{"id":5504,"date":"2020-10-22T17:04:37","date_gmt":"2020-10-22T09:04:37","guid":{"rendered":"https:\/\/www.darknet.org.uk\/?p=5504"},"modified":"2020-10-22T17:04:54","modified_gmt":"2020-10-22T09:04:54","slug":"fuzzilli-javascript-engine-fuzzing-library","status":"publish","type":"post","link":"https:\/\/www.darknet.org.uk\/2020\/10\/fuzzilli-javascript-engine-fuzzing-library\/","title":{"rendered":"Fuzzilli &#8211; JavaScript Engine Fuzzing Library"},"content":{"rendered":"<p>Fuzzilii is a JavaScript engine fuzzing library, it&#8217;s a coverage-guided fuzzer for dynamic language interpreters based on a custom intermediate language (\u201cFuzzIL\u201d) which can be mutated and translated to JavaScript.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.darknet.org.uk\/wp-content\/uploads\/2020\/10\/Fuzzilli-JavaScript-Engine-Fuzzing-Library-640x268.png\" alt=\"Fuzzilli - JavaScript Engine Fuzzing Library\" width=\"640\" height=\"268\" class=\"aligncenter size-medium wp-image-5506\" srcset=\"https:\/\/www.darknet.org.uk\/wp-content\/uploads\/2020\/10\/Fuzzilli-JavaScript-Engine-Fuzzing-Library-640x268.png 640w, https:\/\/www.darknet.org.uk\/wp-content\/uploads\/2020\/10\/Fuzzilli-JavaScript-Engine-Fuzzing-Library-1024x429.png 1024w, https:\/\/www.darknet.org.uk\/wp-content\/uploads\/2020\/10\/Fuzzilli-JavaScript-Engine-Fuzzing-Library-1536x644.png 1536w, https:\/\/www.darknet.org.uk\/wp-content\/uploads\/2020\/10\/Fuzzilli-JavaScript-Engine-Fuzzing-Library-2048x858.png 2048w\" sizes=\"(max-width: 640px) 100vw, 640px\" \/><\/p>\n<script async src=\"https:\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-3033787195489589\"\r\n     crossorigin=\"anonymous\"><\/script>\r\n<!-- Darknet Responsive Post Ad Links [previously link ad unit] -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:block\"\r\n     data-ad-client=\"ca-pub-3033787195489589\"\r\n     data-ad-slot=\"5456620019\"\r\n     data-ad-format=\"auto\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script>\n<p>When fuzzing for core interpreter bugs, e.g. in JIT compilers, semantic correctness of generated programs becomes a concern. This is in contrast to most other scenarios, e.g. fuzzing of runtime APIs, in which case semantic correctness can easily be worked around by wrapping the generated code in try-catch constructs. There are different possibilities to achieve an acceptable rate of semantically correct samples, one of them being a mutational approach in which all samples in the corpus are also semantically valid. In that case, each mutation only has a small chance of turning a valid sample into an invalid one.<\/p>\n<h2>Using Fuzzilli JavaScript Engine Fuzzing Library<\/h2>\n<p>The basic steps to use this fuzzer are:<\/p>\n<ul>\n<li>    Download the source code for one of the supported JavaScript engines. See the Targets\/ directory for the list of supported JavaScript engines.<\/li>\n<li>    Apply the corresponding patches from the target&#8217;s directory. Also see the README.md in that directory.<\/li>\n<li>    Compile the engine with coverage instrumentation (requires clang >= 4.0) as described in the README.<\/li>\n<li>    Compile the fuzzer: <code>swift build [-c release]<\/code>.<\/li>\n<li>    Run the fuzzer: <code>swift run [-c release] FuzzilliCli --profile=<profile> [other cli options] \/path\/to\/jsshell<\/code>. See also swift run <code>FuzzilliCli --help<\/code>.<\/li>\n<\/ul>\n<h3>How FuzzIl works<\/h3>\n<p>FuzzIL has a number of properties:<\/p>\n<ul>\n<li>    A FuzzIL program is simply a list of instructions.<\/li>\n<li>    A FuzzIL instruction is an operation together with input and output variables and potentially one or more parameters (enclosed in single quotes in the notation above).