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Module XIII – Windows Forensics II

EC-CouncilCopyright © by EC-Council

All Rights Reserved. Reproduction is Strictly Prohibited

News: Vista Encryption ‘No Threat’ to Computer Forensics

Source: http://www.theregister.co.uk/2007/02/02/computer_forensics_vista/



Module Objective

• Collecting Volatile and Non-volatile Information• Windows Memory Analysis• Window Registry Analysis• Window File Analysis• Text-Based Logs• Other Audit Events• Forensic Analysis of Event Logs• Tool Analysis• Windows Password Issues

This module will familiarize you with:



Window Password Issues

Window File Analysis

Window Registry Analysis

Other Audit EventsForensic Analysis of

Event Logs

Metadata Investigation Text Based Logs

MD5 CalculationCache, Cookie and History Analysis

Window Memory Analysis

Collecting Non-Volatile Information

Collecting Volatile Information

Forensics Tools

Module Flow



Understanding Events

Event logs record a variety of day-to-day events that occur on the Window’s systems

Some events are recorded by default and some audit configuration are maintained in the PolAdEvt Registry key

The Registry key which maintains the Event log configuration:

• HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Eventlog\<Event Log>



Understanding Events (cont’d)

Event logon types are shown below:

Logon Type Title Description

2 InteractiveThis logon type indicates that the user is logged in at the console

3Network

A user/computer logged into this computer from the network, such as via net use, accessing a network share, or a successful net view directed at a network share

4 BatchReserved for applications that run as batches

5 Service Service logon





6 Proxy Not supported

7 Unlock The user unlocked the workstation

8 NetworkClearTextA user logged onto a network, and the user’s credentials were passed in an unencrypted form

9 NewCredentialsA process or thread cloned its current token but specified new credentials for outbound connections

10RemoteInteractive Logon using Terminal Services or a

Remote Desktop connection





11 CachedInteractive

A user logged onto the computer with credentials that were stored locally on the computer

12 CachedRemote InteractiveSame as RemoteInteractive, used internally for auditing purposes

13CachedUnlock The logon attempt is to

unlock a workstation



Event Record Structure

The basic header for an event record weighs 56 bytes

Details of the content of the first 56 bytes of an event record are as shown below:

Offset Size Description

04 bytes Length of the event record, or size of the record in

bytes

44 bytes

Reserved; magic number

84 bytes

Record number



Event Record Structure (cont’d)


124 bytes

Time generated; measured in Unix time, or the number of seconds elapsed since 00:00:00 1 Jan 1970, in Universal Coordinated Time (UTC)

164 bytes

Time written; measured in Unix time, or the number of seconds elapsed since 00:00:00 1 Jan 1970, in Universal Coordinated Time (UTC)

204 bytes

Event ID, which is specific to the event source and uniquely identifies the event; the event ID is used along with the source’s name to locate the appropriate description string within the message file for the event source





24 2 bytesEvent type (0x01 = Error; 0x10 = Failure; 0x08 = Success; 0x04 = Information; 0x02 = Warning)

26 2 bytes Number of strings

282 bytes

Event category

302 bytes

Reserved flags

32 4 bytes Closing record number

36 4 bytesString offset; offset to the description strings within this event record

40 4 bytesLength of the user’s SID; size of the user’s SID in bytes (if 0, no user SID is provided)





44 4 bytesOffset to the user’s SID within this event record

48 4 bytesData length; length of the binary data associated with this event record

52 4 bytes Offset to the data



Vista Event Logs

Vista uses an XML format for storing events and it supports central collection of the event records

Use wevtutil command to retrieve information about the Windows Event Log

Command to display a list of available Event Logs on the system:

• C:\>wevtutil el

Command to list configuration information about a specific Event Log:

• C:\>wevtutil gl log name

Information displayed by this command is also available in the following key on a Vista system:

• HKEY_LOCAL_MACHINE\System\ControlSet00x\Services\EventLog\log name



Vista Event Logs: Screenshots

Output of wevtutil el

Output of wevtutil gl system



IIS Logs

Use the web server generated logs for the exploitation of attacks on IIS web server

