CMU Usable Privacy and SecurityLaboratory

http://cups.cs.cmu.edu/

Phinding Phish: An Evaluation of Anti-Phishing Toolbars

Yue Zhang, Serge Egelman, Lorrie Cranor, and Jason Hong

• CMU Usable Privacy and Security Laboratory • http://cups.cs.cmu.edu/

Anti-Phishing Tools 84 Listed on download.com (Sept. ‘06)

Included in many browsers

Poor usability• Many users don’t see indicators• Many choose to ignore them• But usability is being addressed

Are they accurate?

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Tools Tested CallingID

Cloudmark

EarthLink

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Tools Tested eBay

Firefox

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Tools Tested IE7

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Tools Tested Netcraft

Netscape

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Tools Tested SpoofGuard

TrustWatch

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Source of Phish High volume of fresh phish

• Sites taken down after a day on average• Fresh phish yield blacklist update information

Can’t use toolbar blacklists

We experimented with several sources• APWG - high volume but many duplicates and legitimate

URLs included• Phishtank.org - lower volume but easier to extract phish• Assorted other phish archives - often low volume or not

fresh enough

• CMU Usable Privacy and Security Laboratory • http://cups.cs.cmu.edu/

Phishing Feeds Anti-Phishing Working Group

• reportphishing@antiphishing.org• ISPs, individuals, etc.• >2,000 messages/day• Filtering out URLs from messages

PhishTank• http://www.phishtank.org/• Submitted by public• ~48 messages/day• Manually verify URLs

• CMU Usable Privacy and Security Laboratory • http://cups.cs.cmu.edu/

Testbed for Anti-Phishing Toolbars

Automated testing

Aggregate performance statistics

Key design issue:• Different browsers• Different toolbars• Different indicator types

Solution: Image analysis• Compare screenshots with known states

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Phish!!

Warning!!

Image-Based Comparisons Two examples: TrustWatch and Google

TrustWatch:

Google:

ScreenShot

ScreenShot

VerifiedNot verified

• CMU Usable Privacy and Security Laboratory • http://cups.cs.cmu.edu/

Testbed System Architecture

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Testbed System ArchitectureRetrieve Potential Phishing SitesRetrieve Potential Phishing Sites

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Testbed System Architecture

Send URL to WorkersSend URL to Workers

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Testbed System Architecture

Worker Evaluates Worker Evaluates Potential Phishing SitePotential Phishing Site

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Testbed System Architecture

Task Manager Task Manager Aggregates ResultsAggregates Results

• CMU Usable Privacy and Security Laboratory • http://cups.cs.cmu.edu/

Experiment Methodology Catch Rate: Given a set of phishing URLs, what percentage of them are

correctly labeled as phish by the tool - count block and warning only

- taken down sites removed

False Positives: Given a set of legitimate URLs, what percentage of them are

incorrectly labeled as phish by the tool - count block and warning only

- taken down sites removed

• CMU Usable Privacy and Security Laboratory • http://cups.cs.cmu.edu/

Experiment 1 PhishTank feed used Equipment:

• 1 Notebook as Task Manager• 2 Notebooks as Workers

10 Tools Examined:• CloudMark• Earthlink• eBay• IE7• Google/Firefox• McAfee• Netcraft• Netscape• SpoofGuard• TrustWatch

• CMU Usable Privacy and Security Laboratory • http://cups.cs.cmu.edu/

Experiment 1 100 phishing URLs

• PhishTank feed• Manually verified• Re-examined at 1, 2, 12, 24 hour intervals• Examined blacklist update rate (except w/SpoofGuard)• Examined take-down rate

514 legitimate URLs• 416 from 3Sharp report• 35 from bank log-in pages• 35 from top pages by Alexa• 30 random pages

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Experiment 2 APWG phishing feed 9 of the same toolbars tested + CallingID Same testing environment

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Results of Experiment 1

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 12 24

cloudmarkearthlinkeBayfirefox w/googleie7mcafeenetcraftnetscapespoofguardtrustwatch

• CMU Usable Privacy and Security Laboratory • http://cups.cs.cmu.edu/

Results of Experiment 2

0%

10%

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30%

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50%

60%

70%

80%

90%

100%

0 1 2 12 24

cloudmarkearthlinkeBayfirefox w/googleie7callingIDnetcraftnetscapespoofguardtrustwatchfirefox

• CMU Usable Privacy and Security Laboratory • http://cups.cs.cmu.edu/

False Positives

Toolbar False Positive

SpoofGuard 218 (42%)

CallingID 10 (2%)

Cloudmark 5 (1%)

EarthLink 5 (1%)

Not a big problem for most of the toolbars

• CMU Usable Privacy and Security Laboratory • http://cups.cs.cmu.edu/

Overall findings No toolbar caught 100%

Good performers:• SpoofGuard (>90%)

Though 42% false positives

• IE7 (70%-80%)• Netcraft (60%-80%)• Firefox (50%-80%)

Most performed poorly:• Netscape (10%-30%)• CallingID (20%-40%)

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More findings Performance varied with feed

• Better with Phishtank: Cloudmark, Earthlink, Firefox, Netcraft

• Better with APWG: eBay, IE7, Netscape

• Almost the same: Spoofguard, Trustwatch

Different increases over time• More increases on APWG• Reflects the “freshness” of URLs

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CDN Attack Many tools use blacklists

Many examine IP addresses (location, etc.)

Proxies distort URLs• Used Coral CDN• Append .nyud.net:8090 to URLs• Uses PlanetLab

Works on:• Cloudmark• Google• TrustWatch• Netcraft• Netscape

• CMU Usable Privacy and Security Laboratory • http://cups.cs.cmu.edu/

Page Load Attack Some wait for page to be fully loaded

• SpoofGuard• eBay

Insert a web bug taking infinite load time• 5 lines of PHP• 1x1 GIF• Infinite loop spitting out data very slowly

Tool stays in previous state

Unable to indicate anything

• CMU Usable Privacy and Security Laboratory • http://cups.cs.cmu.edu/

Conclusion Tool Performance

• No toolbars are perfect• No single toolbar will outperform others• Heuristics have false positives

Whitelists? Hybrid approach?

Testing Methodology• Get fresher URLs• Test other than default settings

User interfaces• Usability is important

Traffic light? Pop up message? Re-direct page?

CMU Usable Privacy and Security Laboratory

http://cups.cs.cmu.edu/