Questions tagged [file-upload]
File upload means sending a file from a local system to a remote system such as a server or another client with the intent that the remote system should store a copy of the file being transferred.
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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.
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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 ...
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4
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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 ...
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What steps should be taken to validate user uploaded images within an application?
Recently I have worked on a number of applications that need to process user uploaded images steps have been taken to validate the extension and the mime type.
But what else can be done to ensure ...
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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 ...
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5
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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?
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Risks of a PHP image upload form
My client wants a photography site where users can upload their photos in response to photography competitions. Though technically this isn't a problem, I want to know the risks associated with ...
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20
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3
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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 ...
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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 ...
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IMG tag vulnerability
Is it safe to display images from arbitrary domains? I.e. let's say I have an image on my page:
<img src="http://badguy.com/image.gif" />
What if image.gif will return some js attack vector, ...
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What is the next step of this file upload attack?
Yesterday I discovered somebody had uploaded this PHP code to my server as a .jpg file via my asp.net MVC application's "Upload your profile picture" form. I believe the attack was unsuccessful for a ...
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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 ...
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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. ...
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Secure Image Upload, or Bypassing PHP mime-type Check
When securing image uploads there are basically three approaches I know of (of course, ideally, all three are used):
check file extension
store uploaded files in non-executable directory outside the ...
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Exploits or other security risks with SVG upload?
I have a site, where people can upload graphics, you might think of it like an image hoster or a forum for pictures.
Now, I allow upload of raster graphics to a certain size, but no vector graphics ...
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10
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Antivirus for scanning anonymous file uploads
Since I have no experience with AV solutions on Unix-like environments, I would need help with suggestions on something that can be suitable for scanning files that are uploaded by anonymous users ...
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Is it necessary to scan users' file uploads by antivirus?
Web application allows users to upload files. Is it necessary to scan those files by antivirus?
I'd want to hear answer in two scenarios:
Type of file isn't checked when uploading. They are stored ...
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3
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is it safe to allow external images to be attached to Blog or any Web content?
I am filtering all images that attached to any content of my blog:
Check for file extension.
Check content type using $finfo = finfo_open(FILEINFO_MIME_TYPE);
I also save the image temporary on my ...
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How to defend vs. Image Remote File Inclusion, e.g. RFI using a .gif file (Apache/PHP)?
To defend versus Remote File Inclusion where attackers try to abuse image files, I usually recommend to never use include to include image files into PHP code.
Sometimes though, the avoidance of ...
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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 ...
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2
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1
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Arbitrary file upload, serve JPG as PHP
I'm trying out random older WordPress exploits on my local server, I'm currently in the process trying to get this one to work:
https://www.exploit-db.com/exploits/20083/
It doesn't read any headers,...
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9
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Keep encrypted files in sync on a cloud service, without having to upload an entire encrypted volume each time
Situation:
User has several folders worth of GBs which they want to keep in
sync on a cloud service (for example Mega or Dropbox) in an encrypted form;
User does not want to sync a single encrypted ...
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How does SFTP function without a manually generated public/private key pair
I am learning about SSH and how to use it to secure file transfers and commands between a windows machine and a Linux server. Everything that I have read so far indicates that I need to use an SFTP ...
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What are security risks of serving user uploaded files without Content-Disposition?
Imagine a server that serves untrusted user-provided files and allows other users to download them. Under some circumstances server can be tricked to return responses to download file requests without ...
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1
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Have I done enough not be compromised through image uploading
I know that you can never be sure that you have done enough to be secure, and I also know that file uploading is hard to make correct. Before asking this question I read some of the related posts here ...
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Is there a way to check the filetype of a file uploaded using PHP?
I don't want it to just check the extension of the file as these can easily be forged even MIME types can be forged using tools like TamperData.
So is there a better way to check file types in PHP ?
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Exploiting a PHP server with a .jpg file upload
I would like to ask a question regarding the classic uploading an image and executing php code exploit on a website.
So I have been trying out this exploit a website I'm supposed to hack (It's set up ...
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C# Image.FromStream is that secure?
after reading the data from the request as Stream i needed to convert it to Image so i used this Method:
Stream inputStream = HttpContext.Current.Request.InputStream;
Image img = Image.FromStream(...
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What does it mean to have a "file name with NULL bytes in serialized instances"?
I was browsing this page, which redirected me to this vulnerability because I'm a Java developer and I'm aware of the affected library.
Basically the vulnerability says:
It was discovered that ...
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1
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Uploading images safe of XSS, php code and virus
I know that my question has been responded lot of times, but most the responses addresses functions that I don't even use (like use include with images) and that makes me worry because maybe I'm not ...
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1
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Exploitation of missing is_uploaded_file check?
The PHP documentation for is_uploaded_file says:
Returns TRUE if the file named by filename was uploaded via HTTP POST.
This is useful to help ensure that a malicious user hasn't tried to
trick ...
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Pentesting file upload functionality
I am testing web application which allows to upload files in every format without any restrictions. There is also a function to download uploaded files but when I download file it is returned with ...
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How can nginx run a file with jpg extension as a php file?
I have a follow up question on this answer about executing image files as php. The answer explains that nginx support virtual directories. One can run
www.something.com/blan.php/one/two/3
and one/...
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votes
2
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Risks of serving untrusted content under HTTP Content-Type: text/plain?
Am I gonna run into XSS attacks by doing this, or will a file download be prompted?
Are there security problems that would rise in a modern browser?
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Will a crossdomain.xml file reduce a potential security risk?
I maintain a website were users are allowed to upload files. I'm doing already some good MIME-checks, consistency checks, virus checks, blacklist checks based on hash lists, some other custom checks ...
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MIME Type vs. Magic Numbers
I'm interested in a comparison of the two with regards to what's more secure when uploading files on a website (that I'm a programmer for).
Mozilla's page about MIME Types states that "On the Web, ...
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