lptv4 module 36 file integrity checking

/ECSA/LPT

EC Council M d l XXXVIEC-Council Module XXXVI

File Integrity Checking

Penetration Testing Roadmap

Start HereInformation Vulnerability External

Gathering Analysis Penetration Testing

Router and InternalFirewall

Penetration Testing

Router and Switches

Penetration Testing

Internal Network

Penetration Testing

IDS

Penetration Testing

Wireless Network

Penetration Testing

Denial of Service

Penetration Testing

Password Cracking

Stolen Laptop, PDAs and Cell Phones

Social EngineeringApplication

Cont’d

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All Rights Reserved. Reproduction is Strictly Prohibited

Penetration TestingPenetration Testing Penetration TestingPenetration Testing

Penetration Testing Roadmap (cont’d)(cont d)

Cont’dPhysical Database VoIP Security

Penetration Testing

Penetration testing Penetration Testing

Virus and Trojan

Detection

War Dialing VPN Penetration Testing

Log Management

Penetration Testing

File Integrity Checking

Blue Tooth and Hand held

Device Penetration Testingg

Telecommunication And Broadband

Email Security Penetration Testing

Security Patches

Data Leakage P i T i

End Here



Communication Penetration Testing

Penetration TestingPatches Penetration Testing

Penetration Testing

File Integrity

• Whether the file is same as the original fil

File integrity checks:

file.• For any modification in the file.

File integrity can be

• Faulty storage media.

File integrity can be compromised due to:

• Transmission errors.• Committing errors during copying or

moving.• Software bugs viruses etc



• Software bugs, viruses, etc.

Integrity Checking Techniques

Comparing two files bit-by-bit:

• It requires two copies of the same file (not used normally).

CRC b d i i h ki

• The Cyclic Redundancy Check (CRC) function takes input data stream of any length and produces an output value of a certain fixed size

CRC-based integrity checking:

value of a certain fixed size.• It is used for detecting common errors caused by noise

in transmission channels by comparing the file's CRC value to a previously calculated value.

• Hash-based verification ensures that a file has not been d i l d b i h fil ' h h

Hash-based integrity checking:



corrupted or manipulated by comparing the file's hash value to a previously calculated value.

Steps for Checking File Integrity

1• Check while you unzip the file

2• Check for CRC value integrity checking

• Check for hash value integrity checking3

g y g



Step 1: Check While you Unzip the Filethe File

If you have the zip file, unzip it.y p , p

If it is not getting unzipped, then file may be corrupted.



Step 2: Check for CRC Value Integrity Checking Integrity Checking

Compute the CRC value of the file.

Compare the CRC value of the downloaded file with the given CRC value.

In Linux:

• Change the directory into the folder where the target files to be checked are placed.

• Type command crc32 ‘your_filename’ and press enter, whichdisplays:displays:• Crc32.• Filename with crc value.

• Compare the computed CRC value and the one displayed with the fil



filename.

CRC Checking in Windows

Cyclic Redundancy Check (CRC) of files is available with the Windows Cyclic Redundancy Check (CRC) of files is available with the Windows installer.

After the Windows installer finishes copying a file, it gets a CRC value from both the source and the destination files.

The installer checks the original CRC stamped into the file and compares this to the CRC calculated from the copy.

If b th th l f CRC diff t th fil b t d



If both the values of CRC are different, then file may be corrupted.

Step 3: Check for Hash Value Integrity Checking Integrity Checking

Step 1: Get the file and previously calculated hash p p yvalue for the file

Step 2: Generate a new hash value for the file

Step 3: Match the old and new hash values



Step 3.1: Get the File and Previously Calculated Hash Value for the File

Compute the hash value of the file Compute the hash value of the file before sending to anyone

Use different hash value creating tools such as md5sum and PasswordZilla



Step 3.2: Generate a New Hash Value for the FileValue for the File

Use the different hash value creating tools such as Use the different hash value creating tools such as CommuniCrypt QuickHasher to create the hash value for the downloaded file



Step 3.3: Match the Old and New Hash ValuesHash Values

Match the old and new hash values in order to check whether the file is atc t e o d a d e as a ues o de to c ec et e t e e s corrupted or safe.

If these values are not matching it means the file is corruptedIf these values are not matching, it means the file is corrupted.



File Integrity Checking Tools

• http://cfv.sourceforge.net/Cfv:

• http://www.mkssoftware.com/docs/man1/cksum.1.aspCksum:

• www.tteknik.nu/starzinger/DySFV/DySFV:

f /F S • www.fastsum.com/FastSum:

• http://trvx.com/flashsfv/FlashSFV:

• http://www.slavasoft.com/fsum/FSUM:



• http://www.slavasoft.com/hashcalc/HashCalc:

File Integrity Checking Tools (cont’d)(cont d)

• http://jpassgen.sourceforge.net/jhashcalc.jnlpjHashCalc:

• http://sourceforge.net/projects/jacksum/Jacksum:

• http://www linuxmanpages com/man1/md5sum 1 php• http://www.linuxmanpages.com/man1/md5sum.1.php• www.pc-tools.net/win32/md5sums/

Md5sum:

• http://www.linuxmanpages.com/man1/sha1sum.1.phpSha1sum:

• www.codesector.com/teracopy.aspTeraCopy:

http // checks ms so rceforge net/wxChecksums: • http://wxchecksums.sourceforge.net/wxChecksums:

• www.macupdate.com/info.php/id/23168SuperSFV:



• www.traction-software.co.uk/SFVChecker/SFV Checker:

Summary

File integrity checks if the file is same as the original file and if there are any modifications in the file.

Cyclic Redundancy Check (CRC) function takes input data stream of any l h d d l f i fi d ilength and produces an output value of a certain fixed size.

H h b d ifi ti th t fil h t b t d Hash-based verification ensures that a file has not been corrupted or manipulated by comparing the file's hash value to a previously calculated value.



lptv4 module 36 file integrity checking

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