The IIS web server logs are maintained in the %WinDir%\System32\LogFiles directory

The log files are ASCII text format which implies that they are easily opened and searchable

Parse each entry of the log for relevant information using the column headers as a key



Parsing IIS Logs

Manage and configure IIS through the IIS Management Console only on a system that has IIS installed and running

Access the console by choosing:

•Start → Run→ type either iis.msc or inetmgr

• Start → Control Panel → Administrative Tools → Internet Services Manager

Search the logs stored in the format exyymmdd.log and are created daily by default,where:

•yymmdd stands for year, month, and day

•Ex refers to the extended format

Each field name of the log is prefixed with letters meaning as follows:

• c = client actions• s = server actions• cs = client to server actions• sc = server to client actions



Parsing IIS Logs (cont’d)

IIS log fields used in W3C extended log file format are as shown below:

Field Name Description Logged by Default

date Date on which the activity occurred Yes

timeTime at which the activity occurred, expressed in UTC (GMT)

Yes

c-ip IP address of the client making the request Yes

cs-username Username of the authenticated user who accessed the server. Anonymous users are annotated by a hyphen

Yes





s-sitenameInternet service name and instance number that was serving the request

No

s-computernameName of the server generating the log entry

No

s-ipIP address of the server on which the log file was generated

Yes

s-port Server port number that is used for the connection

Yes

cs-method Requested action requested by the client, most often GET method

Yes

cs-uri-stem Target of the client’s action (default.htm, index.htm, etc.)

Yes





cs-uri-query Query, if any, requested by the client (Used when sending data to a server-side script)

Yes

sc-status HTTP status code sent by the server to the client

Yes

sc-win32-status Windows status code returned by the server No

sc-bytes Number of bytes the server sent to the client No

cs-bytes Number of bytes the server received from the client

No

time-taken Length of the time the requested action took, expressed in milliseconds

No





cs-version Protocol version (HTTP or FTP) the client used

No

cs-host Host’s header name, if any No

cs(User-Agent) Browser type used by the client Yes

cs(Cookie) Content of cookie (sent or received), if any No

cs(Referrer)Site last visited by the user. This site provided a link to this current server

No

sc-substatus Substatus error code Yes



Parsing FTP Logs

FTP stands for File Transfer Protocol and an FTP server sends and receives files using FTP

FTP logs do not record the following fields as compared to IIS logs:

• cs-uri-query• cs-host• cs(User-Agent) • cs(Cookie) • cs(Referrer) • sc-substatus

FTP logs are stored in:

•%WinDir%\System32\LogFiles\MSFTPSVC1\exyymmdd.log



Parsing FTP Logs (cont’d)

FTP sc-status Codes are as shown in the table:

Error Code Description

1xx Positive Preliminary Replies

120 Service ready in nnn minutes

125 Data connection already open-transfer starting

150 File status okay-about to open data connection

2xx Positive Completion Replies

202 Command not implemented-superfluous at this site

211 System status or system help reply

212 Directory status

213 File status



Parsing FTP Logs (cont’d)

Error Code Description

214 Help message

215NAME system type, where NAME is an official system name from the list in the Assigned Numbers document

220 Service ready for the new user

221 Service closing control connection. Logged out if appropriate

225 Data connection open-no transfer in progress

226Closing data connection. Requested file action successful (example, file transfer and so on)

227 Entering passive mode

230 User logged in-proceed

250 Requested file action okay-completed



Parsing DHCP Server Logs

In DHCP, an IP address is dynamically assigned upon request by a host’s machine

The server provides the DHCP-assigned IP address for a period called a lease

DHCP service activity logs are stored in the following location by default:

• C:\%SystemRoot%\System32\DHCP

Logs are stored on a daily basis in the following format:

• DhcpSrvLog-XXX.log



Parsing DHCP Server Logs (cont’d)

DHCP Log Format is as shown in the table below:

