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Forensics of a Windows system

Alfredo Reino

Systems Engineer

Pharma Global Informatics

F. Hoffmann-La Roche

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F. Hoffmann – La RocheA Global Healthcare Leader

• One of the leading research-intensive healthcare groups

• Core businesses are pharmaceuticals and diagnostics

• A world leader in Diagnostics

• The leading supplier of medicines for cancer and transplantation and a market leader in virology

• Employs roughly 65,000 people in 150 countries

• Has R&D agreements and strategic alliances with numerous partners, including majority ownership interests in Genentech and Chugai

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Agenda

• What is forensics?

• Role of forensics in incident handling

• Gathering volatile data

• Filesystem acquisition

• Timeline analysis

• Network information

• Tools

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What is forensics?

Computer forensics is the process of investigating data storage devices and/or data processing equipment typically a home computer, laptop, server, office workstation, or removeable media such as compact discs, to determine if the equipment has been used for illegal, unauthorized, or unusual activities. It can also include monitoring a network for the same purpose. They must do so in a fashion that adheres to the standards of evidence that is admissible in a court of law.

http://en.wikipedia.org/wiki/computer_forensics

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What is forensics?

• Computer forensics includes the following aspects:– identify evidence– preserve evidence– analyze evidence– present results

• This has to be done following appropiate standards, especially if results need to be admitted by court of law

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Incident handling

• General areas of incident handling– planning and preparation– incident detection– containment / response– recovery – analysis

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Forensics scope and environment

external environment

lan / dmz

infrastructure systems

computerized systems

serveros

applications

do you have all the relevant information?

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Gathering data

• Volatile data– registers, cache contents– memory contents– network connections– running processes

• Non-volatile data– content of filesystems and drives– content of removable media

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Volatile data - preparation

• Create cd-rom with trusted toolset– at least include a trusted version of CMD.EXE from the same operating

system– netcat or cryptcat (http://sourceforge.net/projects/cryptcat/)– system tools (ipconfig, netstat, date, time, net, arp ...) for different

windows versions and service pack levels– pstools, listdlls, filemon, regmon, autoruns... (http://sysinternals.com)– hfind, fport, ntlast, ... (http://foundstone.com)– windows resource kit tools– a good sniffer (ethereal, windump, ...)– md5sum / md5deep

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Volatile data - the set up

• Connect forensics workstation to same lan as suspect server

• Configure netcat or cryptcat in forensics workstation to listen on a port and save received data to evidence file

• Mount trusted toolset cd-rom in suspect server

• Open trusted console (cmd.exe)

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Volatile data - what to get

• System date and time

• Running processes

• Network connections

• Open ports

• Applications listening on open sockets

• Logged on users

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Volatile data - tools

• date /t & time /t– get system date and time

• ipconfig /all– get tcp/ip configuration

• netstat -aon– get network connections and listening ports (with associated process pid)

• psinfo -shd– get computer information (hardware, software, hotfixes, versions, etc.)

• pslist -t– get running processes

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Volatile data - tools

• psloggedon– show logged on users and log on times

• psloglist– dump event log

• psservice– dump system service information

• net use– list netbios/smb connections

• listdlls– list all dlls loaded in system

• sigcheck -u -e c:\windows\system32– enumerate all unsigned files (.exe, .dll)

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Volatile data - tools

• streams -s c:\– list files with alternate data streams (ads)

• logonsessions -p– lists logged on sessions and processes running on each session

• strings– searches for ascii/unicode strings in suspicious files (you decide which

are suspicious or not!)

• arp -a– displays arp cache table

• ntlast – record succesful and failed logins in system (including null sessions and

remote logins)

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Volatile data - tools

• autorunsc– show all kinds of autorun items

• hfind c:– finds hidden files

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Volatile data - GUI tools

• rootkit revealer– detects usermode or kernelmode rootkits

• process explorer– useful information about running processes, loaded libraries,

used resources, etc.

• tcpview– displays network connections and associated applications

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Network information

• Useful static data to get– IDS/IPS logs– firewall logs– radius/VPN logs– DHCP logs and leased ip information– application logs from other servers in same network if they

are suspected of being entry point (ftp, www, database, ...)

