web spam final

8/2/2019 Web Spam Final

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UNDER THE GUIDANCE OF

MR. KHASIM D VALI

NAVYA R

8th SEM CS


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CONTENTSWhat is web spam?

Boosting techniques

Term spamming techniques and targets Link spamming techniques

Hiding techniques

Major types of spamming

Spam filters

Conclusion


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What is web spam?

Spamming is any deliberate action solely inorder to boost a web pages position in search

engine results, regardless of the pages real value Spam = web pages that are the result of

spamming

Approximately 10-15% of web pages are spam


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Web spam taxonomy

Boosting techniques

Techniques to achieve high relevance or

importance for some pages.

Hiding techniques

Techniques to hide the adopted boostingtechniques from human web users.


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Boosting techniques

Term spamming

Manipulating the text/fields of web pages in

order to appear relevant to queries

Link spamming

Creating link structures that boost page rank


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Cont.


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Term spamming

Target algorithms


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Techniques

Repetition of one or a few specific terms e.g., free, cheap

increase relevance for a document with respectto a small number of query terms

Dumping of a large number of unrelated terms

e.g., copy entire dictionaries

Weaving Copy legitimate pages and insert spam terms

at random positions


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Term spam targets

Body of web page

TitleHTML meta tags

Anchor text

URL


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Link spam

There are three kinds of web pages from aspammers point of view

Inaccessible pages

Accessible pages

e.g., web blog comments pages

spammer can post links to his pages

Own pages

Completely controlled by spammer.

Group of own pages known as spam farm.


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Target algorithms

Hypertext Induced Topic Search (HITS)algorithm

Hub scores A spammer should add many outgoing links to

the target page t to increase its hub score

Authority scores Having many incoming links from presumably

important hubs


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Cont.

PageRank

Uses incoming link information to assignnumerical weights to all pages on the web

Numerical weight that it assigns to any givenelement Eis also called the PageRank of Eanddenoted byPR(E)

Spammers manipulate the algorithm using links


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Targets and Techniques

Outgoing links

Directory cloning

Incoming links

Create a honey pot

Infiltrate a web directory

Post links to unmoderated message boards orguest books


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Hiding techniques

Content hiding

Use same color for text and page background

Spam terms or links on a page can be madeinvisible when the browser renders the page

Cloaking Return different page to crawlers and browsers


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MAJOR TYPES OF SPAMMING

Email spam

Blog spamSocial networking spam

Text spam


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FILTERS TO DETECT SPAMA spam filter is a web-based program which helps toprevent spam e-mail from entering your inbox.

Password filter

Blacklist and whitelist filters

Challenge/response filter

Rules-based filter

Community-based filter

Adaptive/Bayesian filter


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CONCLUSIONIdentify instances of spam, i.e., find pages that

contain specific types of spam, and stop crawling

and/or indexing such pages.

Prevent spamming, that is, making specific

spamming techniques impossible to use.

Counterbalance the effect of spamming


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web spam final

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