COEN 252 Computer Forensics - PowerPoint Presentation

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COEN 252 Computer Forensics

Phishing

Thomas Schwarz, S.J. 2006Slide2

URL Obscuring

Internet based criminal activity that subverts web technology:Phishing (fraud)

Traffic redirectionHosting of illegal sites Child pornographySlide3

URL Obscuring

Internet based fraud is gaining quickly in importance.

Phishing: The practice of enticing victims with spoofed email to visit a fraudulent webpage.

http://www.antiphishing.org/Slide4

URL Obscuring

Technical Subterfuge:Plants

crimeware onto PCs.Example: Vulnerable web browser executes remote script at a criminal website.Just staying away from porn no longer protects you.Payload:Use Trojan keylogger spyware.

Search for financial data and send it to an untraceable email addressSlide5

URL Obscuring

Social Engineering:Target receives e-mail pretending to be from an institution inviting to go to the institutions website.

Following the link leads to a spoofed website, which gathers data.It is possible to establish a web-presence without any links:Establish website with stolen / gift credit card.Use email to send harvested information to an untraceable account, etc.

Connect through public networks.Slide6

URL Obscuring

PhishingTargets general population

Thrives even with very low success rateSpear PhishingTargets individualsMore sophisticated and more expensiveIndividual success has higher valueSlide7

URL Obscuring:

Phishing Example

Visible Link: https://www.usa.visa.com/personal/secure_with_visa/index.html?t=h1_/index.html

Actual Link: http://www.verified-web-us.com/Visa%20USA%20%20Personal%20%20Protect%20Your%20Card.htm

Actual website IP: 209.35.123.41

Uses Java program to overwrite the visible address bar in the window:Slide8

URL Obscuring:

Phishing ExampleSlide9

Phishing Tendencies

Phishs currently are very unsophisticated

Sophistication does not yield much better success rateSlide10

URL Obscuring

Phishs need to hide web-serversURL Obscuring

Javascript or other active web-technology overwrites URL fieldno longer possible in latest browsersOther techniques to hide web-server address Use hosts fileHiding illegal web-server at legal siteHijacking site to host pages.Slide11

URL Basics

Phishs can use obscure features of URL.URL consists of three parts:

ServiceAddress of serverLocation of resource.

http://www.cse.scu.edu/~tschwarz/coen252_03/Lectures/URLObscuring.htmlSlide12

URL Basics

Scheme, colon double forward slash.

An optional user name and password. The internet domain name RCF1037 format IP address as a set of four decimal digits.

Port number in decimal notation. (Optional)

Path + communication data.

http://tschwarz:fiddlesticks@www.cse.scu.edu/~tschwarz/coen252_03/Lectures/URLObscuring.html

http://www.google.com/search?hl=en&ie=UTF-8&q=phishingSlide13

Obscuring URL Addresses

Embed URL in other documentsUse features in those documents to not show complete URL

http://www.usfca.edu@www.cse.scu.edu/~tschwarz/coen252_03/index.html

URL rules interpret this as a userid.

Hide this portion of the URL.Slide14

Obscuring URL Addresses

Use the password field.www.scu.edu has IP address 129.210.2.1.

Some browsers accept the decimal value 129*256**3 + 210*256**2 + 2*256 + 1 = 2178023937 for the IP address.http://www.usfca.edu@2178023937 Works as a link.Does not work directly in later versions of IESlide15

Obscuring URL Addresses

http://www.usfca.edu@129.210.2.1 works.

Hide the ASCI encoding of @:http://www.usfca.edu%40129.210.2.1Or just break up the name:http://www.usfca.edu%40%127%167w.scu.eduOr use active page technologies (javascript, …) to create fake links.Slide16

Obscuring URL Addresses

IDN – International Domain Names

Non-english Unicode characters are encoded as basic ASCII strings:punycodepunycode exampleb

űcher.ch encoded as xn- - bcher – kva.ch

Homographs: Characters from different alphabets look the same

Potential URL Obscuring

Register paypal.com, where one ‘a’ comes from a different alphabet.Slide17

Obscuring URL Addresses

Padding URLs

.. means go up create directory …http://129.210.2.1/.../../.../../.../../.../error.htmlSlide18

Obscuring URL Addresses

Redirection

Direct target redirects to main siteChances of main site getting shut down is lessTechnologiesPage-based redirection

Add meta tag to head section

<meta http-equiv=“refresh” content=“0; URL=http://bobadilla.engr.scu.edu”>

Server-based redirection

Apache: httpd.conf with a redirect statement

Redirection via vulnerable websites

2006 eBay run a script that redirected based on query string to

any

site.Slide19

'Enroll your card with Verified By Visa program'

2004 Phish sends SPAM consisting of a single image:Slide20

'Enroll your card with Verified By Visa program'

The whole text is a single image, linked to the correct citi URL.

