Linked Questions

151
votes
4answers
24k views

Which security measures make sense for a static web site?

I have a static web site. Users cannot log in or perform any other actions. Which of the common HTTP security measures make sense for my site? Do I need any of these? HTTPS Strict transport security ...
32
votes
5answers
14k views

What are the security risks of letting the users upload content to my site?

As a web designer (not a security expert) I wonder: If I allow users to upload content to my website (videos, images and text files), what are the real risks involved?
26
votes
3answers
8k views

How can I be protected from pictures vulnerabilities?

I've just read this question What is the corrupted image vulnerability? How does it work? (GIFAR, EXIF data with javascript, etc..) I'm asking myself how can I protect myself and my website's users. ...
19
votes
4answers
10k views

Is it safe to serve any user uploaded file under only white-listed MIME content types?

Let's say I develop an application that, Allows any user to upload a file of only white listed mime content type and extensions (word and pdf). Serves those files with the allowed extension and ...
19
votes
4answers
2k views

Is it safe to store and replay user-provided mime types?

If a user uploads a file but modifies the request by setting the mime-type to something arbitrary, like "superdangerous/blackhatstuff", is it safe for me to send the same mime type back to a different ...
17
votes
3answers
6k views

Using file extension and MIME type (as output by file -i -b) combination to determine unsafe files?

We allow users to upload a number of files, all of which we either send over to scribd (doc, xls, ppts, etc) or display as a video ourselves (flv, mov, mp4, etc in flowplayer). To avoid users ...
27
votes
2answers
8k views

Guidance for implementors of HTTPS-only sites (Server side)

The recent trend in HTTPS attacks is to attack the HTTP protocol. What should I do to increase my site's security if the only protocol I want is HTTPS? Some easy to implement ideas are Implement ...
13
votes
3answers
19k views

Is it possible to inject HTML into image to provoke XSS?

Some answers mention that it's possible to inject attacker-controlled HTML into images and therefore provoke XSS. I guess that this HTML will be processed by browser only if hole exists in browser. ...
9
votes
2answers
4k views

Why should I restrict the content type of files be uploaded to my site?

We are building an application where users can upload resumes in our system for our administrators to download. We are having a debate about restricting the content type of the files that can be ...
9
votes
2answers
3k views

MIME sniffing protection

As it is known, older versions of MSIE (before 8) have a nasty habit of treating images as HTML if they "look like" HTML, which can lead to nasty vulnerabilities for sites that allow people to upload ...
2
votes
4answers
2k views

Security risks of hosting user-supplied images?

I have a program that will accept and fetch images from urls. It will check if the extension is .png, .jpg, etc... I will fetch these files and store them, they will be shown to users in a gallery (...
4
votes
3answers
2k views

Flash ignores Content-Type header, allowing XSS?

I recently read that the Flash plugin ignores the Content-Type header in certain circumstances. In particular, you can give Flash a URL, and the Flash plugin will happily fetch the content at that ...
2
votes
1answer
540 views

How confident is MIME blacklisting on a proxy server?

We are blacklisting a number of MIME types on our proxy server so users can't download certain file types, for example, executables. Could it be possible that somehow, a malicious server can trick a ...
1
vote
2answers
275 views

How to make this script run from image?

I'm testing my application for security vulnerabilities. I've inserted javascript in a gif and uploaded it into the application. The application loads the image in <img> tag. The script gets ...