit (link Ch 4r)Getadmin was an early exploit (link Ch 4r)– There have been many others, including a There have been many others, including a

buffer overrun MS03-013 (link Ch 4s)buffer overrun MS03-013 (link Ch 4s)

SYSTEM statusSYSTEM status

The SYSTEM account is more powerful The SYSTEM account is more powerful than the Administrator accountthan the Administrator account

The Administrator can schedule tasks to The Administrator can schedule tasks to be performed as SYSTEMbe performed as SYSTEM– It's more complicated in Vista, but still It's more complicated in Vista, but still

possiblepossible

Making a SYSTEM Task in VistaMaking a SYSTEM Task in Vista

Start, Task SchedulerStart, Task Scheduler

Action, Create TaskAction, Create Task

Change User or Group, select SYSTEMChange User or Group, select SYSTEM

Fill in wizard, notepad.exeFill in wizard, notepad.exe

You can see it in Task Manager, but it's You can see it in Task Manager, but it's not interactive (see link Ch 4t)not interactive (see link Ch 4t)

Preventing Privilege Escalation Preventing Privilege Escalation

Keep machines patchedKeep machines patched

Restrict interactive logon to trusted Restrict interactive logon to trusted accountsaccounts– Start, secpol.mscStart, secpol.msc– Deny log on locallyDeny log on locally

Pilfering Pilfering

Once Administrator-equivalent status has Once Administrator-equivalent status has been obtained on one machinebeen obtained on one machine

Attackers try to gather important Attackers try to gather important information – information – pilferingpilfering

Common TargetsCommon Targets– Password hashesPassword hashes– LSA SecretsLSA Secrets– Previous Logon CachePrevious Logon Cache

Grabbing the Password Hashes Grabbing the Password Hashes

Stored in in the Windows Security Stored in in the Windows Security Accounts Manager (SAM) under NT4 and Accounts Manager (SAM) under NT4 and earlier, andearlier, andIn the Active Directory on Windows 2000 In the Active Directory on Windows 2000 and greater domain controllers (DCs) and greater domain controllers (DCs) The SAM contains the usernames and The SAM contains the usernames and hashed passwords of all users hashed passwords of all users – The counterpart of the /etc/passwd file from The counterpart of the /etc/passwd file from

the UNIX world the UNIX world

Obtaining the Hashes Obtaining the Hashes

NT4 and earlier stores password hashes NT4 and earlier stores password hashes in %systemroot%\system32\config\SAMin %systemroot%\system32\config\SAM– It's locked as long as the OS is runningIt's locked as long as the OS is running– It's also in the Registry key It's also in the Registry key

HKEY_LOCAL_MACHINE\ SAM HKEY_LOCAL_MACHINE\ SAM

On Windows 2000 and greater domain On Windows 2000 and greater domain controllers, password hashes are kept in controllers, password hashes are kept in the Active Directorythe Active Directory– %windir%\WindowsDS\ntds.dit%windir%\WindowsDS\ntds.dit

How to Get the HashesHow to Get the Hashes

Boot the target system to an alternate OS and Boot the target system to an alternate OS and copy the files to removable mediacopy the files to removable media

Copy the backup of the SAM file created by the Copy the backup of the SAM file created by the Repair Disk UtilityRepair Disk Utility– But this file is protected by SYSKEY encryption, which But this file is protected by SYSKEY encryption, which

makes it harder to crack (perhaps impossible)makes it harder to crack (perhaps impossible)– Note: SYSKEY also protects the original SAMNote: SYSKEY also protects the original SAM

But if you have Administrator access, SYSKEY can be But if you have Administrator access, SYSKEY can be cracked, unless you have moved the key off the computercracked, unless you have moved the key off the computer

– Links Ch 4u, 4v, 4wLinks Ch 4u, 4v, 4w

How to Get the HashesHow to Get the Hashes

Sniff Windows authentication exchangesSniff Windows authentication exchanges

Extract the password hashes from a Extract the password hashes from a running system with pwdump2running system with pwdump2– Can bypass SYSKEY protectionCan bypass SYSKEY protection– Injects a DLL into a highly privileged process Injects a DLL into a highly privileged process

in a running systemin a running system– Link Ch 4xLink Ch 4x

We'll use Ophcrack to do itWe'll use Ophcrack to do it

pwdump2 Countermeasures pwdump2 Countermeasures

There is no defense against pwdump2, 3, There is no defense against pwdump2, 3, 4, …4, …

