An application that is accessed over a network such as the Internet or an intranet using a browser.

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22
votes
4answers
2k views

How does using OpenID affect webapp security?

Using OpenID for authenticating users grows in popularity and, in fact, makes a webapp easier to use. But what are the security considerations one should bear in mind when deciding whether to ...
22
votes
3answers
7k views

What are the best practices for hardening a php.ini file?

In order to secure a PHP installation, what are the best settings for a php.ini file? What is absolutely vital in terms of security? What is recommended for most use cases?
21
votes
3answers
4k views

What are the disadvantages of implementing HTTP authentication in a web application? [duplicate]

I know that there are different types of authentication mechanisms available. One among them is the HTTP authentication. What is the danger in using this method compared to other methods?
21
votes
9answers
3k views

Is a web application firewall necessary if the application is secure?

Recently I've been reading about Web application firewalls and the fact that they protect against most frequent attacks like injections, XSS or CSRF. However, a good application should already be ...
21
votes
5answers
5k 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?
21
votes
5answers
4k views

Should I use Suhosin for PHP?

Suhosin can be used to increase the security of your PHP application. I can really see the use of it when you are using shared hosts, with multiple (possibly evil) people running their PHP apps there. ...
21
votes
7answers
1k views

How can I protect a WordPress installation?

How do you go about protecting a default WordPress installation? What checklist do you use, best practices, tips and tricks, etc? Any recommendations on plugins, third-party tools are welcome.
21
votes
3answers
2k views

Pitfalls of using OAuth for mobile Applications

OAuth seems to be getting a lot of traction at the moment as an authorization solution for web applications and mobile applications. I'm interested in understanding what the pitfalls of using OAuth ...
20
votes
14answers
2k views

How can you become a competent web application security expert without breaking the law?

This question was asked here on Programmers Exchange, but it was suggested I ask here as well since most of the experts would likely hang out on IT Security exchange instead. I find this to be ...
20
votes
8answers
18k views

Why do people still use/recommend MD5 if it is cracked since 1996?

It's still commonly recommended way of hashing passwords, even if it's insecurity had been proven in 1996 Therefore we suggest that in the future MD5 should no longer be implemented in ...
20
votes
2answers
2k views

From a technical standpoint, how does the zero-day Internet Explorer vulnerability discovered in September 2012 work?

I'm looking for an answer that explains the issue from the prespective of a developer/engineer. What is exactly being exploited and why does it work? Please note that I am not looking for ...
20
votes
7answers
5k views

What are some good website security scanning solutions?

What are some good web-based website security scanning solutions? I'm not too concerned if they are web-based solutions, or software that can be run locally. Generally, I'm looking for something we ...
20
votes
5answers
1k views

Why do some websites and programs restrict password characteristics?

There are some websites and even programs that I use that have rediculous password restrictions. Lots of forums for instance restrict passwords to ~32 characters. Others enforce a restricted charset. ...
20
votes
2answers
749 views

How is “<scrscriptipt>” or “selselectect” used to avoid filtering?

A technique for avoid filtering of common words is the one I described in the title. However, why does this technique work? SELECT isn't the same as SELSELECTECT for example.
20
votes
8answers
1k views

How to protect against brute forcing

How do you properly implement defenses against brute forcing? Is it best to store how many times someone tried to log in and block them after X attempts? And how would "someone" be identified? With ...
20
votes
2answers
4k 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 ...
19
votes
4answers
6k views

Why users want to disable cookies?

I just started to create a new web application. In the documentation, it is written that I have to prepare for the situation where users have disabled cookies. This is not the first time I have read ...
19
votes
4answers
965 views

Should I be concerned when a “Forgot Password?” tool sends my password in plaintext?

Some sites I have been a member of in the past don't go through the normal "Forgot Password?" process. Instead of e-mailing me a unique password reset link or something of the like, I have received ...
19
votes
2answers
4k views

JavaScript Injection using Man in the Middle Attack

Suppose I am connected to a wifi-hotspot hosted by a malicious attacker. Further, suppose that I am accessing a login page of an fictitious email site tmail.com over insecure HTTP connection. My ...
19
votes
2answers
3k views

Which HTTP status codes are interesting from a security point of view?

I'm looking to extract interesting information from webserver logs and I wonder which HTTP status codes should I filter out? For example, 200 hits can be considered to be 'regular behavior' whereas ...
18
votes
6answers
3k views

Why do we ask for a user's existing password when changing their password?

In a web applications context, when a user wants to change their current password, generally they would have to enter their current password first. However at this point, the user has already been ...
18
votes
3answers
3k views

Why is it insecure to store the session ID in a cookie directly?

I am learning about session middleware. You have to supply a secret or the middleware complains: app.use(session({ secret: "abc", resave: false, saveUninitialized: false, store: new ...
18
votes
5answers
1k views

Can you secure a web app from FireSheep without using SSL?