Field Description

ID DHCP server event ID code

Date Date on which this record entry was logged by the DHCP service

TimeTime at which this record entry was logged by the DHCP service (stored in local system time zone)

Description Description of this particular DHCP server event

IP Address IP address leased to client

Host Name Host name of the DHCP client to which the IP address is leased

MAC Address Media access control address (MAC) used by the network adapter (NIC) of the client to which the IP address is leased



Parsing Windows Firewall Logs

The firewall logs are present in the %SystemRoot%\pfirewall

It stores data in the objects.data file

It is located in:

• %SystemRoot%\System32\wbem\Repository\FS\

The log file contains header at the top that describes the software and version, the time format, and the fields



Using the Microsoft Log Parser

Use Log Parser tool to extract log files, XML files, and CSV files

The command used for the Log Parser is:

•LogParser.exe -o:DATAGRID “select * from system”

• The first is the input type, or -i:• The second is the output type, or -o:• The third is the query

Every Log Parser command query has three parts:



Log Parser: Screenshot

Log Parser output (command prompt)



Log Parser: Screenshot

Log Parser output (GUI)







Event Logs


MD5 CalculationCache, Cookie, and History Analysis




Forensics Tools



Evaluating Account Management Events

Account management events record the changes made to accounts and group membership

• Creation• Deletion• Disabling of accounts• Modifying which accounts belong to which groups• Account lockouts• Account reactivations

This includes:

Activate auditing for the account management events on a Windows system, to detect activities, attackers perform after gaining access to a system



Evaluating Account Management Events (cont’d)

• Summary of the type of action• The account that performed the action is listed in the Caller User

Name field• The account added or removed is shown in the Member ID field• The group affected is listed as the target account name

The description of an event consists of:



Evaluating Account Management Events (cont’d)

Event ID Action Indicated

632 Member added to global security group

633 Member removed from global security group

636 Member added to local security group

637 Member removed from local security group

650 Member added to local distribution group

651 Member removed from local distribution group

655 Member added to global distribution group

656 Member removed from global distribution group

660 Member added to universal security group

661 Member removed from universal security group

665 Member added to universal distribution group

666 Member removed from universal distribution group



Examining Audit Policy Change Events

Modifications to the audit policy are recorded as entries of Event ID 612

Locate the audit policies at:

• Computer Configuration\Windows Settings\Security Settings\Local Policies\Audit Policy

The ‘+’ symbols indicate which events are audited, whereas the ‘–’ symbols show which audit categories are not audited



Examining System Log Entries

System log contains analysis relevant to the network investigation

• Operating system• Hardware configuration• Device driver installation• Starting and stopping of services

System log contains changes made to the:



Examining Application Log Entries

The Application event log contains messages from the operating system and various programs

Use a program logevent.exe to send the custom messages to the Application event log

Command to Navigate the Application Log Entries:

• Start → Setting→ Control Panel →Administrative Tools→ Event Viewer →Application







Event Logs


MD5 CalculationCache, Cookie and History Analysis




Forensics Tools



Using EnCase to Examine Windows Event Log Files

EnCase can be used to parse Window’s event log files using EnScript

• It helps to keep the processed information within the forensic environment

• It does not rely on the Windows API to process the event logs• It can process event logs that are reported as “corrupt”

Reasons to use EnCase are:



EnCase: Screenshot



Windows Event Log Files Internals

The Windows event logs files are databases with the records related to the system, security, and applications

The database related to system are stored in a file named SysEvent.evt

The database related to security are stored in a file named SecEvent.evt

The database related to Applications are stored in the file named AppEvent.evt

Windows event logs are stored in:

• %SystemRoot%\system32\config\



Windows Event Log Files Internals (cont’d)

Windows event log file field names are as shown in the table:

Field Name Data Pulled From

EventLog Name of the file or the other source being queried

RecordNumber Event file entry – field 2

TimeGenerated Event file entry – field 3, converted to local system time

TimeWritten Event file entry – field 4, converted to local system time

EventID Event file entry – field 5

EventType Event file entry – field 8

EventTypeName Generated by looking up the associated Event Type number

EventCategory Event file entry – field 10



Windows Event Log Files Internals (cont’d)