But the attacker needs local Administrative But the attacker needs local Administrative rights to use themrights to use them

Cracking Passwords Cracking Passwords

The hash is supposed to be really difficult The hash is supposed to be really difficult to reverseto reverse– NTLM hashes are really hard to breakNTLM hashes are really hard to break– But Windows still uses LM Hashes for But Windows still uses LM Hashes for

backwards compatibilitybackwards compatibility– They are turned off by default in VistaThey are turned off by default in Vista

Brute Force v. DictionaryBrute Force v. Dictionary

There are two techniques for cracking There are two techniques for cracking passwordspasswords– Brute ForceBrute Force

Tries all possible combinations of charactersTries all possible combinations of characters

– DictionaryDictionaryTries all the words in a word list, such as able, Tries all the words in a word list, such as able, baker, cow…baker, cow…

May try variations such as ABLE, Able, @bl3, etc.May try variations such as ABLE, Able, @bl3, etc.

Password-Cracking Password-Cracking Countermeasures Countermeasures

Strong passwords – not dictionary words, Strong passwords – not dictionary words, long, complexlong, complex

Add non-printable ASCII characters like Add non-printable ASCII characters like (NUM LOCK) ALT255 or (NUM LOCK) (NUM LOCK) ALT255 or (NUM LOCK) ALT-129 ALT-129

LSADump LSADump

Local Security Authority (LSA) Secrets Local Security Authority (LSA) Secrets – Contains unencrypted logon credentials for Contains unencrypted logon credentials for

external systemsexternal systems– Available under the Registry subkey of Available under the Registry subkey of

HKEY_LOCAL_MACHINE\SECURITY\Policy\HKEY_LOCAL_MACHINE\SECURITY\Policy\SecretsSecrets

– Encrypted when the machine is off, but Encrypted when the machine is off, but decrypted and retained in memory after login decrypted and retained in memory after login

Contents of LSA SecretsContents of LSA Secrets

Service account passwords in Service account passwords in plaintext.plaintext. – Accounts in external domainsAccounts in external domains

Cached password hashes of the last ten Cached password hashes of the last ten users to log on to a machineusers to log on to a machineFTP and web-user plaintext passwords FTP and web-user plaintext passwords Remote Access Services (RAS) dial-up Remote Access Services (RAS) dial-up account names and passwordsaccount names and passwordsComputer account passwords for domain Computer account passwords for domain accessaccess

Scary DemoScary Demo

Boot Win XP, log in with your usual Admin Boot Win XP, log in with your usual Admin acctacctChange your passwordChange your passwordUse Cain to dump the LSA Secrets – your Use Cain to dump the LSA Secrets – your password is just right there in the password is just right there in the DefaultPasswordDefaultPasswordLog in as a different Administrator userLog in as a different Administrator userThe LSA Secrets show your other The LSA Secrets show your other account's password!account's password!– Link Ch 4z01Link Ch 4z01

Win XP Password in LSA SecretsWin XP Password in LSA Secrets

LSA Secrets Countermeasures LSA Secrets Countermeasures

There's not much you can do—Microsoft There's not much you can do—Microsoft offers a patch but it doesn't help muchoffers a patch but it doesn't help much– Microsoft KB Article ID Q184017 (link Ch Microsoft KB Article ID Q184017 (link Ch

4z02)4z02)

Vista seems far less vulnerableVista seems far less vulnerable

Local Admin rights can lead to Local Admin rights can lead to compromise of other accounts that compromise of other accounts that machine has logged in tomachine has logged in to

Previous Logon Cache Dump Previous Logon Cache Dump

If a domain member cannot reach the domain If a domain member cannot reach the domain controller, it performs an offline logon with controller, it performs an offline logon with cached credentialscached credentials

The last ten domain logons are stored in the The last ten domain logons are stored in the cache, in an encrypted and hashes formcache, in an encrypted and hashes form

The tool CacheDump can reverse the encryption The tool CacheDump can reverse the encryption and get the hashed passwordsand get the hashed passwords– Download it at link Ch 4z03Download it at link Ch 4z03– More info at links Ch 4z04, 4z05More info at links Ch 4z04, 4z05

CacheDump Results CacheDump Results

John the Ripper can crack these hashes John the Ripper can crack these hashes with brute-force and dictionary attackswith brute-force and dictionary attacks– Another cracking tool is cachebf (link Ch z06)Another cracking tool is cachebf (link Ch z06)

Previous Logon Cache Dump Previous Logon Cache Dump Countermeasures Countermeasures

