29
votes
6answers
33k views

How to scan a PDF for malware?

Can anyone suggest an automated tool to scan a PDF file to determine whether it might contain malware or other "bad stuff"? Or, alternatively, assigns a risk level to the PDF? I would prefer a free ...
15
votes
3answers
15k views

Does X-Content-Type-Options really prevent content sniffing attacks?

In Tangled Web Michal Zalewski says: Refrain from using Content-Type: application/octet-stream and use application/binary instead, especially for unknown document types. Refrain from returning ...
15
votes
4answers
1k 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 ...
10
votes
3answers
11k 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. ...
12
votes
3answers
4k 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 ...
2
votes
6answers
13k views

Use PHP to check uploaded image file for malware?

I want my users to be able to upload a photo. Currently I am not checking the uploaded photo for problems of any kind, although I do limit the size to 32k. Is there any way for me to check uploaded ...
9
votes
4answers
1k views

Preventing insecure webapp on subdomain compromise security of main webapp

I want your help on getting more concrete information on a type of vulnerability that I remember vaguely. I vaguely remember hearing about a year ago that if you set up a webapp on a subdomain, and ...
6
votes
5answers
1k views

How should I serve untrusted / unsanitized documents (PDF, DOC, XLS) to end users over the web?

My website will be hosting documents for end users and I would like to make this as secure as possible. Question Assuming that I have a need to share documents on a website that may contain hostile ...
6
votes
3answers
2k views

Security/Malware implications of storing data in a BLOB as opposed to the file system

From a programming perspective, there has long been a debate over whether to store files in a BLOB or Binary field in a database, or on the file system. The debate always seems to center around ...
1
vote
4answers
846 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 (...
3
votes
3answers
916 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
432 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 ...