Logical Security threats

Logical security

Protects computer-based data from software-based and communications-based threats.

Activity Least some of the logical security

threats that you know ?

Virus , backdoors, bombs , Worms, Bots, Trojans’ , spywares……

Generally , known as Malicious

Software

Malicious Softwareprograms exploiting system

vulnerabilities.Also known as malware. Types:

◦program fragments that need a host program e.g. viruses, logic bombs, and backdoors

◦independent self-contained programs e.g. worms, bots

◦replicating or notsophisticated threat to computer

systems !

You must know !In 1983, graduate student Fred

Cohen first used the term virus in a paper describing a program that can spread by infecting other computers with copies of itself !

In 1986, The Brain virus was the first virus designed to infect personal computer systems. ◦by infecting floppy disks !

Viruses: intro.piece of software that infects

programs(host)◦ modifying them to include a copy of the virus◦ so it executes secretly when host program is run

Usually specific to operating system◦ taking advantage of their details and weaknesses

a typical virus goes through phases of:◦Dormant: idle (not found in all virus) ◦Propagation: copy itself into other programs/disk

areas ◦Triggering: activated ( date, file, disk limit) ◦Execution: perform the intended

function(message, damage..

Activity Is their any similarity between computer and

biological virus ? A biological virus is a shell filled with genetic

material that injects into a living cell, infecting it. The cell then starts manufacturing copies of the virus.

A computer virus behaves similarly. It injects its contents, which is a short computer program, into a host computer, thereby infecting it. When the computer executes the virus code, it replicates the code, and also performs a task, normally damaging files or another software component of the computer

Virus Structurecomponents:

◦Infect - enables replication◦Trigger - event that makes payload

activate◦Payload - what it does

prepended / postpended / embedded

when infected program invoked, executes virus code then original program code

Virus Structure: pseudo-code

Virus Structure…Signatures –sequence of bits

that can be used to accurately identify the presence of a particular virus.

The code consists of three stages,◦activation/trigger , ◦replication/infect , and ◦Operation/payload

Virus Payloadmalicious “task” of a virus. performed when the triggering

condition is satisfied. types :

◦display a message, such as “Gotcha,” a political slogan, or a commercial advertisement

◦read a certain sensitive or private file. Such a virus is in fact spyware.

◦slow the computer down by monopolizing and exhausting limited resources.

◦ completely deny any services to the user.

Virus Payload…erase all the files on the host computerselect some files at random and change

several bits in each file, also at random. ◦referred to as data diddling, may be more

serious, because it results in problems that seem to be caused by hardware failures, not by a virus.

One step beyond data diddling is random deletion of files

random change of permissions.Produce sounds, animation.

Infection strategies two types :Nonresident viruses:

◦ search for other hosts that can be infected, ◦ infect those targets, ◦ transfers control to the infected program

Resident viruses◦do not search for hosts when they are

started. Instead, it loads itself into memory on execution and transfers control to the host program.

◦The virus stays active in the background and infects new hosts when those files are accessed by other programs or the operating system itself

Trigger Date or timeNumber of bootsGeneration counter of the virusNumber of key presses on the keyboardAmount of free space on the hard driveAmount of minutes the machine has

been idleName of an executed programBasically any event it the PC can be

used as a trigger by a virus !.

Virus ClassificationBy targetboot sector: Infects a master boot

record or boot record and spreads when a system is booted from the disk containing the virus.

file infector: Infects executable files macro virus: Infects files with

macro code that is interpreted by an application.

File infector :two types

Virus ClassificationBy Hiding Methodsencrypted virus: creates a random

encryption key, stored with the virus, and encrypts the remainder of the virus. Then, the virus uses the stored random key to decrypt the virus . virus replicates, a different random key is selected.

stealth virus: designed to hide itself from detection by antivirus software.

By restoring the size, modification date, and checksum of the infected file

encrypted virus

stealth virus

Virus Classification….Polymorphic virus: mutates and

infects each new file as a different string of bits making detection by the “signature” of the virus impossible.

Metamorphic virus: As with a polymorphic virus ,a metamorphic virus mutates with every infection.