You need Administrator or SYSTEM You need Administrator or SYSTEM privileges to get the hashesprivileges to get the hashes

You can also adjust the Registry to You can also adjust the Registry to eliminate the cached credentialseliminate the cached credentials– But then users won't be able to log in when a But then users won't be able to log in when a

when a domain controller is not accessible when a domain controller is not accessible

Remote Control and Back Doors Remote Control and Back Doors

Command-line Remote Control Tools Command-line Remote Control Tools

Netcat for WindowsNetcat for Windows– Download it at link Ch 3dDownload it at link Ch 3d– Use this syntax to listen on port 8080, and execute Use this syntax to listen on port 8080, and execute

cmdcmd

– Add –d for stealth mode (no interactive console)Add –d for stealth mode (no interactive console)– Obviously this is very dangerous—remote control with Obviously this is very dangerous—remote control with

no logonno logon

Connecting to the nc ListenerConnecting to the nc Listener

On another machine connect with On another machine connect with – TELNET TELNET IP IP 80808080

– You get a shell on the other machineYou get a shell on the other machine

– Works on VistaWorks on Vista

PsExecPsExec

From SysInternals (now part of Microsoft)From SysInternals (now part of Microsoft)

Allows remote code execution (with a Allows remote code execution (with a username and password)username and password)– Link Ch 4z07Link Ch 4z07

Graphical Remote Control Graphical Remote Control

The Windows Built-in Terminal Services The Windows Built-in Terminal Services (aka Remote Desktop) listens on port (aka Remote Desktop) listens on port 33893389– It's not on by defaultIt's not on by default

VNC is free and very commonly used for VNC is free and very commonly used for graphic remote controlgraphic remote control– Can easily be installed remotelyCan easily be installed remotely– Link Ch 4z08Link Ch 4z08

VNC as used in MetaSploitVNC as used in MetaSploit

Remote Access TrojansRemote Access Trojans

There are a lot of them, includingThere are a lot of them, including– Poison Ivy (link Ch 4z09)Poison Ivy (link Ch 4z09)– GoToMyPC (link Ch 4z10)GoToMyPC (link Ch 4z10)– LogMeIn Hamachi (link Ch 4z11)LogMeIn Hamachi (link Ch 4z11)

Remote Control Countermeasures Remote Control Countermeasures

Prevent attackers from gaining Prevent attackers from gaining administrator rights on your machineadministrator rights on your machine

You can find and stop running remote You can find and stop running remote control clients with malware scans, looking control clients with malware scans, looking for unusual network connections or trafficfor unusual network connections or traffic– It can be very hard if the connections are It can be very hard if the connections are

hidden by a rootkithidden by a rootkit

Port Redirection Port Redirection

Fpipe is a port redirection tool from Fpipe is a port redirection tool from FoundstoneFoundstone– Link Ch 4z12Link Ch 4z12

General Countermeasures to General Countermeasures to Authenticated CompromiseAuthenticated Compromise

Once a system has been compromised Once a system has been compromised with administrator privileges, you should with administrator privileges, you should just reinstall it completelyjust reinstall it completely– You can never be sure you really found and You can never be sure you really found and

removed all the backdoorsremoved all the backdoors

But if you want to clean it, here are But if you want to clean it, here are techniques:techniques:

Suspicious FilesSuspicious Files

Known dangerous filenames like nc.exeKnown dangerous filenames like nc.exe

Run antivirus softwareRun antivirus software

Use Tripwire or other tools that identify Use Tripwire or other tools that identify changes to system fileschanges to system files– Link Ch 4z13Link Ch 4z13

Suspicious Registry EntriesSuspicious Registry Entries

Look for registry keys that start known Look for registry keys that start known backdoors like"backdoors like"– HKEY_USERS\.DEFAULT\Software\HKEY_USERS\.DEFAULT\Software\

ORL\WINVNC3 ORL\WINVNC3 – HKEY_LOCAL_MACHINE\SOFTWARE\HKEY_LOCAL_MACHINE\SOFTWARE\

Net Solutions\NetBus Server Net Solutions\NetBus Server

A Back-Door Favorite: Autostart A Back-Door Favorite: Autostart Extensibility Points (ASEPs) Extensibility Points (ASEPs)

Ways to Make a Program Run at Ways to Make a Program Run at Startup in VistaStartup in Vista

Registry keysRegistry keys– Run or RunOnce or Policies\Explorer\RunRun or RunOnce or Policies\Explorer\Run– Load valueLoad value– RunServices or RunServicesOnceRunServices or RunServicesOnce– Winlogon or BootExecuteWinlogon or BootExecute