Field Name Data Pulled From

EventCategoryName Generated by looking up the associated Event Category number

SourceName Event file entry – field 12

StringsEvent file entry – field 17, but replaces the separator 0x0000with the pipe symbol

ComputerName Event file entry – field 13

SID Event file entry – fields 14–16

MessageGenerated from the data in the Strings section and informationcontained within DLLs

Data Event file entry – field 18







Event Logs






Forensics Tools



Understanding Windows Password Storage

Windows systems store the user’s account and password data in:

• Security Account Manager (SAM) file or• Active Directory

SAM files are located in the %SystemRoot%\System32\Config folder

A password is run through a specific algorithm and converted into a numeric value (Hash)

Windows operating systems use two different hash functions and store two different hash values:

• NT LanMan (NTLM) hash• LanMan (LM) hash



Understanding Windows Password Storage (cont’d)



Cracking Windows Passwords Stored on Running Systems

Password cracking refers to the process of taking a password hash and attempting to determine what the associated password will be

• Guessing a possible password• Generating a password hash of the guess using the same hashing

algorithm used by the target system• Comparing the hash of the guess to the hash of the target account• If the match is found, stop the process otherwise start over

The process includes:



Cracking Windows Passwords Stored on Running Systems (cont’d)



Exploring Windows Authentication Mechanisms

Windows systems use the below mentioned authentication mechanisms to access the remote computers:

• Relies on hash to determine whether a remote user has provided a valid username/password combination

LanMan authentication:

• Is calculated across the entire, case-sensitive password, resulting in a 16-byte hash

NTLM authentication:

• Verification of the user’s identity takes place between the Domain Controller and the client

Kerberos:



Sniffing and Cracking Windows Authentication Exchanges

If an attacker is able to monitor communication between the victim’s system and the remote system, he/she can sniff the authentication and use it to crack the user’s password

Windows systems use Server Message Block (SMB) protocol to share files across the network



Cracking Offline Passwords

Use tools to extract the password data from the SAM files and feed it to the password cracker

Files with the encrypted attribute selected are encrypted before being stored

These techniques are used for defeating Windows Encrypting File System (EFS)







Event Logs






Forensics Tools



Windows Forensics Tool: Helix

Helix is a customized distribution of the Knoppix Live Linux CD

You can still boot into a customized Linux environment that includes the customized Linux kernels, excellent hardware detection, and many applications dedicated to Incident Response and Forensics

Helix has a special Windows autorun side for Incident Response and Forensics

Helix focuses on Incident Response and Forensics tools



Windows Forensics Tool: Helix (cont’d)

Helix operates in two different modes –Windows and Linux

In the Windows Mode, it runs as a standard windows application used to collect information from “live” (still turned on and logged in) Windows system



Tools Present in Helix CD for Windows Forensics

Windows Forensics Toolchest (WFT)

Incident Response Collection Report (IRCR2)

First Responder’s Evidence Disk (FRED)

First Responder Utility (FRU)

Security Reports (SecReport)

Md5 Generator

Command Shell

File Recovery – recover deleted files

Rootkit Revealer

VNC Server

Putty SSH

Screen Capture

Messenger Password

Mail Password Viewer

Protected Storage Viewer

Network Password Viewer

Registry Viewer

Asterisk Logger

IE History Viewer

IE Cookie Viewer

Mozilla Cookie Viewer



Screenshot 1



Screenshot 2



Screenshot 3



Screenshot 4



Screenshot 5



Helix Tool: SecReport

• Network Configuration• Audit Policy• Event Log Configuration• Services• Applications• Hotfixes• Ports Open• Page File Settings• Hardware• Processors• Fixed Disks

The report generated by SecReport shows the following information:

It is a small suite of two command-line tools for collecting security-related information from Windows-based system (SecReport) and comparing any two reports either from any two systems or from the same system after some time (Delta)