The difference is that a metamorphic virus rewrites itself completely at each iteration, increasing the difficulty of detection

Virus Classification….A virus can modify itself and

become a different string of bits simply by inserting several nop instructions in its code.

A nop (no operation) is an instruction that does nothing.

Virus Classification….Compression virus: In addition

to mutating, a virus may hide itself in a compressed file in such a way that the bits with the virus part depend on the rest of the infected file and are therefore always different.

Compression Virus

E-Mail Virusesmore recent developmente.g. Melissa

◦exploits MS Word macro in attached doc

◦if attachment opened, macro activates

◦sends email to all on users address list

◦and does local damagethen saw versions triggered

reading emailhence much faster propagation

Virus CountermeasuresAnti-virusprevention - ideal solution but

difficultrealistically need:

◦detection◦identification◦removal

if detect but can’t identify or remove, must discard and replace infected program

Tail chasing effect

The conclusion is that as many active processes as possible should be stopped before any attempt is made to clean viruses from a computer

Anti-Virus Evolutionvirus & antivirus tech have both

evolvedearly viruses simple code, easily

removedas become more complex, so

must the countermeasuresgenerations

◦first - signature scanners◦second – heuristics rule (structure)◦third - identify actions◦fourth - combination packages

Propagation Using infected programs. the virus is

executed every time the program is executed.Using interrupts that occurs each time an

external disk drive or a DVD is inserted into a USB port. Once this interrupt occurs, the virus is executed as part of the interrupt-handling routine and it tries to infect the newly inserted volume.

As an email attachment.Through infected softwares. useful program

(a calculator, a nice clock, or a beautiful screen saver), embed a virus or a Trojan horse in it.

Usually Sharing: Each time users share a computing resource such as a disk, a file, or a library routine, there is the risk of infection

Worms, Trojans,…

Worms Self-replicating program, similar to

virus, but is self-contained.Usually propagates over network.

◦ using email, remote exec, remote login by exploiting service

vulnerabilities.It often creates denial of service

Worms …has phases like a virus:

◦dormant, propagation, triggering, execution

◦propagation phase: searches for other systems, connects to it, copies self to it and runs

1st implemented by Xerox Palo Alto labs in 1980’s◦search for idle systems to use to run

a computationally intensive task.

What makes it different ?A virus propagates when users send email, launch programs, or carry storage media between computers.

A worm propagates itself throughout the Internet by exploiting security weaknesses in applications and protocols we all use.

Has the highest speed of propagation.

Worm Propagation Model

Worm damages future worms may pose a threat to the Internet, to E-commerce, and to computer communications and this threat may be much greater and much more dangerous than that posed by other types of malicious software.

Worm damage scenariosWorm that has infected several

million computers on the Internet may have the potential for a global catastrophe.◦could launch vast DoS attacks . That

can bring down not only E-commerce sites, but sensitive military sites or the root domain name servers of the Internet.

Morris Wormone of best know wormsreleased by Robert Morris in 1988various attacks on UNIX systems

◦discover other hosts◦cracking password file to use

login/password to logon to other systems◦exploiting a bug in the finger protocol◦exploiting a bug in sendmail.

if succeed have remote shell access◦sent bootstrap program to copy worm

over

Other Worm AttacksCode Red: July 2001

◦ exploiting Microsoft Internet Information Server (IIS) bug to penetrate and spread

◦probes random IP address◦does DDoS attack ◦activities and reactivates periodically◦consumes significant net capacity when active◦infected nearly 360,000 servers in 14 hours

Code Red II variant includes backdoor◦allowing a hacker to direct activities of victim

computers

Other Worm AttacksSQL Slammer: early 2003

◦attacks MS SQL Server◦compact and very rapid spread

Mydoom: 2004◦mass-mailing e-mail worm◦installed remote access backdoor in infected systems