Scheduled TasksScheduled Tasks

Win.iniWin.ini

Group PolicyGroup Policy

Shell service objectsShell service objects

Logon scriptsLogon scripts

Suspicious ProcessesSuspicious Processes

Process Process ExplorerExplorerLink Ch 4z14Link Ch 4z14

Suspicious PortsSuspicious Ports

Use Use netstat -aonnetstat -aon to view network to view network connectionsconnections

FPORT Process MapperFPORT Process Mapper

Doesn't work on VistaDoesn't work on Vista

Software ExplorerSoftware Explorer

Part of Windows Defender in VistaPart of Windows Defender in Vista

Covering TracksCovering Tracks

Once intruders have Administrator or Once intruders have Administrator or SYSTEM-equivalent privileges, they will:SYSTEM-equivalent privileges, they will:– Hide evidence of intrusionHide evidence of intrusion– Install backdoorsInstall backdoors– Stash a toolkit to use for regaining control in Stash a toolkit to use for regaining control in

the future and to use against other systemsthe future and to use against other systems

Disabling Auditing Disabling Auditing

The auditpol /disable command will stop The auditpol /disable command will stop auditingauditing

Auditpol /enable will turn it back on againAuditpol /enable will turn it back on again– Auditpol is included in VistaAuditpol is included in Vista– Part of the Resource Kit for earlier versions Part of the Resource Kit for earlier versions

(XP, NT, 2000 Server)(XP, NT, 2000 Server)

Clearing the Event Log Clearing the Event Log

ELsave – command-line log clearing toolELsave – command-line log clearing tool– Written for Windows NTWritten for Windows NT– Link Ch 4z15Link Ch 4z15

Hiding FilesHiding Files

Attrib +h filenameAttrib +h filename– Sets the Hidden bit, which hides files Sets the Hidden bit, which hides files

somewhatsomewhat

Alternate Data StreamsAlternate Data Streams– Hide a file within a fileHide a file within a file– A NT feature designed for compatibility with A NT feature designed for compatibility with

MacintoshMacintosh

Demonstration of ADSDemonstration of ADS

ADS With Binary FilesADS With Binary Files

You need the cp command (supposedly in You need the cp command (supposedly in the Resource Kit, although I can't find it the Resource Kit, although I can't find it available free online)available free online)

To detect alternate data streams, use To detect alternate data streams, use LADS (link Ch 4z16)LADS (link Ch 4z16)

RootkitsRootkits

Rootkits are the best way to hide files, Rootkits are the best way to hide files, accounts, backdoors, network accounts, backdoors, network connections, etc. on a machineconnections, etc. on a machine

More on rootkits in a later chapterMore on rootkits in a later chapter

Windows Security Features Windows Security Features

Keep Up with Patches Keep Up with Patches Group PolicyGroup Policy– Allows customized security settings in Allows customized security settings in

domainsdomains

IPSec filters can be used to block IPSec filters can be used to block unwanted network trafficunwanted network traffic– Windows Firewall is easier to useWindows Firewall is easier to use– Windows Firewall With Advanced Security is Windows Firewall With Advanced Security is

greatly enhanced in Vistagreatly enhanced in Vista

Least PrivilegeLeast Privilege

Most Windows users use an Most Windows users use an Administrative accout all the timeAdministrative accout all the time– Very poor for security, but convenientVery poor for security, but convenient– For XP, 2003, and earlier: log on as a limited For XP, 2003, and earlier: log on as a limited

user, use runas to elevate privileges as user, use runas to elevate privileges as neededneeded

– For Vista and Server 2008, this process is For Vista and Server 2008, this process is automated by User Account Controlautomated by User Account Control

Encrypting File System (EFS) Encrypting File System (EFS)

Can encrypt files or foldersCan encrypt files or folders

This protects critical files from intrudersThis protects critical files from intruders

In Vista, BitLocker Drive Encryption is In Vista, BitLocker Drive Encryption is much strongermuch stronger– Only on Enterprise and Ultimate EditionOnly on Enterprise and Ultimate Edition– BUT: there is a way to crack BitLocker by BUT: there is a way to crack BitLocker by

taking the key out of RAM (link Ch 4z17)taking the key out of RAM (link Ch 4z17)

Video: Hacking BitLockerVideo: Hacking BitLocker

Last modified 2-22-08Last modified 2-22-08