Friday, 2 May 2014

eBay Covert Redirect Vulnerability Based on Googleads.g.doubleclick.net

The vulnerability occurs at "ebay.com/rover" page with "&mpre" parameter, i.e.
http://rover.ebay.com/rover/1/711-67261-24966-0/2?mtid=691&kwid=1&crlp=1_263602&itemid=370825182102&mpre=http://www.google.com


The vulnerability can be attacked without user login. Tests were performed on Firefox (26.0) in Ubuntu (12.04) and IE (9.0.15) in Windows 7.




1) When a user is redirected from eBay to another site, eBay will check whether the redirected URL belongs to domains in eBay's whitelist, e.g.
google.com
facebook.com
linkedin.com

If this is true, the redirection will be allowed.

However, if the URLs in a redirected domain have open URL redirection vulnerabilities themselves, a user could be redirected from eBay to a vulnerable URL in that domain first and later be redirected from this vulnerable site to a malicious site. This is as if being redirected from eBay directly.


One of the vulnerable domain is,
http://googleads.g.doubleclick.net (Google's Ad system)






(2) Use one of webpages for the following tests. The webpage address is "http://www.tetraph.com/essaybeans/reflections/solitude.html". Can suppose that this webpage is malicious.





Vulnerable URL:
http://rover.ebay.com/rover/1/711-67261-24966-0/2?mtid=691&kwid=1&crlp=1_263602&itemid=370825182102&mpre=http://www.google.com

POC:
http://rover.ebay.com/rover/1/711-67261-24966-0/2?mtid=691&kwid=1&crlp=1_263602&itemid=370825182102&mpre=http://googleads.g.doubleclick.net/aclk?sa=L%26ai=C-RHnNvn2Uom8LeTaigfjkIHICfLQnccEAAAQASAAUNTx5Pf4_____wFgvwWCARdjYS1wdWItMDQ2NjU4MjEwOTU2NjUzMsgBBOACAKgDAaoEhQFP0LHofgVzg8U9Bvwu2_hN9Ow0n2tBH9xjKtngqcF6hgGQpxV6QzMgNxx0_UawPG3-UD097GLLCirbVMl2QxQqa04U3cp4YFgV5dshYbzmqlVVfNn-NuunzLNab6ATE5BUwQ9bgXBOW_qEz8qgbwVOvUJrn1IzL-ymANaKsQLZ9POlkbIe4AQBoAYV%26num=0%26sig=AOD64_3a3m_P_9GRVFc6UIGvnornMcLMoQ%26client=ca-pub-0466582109566532%26adurl=http://www.tetraph.com/essaybeans/reflections/solitude.html

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