<\/li>\n<li>    Inputs to instructions are always variables, there are no immediate values.<\/li>\n<li>    Every output of an instruction is a new variable, and existing variables can only be reassigned through dedicated operations such as the Reassign instruction.<\/li>\n<li>    Every variable is defined before it is used.<\/li>\n<\/ul>\n<p>A number of mutations can then be performed on these programs:<\/p>\n<ul>\n<li>    InputMutator: replaces input variables of instructions with different ones to mutate the dataflow of the program.<\/li>\n<li>    CodeGenMutator: generates code and inserts it somewhere in the mutated program. Code is generated either by running a code generator or by copying some instructions from another program in the corpus (splicing).<\/li>\n<li>    CombineMutator: inserts a program from the corpus into a random position in the mutated program.<\/li>\n<li>    OperationMutator: mutates the parameters of operations, for example replacing an integer constant with a different one.<\/li>\n<li>    and more&#8230;<\/li>\n<\/ul>\n<p>You can download Fuzzilli here:<\/p>\n<p><a href=\"https:\/\/github.com\/googleprojectzero\/fuzzilli\/archive\/v0.9.1.zip\">fuzzilli-v0.9.1.zip<\/a><\/p>\n<p>Or read more <a href=\"https:\/\/github.com\/googleprojectzero\/fuzzilli\">here<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Fuzzilii is a JavaScript engine fuzzing library, it&#8217;s a coverage-guided fuzzer for dynamic language interpreters based on a custom intermediate language (\u201cFuzzIL\u201d) which can be mutated and translated to JavaScript. When fuzzing for core interpreter bugs, e.g. in JIT compilers, semantic correctness of generated programs becomes a concern. This is in contrast to most other [&hellip;]<\/p>\n","protected":false},"author":25,"featured_media":5506,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"none","_seopress_titles_title":"Fuzzilli - JavaScript Engine Fuzzing Library","_seopress_titles_desc":"Fuzzilii is a JavaScript engine fuzzing library, it&#039;s a coverage-guided fuzzer for dynamic language interpreters based on a custom intermediate language.","_seopress_robots_index":"","_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[10],"tags":[1277],"featured_image_src":"https:\/\/www.darknet.org.uk\/wp-content\/uploads\/2020\/10\/Fuzzilli-JavaScript-Engine-Fuzzing-Library.png","featured_image_src_square":"https:\/\/www.darknet.org.uk\/wp-content\/uploads\/2020\/10\/Fuzzilli-JavaScript-Engine-Fuzzing-Library.png","author_info":{"display_name":"Darknet","author_link":"https:\/\/www.darknet.org.uk\/author\/darknet\/"},"_links":{"self":[{"href":"https:\/\/www.darknet.org.uk\/wp-json\/wp\/v2\/posts\/5504"}],"collection":[{"href":"https:\/\/www.darknet.org.uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.darknet.org.uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.darknet.org.uk\/wp-json\/wp\/v2\/users\/25"}],"replies":[{"embeddable":true,"href":"https:\/\/www.darknet.org.uk\/wp-json\/wp\/v2\/comments?post=5504"}],"version-history":[{"count":0,"href":"https:\/\/www.darknet.org.uk\/wp-json\/wp\/v2\/posts\/5504\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.darknet.org.uk\/wp-json\/wp\/v2\/media\/5506"}],"wp:attachment":[{"href":"https:\/\/www.darknet.org.uk\/wp-json\/wp\/v2\/media?parent=5504"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.darknet.org.uk\/wp-json\/wp\/v2\/categories?post=5504"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.darknet.org.uk\/wp-json\/wp\/v2\/tags?post=5504"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}