◦flooded the Internet with 100 million infected messages in 36hrs

Mobile Phone Wormsfirst appeared on mobile phones

in 2004◦target smartphone which can install

softwarethey communicate via Bluetooth

or MMSdisable phone, delete data on

phone, or send premium-priced messages

E.g. CommWarrior, launched in 2005◦replicates using Bluetooth to nearby

phones◦and via MMS using address-book

numbers◦copies itself to the removable memory card

Recent Malware attack

Worm TechnologyPresent highest level of development

Multiplatform: not only windowsmulti-exploit: browsers, e-mail, serversultrafast spreading: prior Internet IP scan Polymorphic: different codes per attackMetamorphic: different behavior patternstransport vehicles: for other malwareszero-day exploit : unknown vulnerability

Worm Countermeasuresanti-virusworms also cause significant net activityworm defense approaches include:

◦ signature-based worm scan filtering◦ filter-based worm containment: content/code◦ payload-classification-based worm containment examine packets using anomaly detection techniques

◦ threshold random walk scan detection exploits randomness in picking destinations to connect

◦ rate limiting and rate halting limits the rate of scanlike traffic from an infected host immediately blocks outgoing traffic when a threshold is

exceeded

Trojan Horseapparently useful , program with hidden

side-effects which is usually superficially attractive

◦ E.g. game, software upgrade, screen saver etc

when run performs some additional tasks

Usually designed primarily to give hackers access to system

often used to propagate a virus/worm or install a backdoor

or simply to destroy data

Damages Download files to the infected

computer.Make registry changes to the infected

computer. Delete files on the infected computer. Disable a keyboard, mouse, or other

peripherals. Shut down or reboot the infected

computer. Run selected applications or terminate

open applications. Disable virus protection or other

computer security software

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Other types Back doors/Trap doors

◦ It is a program that allows attackers to access a system, bypassing the normal authentication mechanisms

Bomb◦ It is a program which lies dormant until a

particulate date/time or a program logic is activated

◦ Logic bomb or Time bomb

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Types of Malware…Spywares

◦are programs, cookies, or registry entries that track your activity and send that data off to someone who collects this data for their own purposes

◦The type of information stolen varies considerably email login details IP and DNS addresses of the computer users’ Internet habits bank details used to access accounts or make online

purchases etc…

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Types of Malware…Adware

◦ is software that is installed on your computer to show you advertisements

◦ These may be in the form of pop-ups, pop-unders, advertisements embedded in programs, or placed on top of ads in web sites, etc

Key logger◦ is a program that captures and records user keystrokes◦ E.g. whenever a user enters a password, bank account

numbers, credit card number, or other information, the program logs the keystroke

◦ The keystrokes are often sent over the Internet to the hacker

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Types of Malware…Dialers

◦ are programs that set up your modem connection to connect to the Internet often to charge illicit phone usage fees

◦ are targeted to users of dial up internet servicesSpam

◦ is unsolicited bulk e-mail which is sent in massive quantities to unsuspecting Internet email users.

◦ Most spam tries to Sell products and services.

◦ A more dangerous category of spam tries to Convince the recipient to share their bank account numbers, credit

card numbers, or logins & passwords to their online banking systems/services

◦ It is also used for phishing and to spread malicious code

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Types of Malware…Rootkit

◦ is a set of tools and utilities that a hacker can use to maintain access once they have hacked a system.

◦ The rootkit tools allow them conceal their actions by hiding their files and processes and erasing their activity

Bot/Zombie◦ These are small programs that are inserted on

computers by attackers to allow them to control the system remotely without the user’s consent or knowledge

◦ Botnets :groups of computers infected by bots and controlled remotely by the owner of the bots

◦ Computers that are infected with a bot are generally referred to as zombies

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Types of Malware…Exploit

◦ it a piece of software, a command, or a methodology that attacks particular security vulnerability

◦ takes advantage of a particular weakness e.g. OS, application programs

Phishing◦ is not an application. It's the process of

attempting to acquire sensitive user information with fake websites.

◦ It's an example of social engineering techniques used to fool users

◦ Common targets for phishing Online payment systems such as e-bank, e-

commerce are

Home workRead about the following topics :

◦Famous virus attacks◦Virus writers ◦Self replicating programs (Quines)◦Different types of virus naming.◦CPU interrupts ◦Multiple-threat malwares◦Registry files◦GD Scanners