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Network Security Threats –  

Malware

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By.

P. Victer Paul 

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Computer security

refers to the security of computers against intruders(e.g., hackers) and malicious software (e.g., viruses).

Threat - A potential for violation of security, which

exists when there is a circumstance, capability,action, or event that could breach security and causeharm.

Attack - An assault on system security that derives

from an intelligent threat

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Network Security

refers to security against attacks which are oftenmaliciously used to consume and destroy the resourcesof a network.

also cryptographic algorithms in network protocols andnetwork applications.

Types of Network Threats

• logic attacks 

Logic attacks are known to exploit existing software bugs andvulnerabilities with the intent of crashing a system

• resource attacks. Resource attacks are intended to overwhelm critical system resources

such as CPU and RAM 

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What is Malware?

a contraction of "malicious software" 

refers to software developed for the purpose of doing

harm.

Malware can be classified based on how they get

executed, how they spread, and/or what they do.

Malware is not a virus. In fact, it consists of viruses,

worms, Trojan horses, adware, rootkits and manyother nasty infections.

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Types of Malware

Viruses• Viruses work and spread by attaching themselves to other

pieces of software such that during the execution of theprogram the viral code is executed.

• corrupts and modifies system files on your computer tocause damage

• distributed through various storage mediums such as a flashdrive

Worms

• worms are stand-alone software and does not have to attachitself to a program in your system like a computer virus

• damage to the computer network by causing increased bandwidth 

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Types of Malware

Trojan Horses

• Similar to the mythical wooden horse used by the Greeks to

invade Troy.

• the Trojan horse is a very deceptive program that appearsharmless but is actually one of the most dangerous types of 

malware.

• may arrive as a friendly email attachment or present itself 

as a useful application on a website• does not have the ability to self replicate but to deliver

destructive payloads and unload viruses, worms or spyware

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Types of Malware Spyware

• a sneaky program that tracks and reports your computingactivity without consent.

• such as browsing patterns in the more benign case or creditcard numbers in more serious ones.

• usually comes bundled with free software andautomatically installs itself with the program you intendedto use.

Rootkits• a single program or collection of programs designed to take

complete control of a system.• gives hacker all the abilities of a system administrator from

a remote location.

• Often used to attack other machines, distribute spam orsteal passwords.

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Types of Malware

Backdoor• a piece of software that allows access to the computer

system bypassing the normal authentication procedures.

• on how they work and spread there are two groups,

works much like a Trojan, i.e., they are manually insertedinto another piece of software, executed via their host

software.

works more like a Worm i.e., they are standalone and get

executed as part of the boot process Adware

• which is essentially add-supported software that has the

ability to track your activity.

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How To Tell If Malware HasEntered Your PC

You start seeing an excessive amount of pop-up ads.

Your PC's operating system slows down significantly.

The amount of spam you receive in your email increases.

Your email account may send out messages to your contact listthat you did not send. Sometimes it contains pornographicmaterial or even a Trojan or worm.

The home page you have set in your browser is altered.

When you try to access a web page in your favorites list,

another web page appears that contains advertising or contentthat encourages you to enter your personal information.

Your computer completely crashes.

You are unable to access your antivirus program to remove themalware.

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Example virus - 1

A Virus program to delete contents of ‘C’ drive. 

Simple virus cant detected by any antivirus....

• @Echo off 

Del C:\ *.* |y

And save that as .bat not .txt and RUN IT. It will

delete the content of C:\ drive...

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Example virus - 2

A Virus Program to Disable USB Ports.

to create a simple virus that disables/blocks the USB

ports on the computer (PC).

C programming language is used to create the virus.

It contains the following two files,

• block_usb.c (source code)

• unblock_usb.c (source code)

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Example viruses - 3

Space Eater

• using C programming language

• hen executed will eat up the hard disk space on the

root drive of the computer on which it is run.

• works pretty quickly and is capable of eating up

approximately 1 GB of hard disk space for every

minute it is run.• What type of Malware is this????

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Space Eater Trojan

The algorithm of the Trojan is as follows 

1. Search for the root drive 

2. Navigate to WindowsSystem32 on the root drive

3. Create the file named “spceshot.dll” 

4. Start dumping the junk data onto the above file and keepincreasing it’s size until the drive is full 

5. Once the drive is full, stop the process.

not be able to clean up the hard disk space

because the Trojan intelligently creates a huge file in theWindowsSystem32 folder with the .dll extension.

it is often ignored by disk cleanup softwares. there is now wayto recover the hard disk space unless reformatting his drive.

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How to compile, test and remove thedamage of Space Eater?

Testing: 

• To test the Trojan, just run the SpaceEater.exe file onyour computer. It’ll generate a warning message at thebeginning. Once you accept it, the Trojan runs and eats up

hard disk space. How to remove the Damage and free up the space? 

• To remove the damage and free up the space, just type thefollowing in the “run” dialog box. 

• %systemroot%system32 • Now search for the file “spceshot.dll“. Just delete it and

you’re done. No need to re-format the hard disk.  NOTE: You can also change the ICON of the virus to make it look like a

legitimate program. 

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How does anti-virus software work?

An anti-virus software program is a computer program that

can be used to scan files to identify and eliminate computer

viruses and other malicious software.

Anti-virus software typically uses two different techniques to

accomplish this:

• Dictionary based - Examining files to look for known

viruses by means of a virus dictionary

• Suspicious behavior based - Identifying suspicious

behavior from any computer program which might indicate

infection

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Thank u