![]() ![]() Web servers use these kinds of configuration files when present, but you're not normally allowed to access them using HTTP requests. If the server trusts the content-type in the HTTP request an attacker could change this value to “image/jpeg” which would pass the validation. The syntax for such a command would look something like this: curl -X POST -F "submit=" -F If you like the command line you can achieve the same result with curl. Now in order to bypass this you can simply pass the request to a proxy and modify the file type once its passed the browsers checks. Here we can see the file is checked whether the mime type is a pdf The reason this occurs is because there is something called Client-Side Validation occurring. One thing you may come across often is an error message along the lines of "Only JPEG files allowed" before you even send the upload request. By default it has a burp collaborator instance placed in the payload but you can change that to wherever you want. Note #2: You may also want to adjust the payload inside the file. ![]() This allows for a focused attack with clear results. Notice how he wisely chose only those two options during the attack. ![]() In the video linked below, Stok used the tool to target XXE inside PDF files. Reference the list of top 10 impacts via file upload to get an idea of how to attack the server. Note: I believe its important to know which attacks to try before sending 10000 different payloads and file types. There is a slight learning curve to use the tools full capabilities however if you just want to throw some basic tests its pretty simple. If you are looking for automation I would highly suggest using the burpsuite extension called file upload scanner. HTML / JS : HTML injection / XSS / Open redirect.ASP / ASPX / PHP5 / PHP / PHP3: Webshell / RCE.Top 10 Things To Achieve With File Upload My goal is to focus on making the task simple and straight forward. This motivated me to create a relevant guide to file upload attacks. After some trial and error I finally succeeded in bypassing the filter but prepending some PDF magic bytes PDF%PDF- to the beginning of the file content and together with the double file type the file was successfully uploaded. I tried to bypass the filter by appending a second filetype to the filename But I still received an error. This past week I had the opportunity to test a file upload feature which only allowed pdf files to be uploaded. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |