{"id":79,"date":"2009-03-17T13:24:59","date_gmt":"2009-03-17T21:24:59","guid":{"rendered":"http:\/\/blog.mozilla.org\/security\/?p=79"},"modified":"2009-03-17T13:24:59","modified_gmt":"2009-03-17T21:24:59","slug":"new-css-grammar-fuzzer","status":"publish","type":"post","link":"https:\/\/blog.mozilla.org\/security\/2009\/03\/17\/new-css-grammar-fuzzer\/","title":{"rendered":"New CSS Grammar Fuzzer"},"content":{"rendered":"<p>Mozilla&#8217;s Jesse Ruderman just <a href=\"http:\/\/www.squarefree.com\/2009\/03\/16\/css-grammar-fuzzer\/\">blogged<\/a> about a new CSS grammar fuzzer of his, to go along with the JS fuzzer we announced <a href=\"http:\/\/www.squarefree.com\/2007\/08\/02\/introducing-jsfunfuzz\/\">a while ago<\/a>.<\/p>\n<p>Fuzzers are a tool that we&#8217;ve found incredibly valuable in the past, and continue to employ heavily. A fuzzer&#8217;s job is to make your application fail by feeding it surprising inputs. The good ones do this by knowing a part of your code well enough that they can make smart guesses about how to confuse it. This one, for instance, produces a constant stream of mostly-correct CSS rules, and watches to see whether the browser can cope with them. Because fuzzers take these random paths, they can uncover subtle bugs that are rarely encountered during &#8220;normal&#8221; testing; and Jesse is a master at building them.<\/p>\n<p>When Jesse originally started talking about his javascript fuzzer, <a href=\"http:\/\/blog.mozilla.org\/security\/2007\/08\/06\/feedback-from-opera-on-mozilla-javascript-fuzzer\/\">he gave it to other browser vendors<\/a> first, and he&#8217;s done the same with this one. If you&#8217;re interested in automated security analysis tools though, he&#8217;s now made it public, and I recommend <a href=\"http:\/\/www.squarefree.com\/2009\/03\/16\/css-grammar-fuzzer\/\">checking it out<\/a>.<\/p>\n<p>Johnathan Nightingale<br \/>\nHuman Shield<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Mozilla&#8217;s Jesse Ruderman just blogged about a new CSS grammar fuzzer of his, to go along with the JS fuzzer we announced a while ago. Fuzzers are a tool that &hellip; <a class=\"go\" href=\"https:\/\/blog.mozilla.org\/security\/2009\/03\/17\/new-css-grammar-fuzzer\/\">Read more<\/a><\/p>\n","protected":false},"author":107,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[69],"tags":[542,45514],"coauthors":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>New CSS Grammar Fuzzer - Mozilla Security Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/blog.mozilla.org\/security\/2009\/03\/17\/new-css-grammar-fuzzer\/\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Johnathan Nightingale\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/blog.mozilla.org\/security\/2009\/03\/17\/new-css-grammar-fuzzer\/\",\"url\":\"https:\/\/blog.mozilla.org\/security\/2009\/03\/17\/new-css-grammar-fuzzer\/\",\"name\":\"New CSS Grammar Fuzzer - 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