Helix Tool: Windows Forensic Toolchest (WFT)

The Windows Forensic Toolchest (WFT) was written to provide an automated incident response on a Windows system and collect security-relevant information from the system

It is essentially a forensically enhanced batch processing shell capable of running other security tools and producing HTML based reports

WFT should be run from a CD to ensure the forensic integrity of the evidence it collects



Screenshot 1



Screenshot 2



Screenshot 3

It logs every action and takes as part of running commands



Screenshot 4

WFT saves a copy of every tool's raw output in addition to the HTML reports it generates



A program that displays all the unsigned drivers and related files in the computer

A signed file indicates the authenticity and quality associated to a file from its manufacturer

Any unsigned files can indicate presence of infected driver files placed by attackers

Most of the driver files are signed by the operating system manufacturer such as Microsoft

Helps in finding the unsigned files present in the system

Built-in Tool: Sigverif



Word Extractor

Forensic tool that interprets human words from machine language

Helps in many ways such as finding a cheat in a game, finding hidden text, or passwords in a file (exe, bin, dll), etc.



Registry Viewer Tool: RegScanner

RegScanner is a small utility that allows you to scan the Registry, find the desired Registry values that match the specified search criteria, and display them in one list

• It displays the entire search result at once, so you do not have to press F3 in order to find the next value

• In addition to the standard string search, RegScanner can also find Registry values by data length, value type (REG_SZ, REG_DWORD etc.), and by modified date of the key

• It can find a unicode string located inside a binary value• It allows you to make a case sensitive search • While scanning the Registry, it displays the current scanned Registry key

Features:



Screenshot 1



Screenshot 2



Tool: Pmdump

• A tool that dumps the memory contents of processor to a file without stopping the process

• Stands for Post Mortem Dump• The dump information is saved on some secondary storage medium

such as magnetic tape or disk

PMDump



Tool: System Scanner

System scanner has the ability to fetch more specific information about the processes such as the IDs of all the threads, handles to DLLs, ability to suspend specific threads of a specific process and, finally, an ability to view the process’ virtual memory

User can either dump virtual memory or draw a memory map



Screenshot



Integrated Windows Forensics Software: X-Ways Forensics

• Views and dumps physical RAM and the virtual memory of the running processes

• Clones and images disk, even under DOS with X-Ways Replica • Examines the complete directory structure inside raw image files, even

spanned over several segments • Native support for FAT, NTFS, Ext2/3, CDFS, and UDF • Various data recovery techniques and file carving (hundreds of file

signatures can be imported from FileSig) • Gathering slack space, free space, inter-partition space, and generic text

from drives and images

Features:

X-Ways Forensics is an advanced work environment for computer forensic examiners



Screenshot



Tool - Traces Viewer

Traces Viewer is a tool that allows you to view all images, flash movies, pages, and other media files cached by Internet Explorer browser

It can remove all the web-traces made by Internet Explorer on your computer



Traces Viewer: Images



Traces Viewer: Pages



Traces Viewer: Other



Traces Viewer: Cookies



CD-ROM Bootable Windows XP

The methods to create Bootable CD-ROM for Windows XP:

• Bart PE (Bart Preinstalled Environment)• Provides a complete Win32 environment with network support• Rescues files to a network share, virus scan etc

• Ultimate Boot CD• Provides shared Internet access• Can modify NTFS volumes • Recovers deleted files• Creates new NTFS volumes, scanning viruses etc.



Bart PE Screenshot



Ultimate Boot CD-ROM



List of Tools in UB CD-ROM



List of Tools in UB CD-ROM (cont’d)












Summary

Live system activity notification is important for responders and investors

In live response, the data is collected which is going to change in a short span of time

Several Registry values and settings could impact the forensic analysis

Analyzing the contents of RAM will help the investigator to find what has been hidden

pmdump.exe tool allows dumping the contents of the process memory without stopping the process

Registry Analysis provides more information to the investigator during live response

The logs generated by the web server are used for the exploitation of attacks on IIS web server

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Technology

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bytes event category

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event source

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