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Network information

• Traffic to/from live system– use of sniffer recommended– can use ethernet probe (read-only cat5 if possible!) – if server connected to hub, then plug probe into hub– if connected to switch, use a mirror port (in expensive

switches) or use arp-spoofing to redirect traffic to sniffer– best sniffer: ethereal

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Filesystem acquisition

• Physical acquisition– turn off machine (plug power cable)– remove harddisk– connect to forensics workstation using hardware IDE/SCSI

write blocker– perform bitwise copy

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Filesystem acquisition

• Network acquisition - live system– not recommended

• untrusted operating system• filesystem in inconsistent state

– configure forensics workstation• lots of free disk space• netcat listener (nc -l -p 9000 > disk1.dd)• after acquiring compute hash (md5sum disk1.dd > disk.md5)

– acquire live filesystem• run 'dd for windows' from trusted cd-rom toolset• dd if=\\.\PhysicalDrive0 bs=2k | nc -w 3 10.0.0.1 9000

– where 10.0.0.1 is the ip address of forensics workstation

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Filesystem acquisition

• Network acquisition - non-live system– configure forensics workstation

• lots of free disk space• netcat listener (nc -l -p 9000 > disk1.dd)• after acquiring compute hash (md5sum disk1.dd > disk.md5)

– configure suspect system• boot suspect system (losing volatile info!) into linux livecd

distro (gentoo, helix, knoppix, ...)• run dd to image disk over network with netcat

– dd if=/dev/sda | nc 10.0.0.1 9000

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Filesystem analysis

• Many tools for this– EnCase (commercial)– The Sleuth Kit + forensics browser– ftimes

• Basic analysis tool functionality– file topography– compute hashes for files– create timeline analysis (mac data)– identify and recover deleted files– search functions– case management

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Filesystem analysis

• The Sleuth Kit + forensics browser

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Filesystem analysis

• EnCase 5

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Timeline analysis - other sources

• LastWrite information in registry keys– use 'lsreg.pl' to parse registry and extract information

including lastwrite dataKey -> CurrentControlSet\Control\Windows\ShutdownTimeLastWrite : Tue Aug 2 12:06:56 2005

Value : ShutdownTime;REG_BINARY;c4 96 a0 ad 5a 97 c5 01

• INFO2 files– contains information about deleted files by each user (only if

it goes to recycle bin)– use 'rifiuti' to extract information– file normally at C:\Recycler\%SID%\INFO2

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Timeline analysis - other sources

• Prefetch folder– used by windows to store information about how to effectively launch

executables to improve performance– XP prefetches at boot time and application launch, 2003 prefetches only

at boot time (default)– .pf files in %systemroot%/prefetch folder– the .pf contains information about file paths– the mac info of the .pf file gives us information about when an

application has been launched– use 'pref' or 'pref_ver' to parse this info

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Timeline analysis - other sources

• Logs– event logs (application, system, security)

• very useful, many tools to extract– IIS/webserver/FTP logs

• useful to detect webapp exploiting (maybe as point of entry), for example unicode attacks, sql injection, ...

– setupapi.log• information about installation of applications and devices

– schedlgu.txt• information about scheduled tasks

– antivirus logs– ...

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Timeline analysis - other sources

• Recently opened documents- check this registry key (for each user!)

HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\RunMRU

• Temp folders– examine contents for suspicious files

• Web browser cache– 'pasco' tool for internet explorer forensic analysis– cache and cookies folders– browser history

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Analysis of evidence

• Need to find "footprints"• Initial analysis

– check for hidden or unusual files– check for unusual processes and open sockets– check for unusual application requests– check for suspicious accounts– determine patch level of system

• Based on findings, we should develop a strategy for further investigation– full filesystem analysis– recovery of deleted files– password cracking– analysis of pagefile– ...

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Tools

• These are the mentioned tools in this presentation

• Feel free to add more to your toolkit

• Script (vbscript, perl) your toolset!!

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Licensing

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Thanks for your attention.