If the mouse hovers over the image, it displays the correct citi URL.

But surrounded by an HTML box that leads to the phishing website.Slide21

'Enroll your card with Verified By Visa program'

Target webpage has an address bar that is overwritten with a picture with a different URL.

Go to www.antiphishing.org .Slide22
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Phishing

Phishers now use bogus https techniques.

Exploiting browser flaws to display secure icon.Hacking legitimate sites or frames from these sites directly.Purchase and present certificates for sites that are named in resemblance of the target sites.

The SSL lock icon is no longer a guarantee for a legitimate site.Slide25

Registrar Impersonation Phishing Attacks

Phisher

sets up a bogus registrar customer portalPhisher composes email correspondence from registrarPhisher sends email to the contact email addresses for a domain nameVictims visit bogus registrar customer portal and disclose login credentials

Phisher

collects account credentials for subsequent misuseSlide26

Registrar Impersonation Phishing Attacks

Domain name registration information is open to the public

E.g. whois for windows or linux/unixAdversary can use this information (plus web) in order to target potential victims

For example, those whose registration is close to expiration

The information is also used to enhance the credibility of the messageSlide27

Use

whoisSlide28
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Registrar Impersonation Phishing Attacks

Once authentication information is obtained

Modify DNS records to point to name servers under attacker’s controlMX: Points to mail hosts under attacker’s control and use them to send spam, …The victim was trustedAAAA

or

A

: To point to systems under attacker control

To host phony content

To provide false authentication portals Slide30

Registrar Impersonation Phishing Attacks

Fast Flux attacks

Fully qualified domain name has multiple (hundreds or even thousands) IP addresses assigned to it.Slide31

Registrar Impersonation Phishing Attacks

Counter measures taken:

Registrars limit open information severelyShould not use email to communicate with clientsSlide32

Hiding Hosts

Name Look-Up:

OS checks HOST file first.Can use HOST file to block out certain sitesadserversAffects a single machine.

OS

Location

Linux

/etc/hosts

Win95/98/ME

C:\windows\hosts

Win NT/2000/XP Pro

C:\winnt\systems32\etc\hosts

Win XP Home

C:\windows\system32\drivers\etc\hostsSlide33

Subverting IP Look-Up

In general, not used for phishing.

Economic DamageHillary for Senate campaign attack.Hiding illegal websites. (Kiddie Porn)DNS Server Sabotage IP ForwardingSlide34

Subverting IP Look-Up

Port Forwarding

URLs allow port numbers.Legitimate business at default port number.Illegitimate at an obscure port number.

Screen clicks

Embed small picture.

Single pixel.

Forward from picture to the illegitimate site.

Easily detected in HTML source code.

Password screens

Depending on access control, access to different sites.Slide35

Phisher-Finder

Carefully investigate the message to find the URL.

Do not expect this to be successful unless the phisher is low-tech.Capture network traffic with Ethereal to find the actual URL / IP address.Use Sam Spade or similar tools to collect data about the IP address.Slide36

Phisher-Finder

Capture network traffic with Ethereal when going to the site.This could be dangerous.

Disable active webpages.Do not use IE (too popular).Look at the http messages actually transmitted.Expect some cgi etc. script.Slide37

Phisher-Finder

Investigation now needs to find the person that has access to the website.

This is were you can expect to loose the trace.The data entered can be transmitted in various forms, such as anonymous email.For example, they can be sent to a free email account.IPS usually has the IP data of the computer from which the account was set up and from which the account was recently accessed.

Perpetrator can use publicly available computers and / or unencrypted wireless access points.

Investigator is usually left with vague geographical data.