Assume that you want to give some web users privileged access to your website, but that you are unable (or unwilling) to offer SSL to all of them - at least past the initial login page. In this ...
18
votes
4answers
18k views

How to hijack a session?

Despite the blatant title of the question, this is actually for a genuine purpose. My site uses PHP code like this: $select="select id from tableA where user_id='".$_SESSION['sess_user_id']."'"; ...
17
votes
5answers
2k views

From a security standpoint should users be asked to confirm their password when registering?

Is it advisable to have users re-type their password to confirm it's correct? On User Experience the general consensus seems to be no but I'm wondering if this has security ramifications? EDIT: my ...
17
votes
3answers
3k views

Should I have a maximum password length?

I'm creating a webapp, and part of my authentication method is password length. Should I put one in place? (say, 50 characters?) Or should I just put a minimum length (Currently at 6). Are there ...
17
votes
4answers
6k views

Is $_SERVER[ ] a safe source of data in PHP?

Can I 100% rely on $_SERVER[] to be a safe source of data that I do not need to sanitized like I do $_GET[] and $_POST[]? Thanks. OVERVIEW OF RESPONSES: So it seems there is a consensus that some ...
17
votes
4answers
7k views

Should sensitive data ever be passed in the query string?

Should sensitive data ever be passed via the query string as opposed to the postback? I realize that the query string will be encrypted, but are there other reasons to avoid passing data in the ...
17
votes
3answers
2k views

Is it a vulnerability to display exception messages in an error page?

Our web application has an error page that displays the absolute URL path and query of the page on which the error occurred, the date/time of the error, and the exception message. (We do not display ...
17
votes
2answers
725 views

What risks should I be aware of before allowing advertisements being placed on my website?

The thought of having a 3rd party send javascript, and images to end users seems to be a scary thought, but that is exactly what we are doing when I place advertisements onto my site. Does serving ...
17
votes
3answers
3k views

What is the point of the same-domain rule for xmlhttprequest when script tags/JSONP can cross domains?

I get that I don't want a page loaded from stackoverflow.com to be able to request gmail.com on my behalf and read my email--but this seems to be simply a cookie issue. Since JSONP bypasses ...
16
votes
3answers
4k views

Is encrypting SALT with given user's password more secure?

I'm learning about web security. I understand that passwords are hashed with salt. Why aren't the salts encrypted with same user's password? Cloudn't this make password cracking much harder? ...
16
votes
5answers
2k views

Is it possible to inject values in a drop down list?

Say a ASP.NET page, or any html page for that matter, has a drop down list with a bunch of prices. On posting the page, the code looks at the selection of the drop down list for a computation. Is it ...
16
votes
6answers
43k views

Testing for HTTP TRACE method

How can I test for HTTP TRACE on my web-server? I need to train a Tester how to verify that the HTTP TRACE method is disabled. Ideally I need a script to paste into Firebug to initiate a https ...
16
votes
6answers
7k views

Preventing information disclosure from browser back button/history?

I have sensitive data that will be hosted on a website, and I would like to prevent the data from being exposed in this scenario: The primary user logs off the application, but does not close the ...
16
votes
3answers
26k views

How to ensure that cookies are always sent via SSL when using ASP.NET on IIS 7.5?

Firesheep has brought the issue of insecure cookie exchanges to the forefront. How can you ensure that all cookie exchanges are forced to occur only via an SSL-secured connection to the server when ...
16
votes
3answers
5k views

Security risks with JSONP?

What are the security risks with JSONP? Is using JSONP in a new web application reasonable, from a security perspective, or is it better to use a different method for cross-origin web mashups? If ...
16
votes
4answers
5k views

Generate cryptographically strong pseudorandom numbers in Javascript?

Is there any good way to generate cryptographically strong pseudorandom (or true random) numbers in Javascript? The crucial requirement: if a.com's Javascript generates some random numbers, no one ...
16
votes
3answers
796 views

Getting a manual security code review done - What to watch out for?

We have a PHP application that we want to get code reviewed from an external security consultant, but I'm not clear on "how to" go about that process. We did specify what kind of tests he should be ...
16
votes
1answer
3k views

What is a Web Application Firewall?

What is a Web Application Firewall (WAF) and what are some of the things to look for in an effective one? Why would you deploy a WAF instead of just an IPS?
16
votes
1answer
3k views

Best way to secure javascript front end/REST back end architecture web site?

I would like to build the following project: public REST API back end which can be accessed by any authenticated client. front end with static files in HTML/CSS/Javascript with Backbone.js jQuery ...
15
votes
6answers
6k views

Is showing your IP address in the URL a bad practice?

Someone told me that showing your IP address in a URL (like hxxp://45.67.134.34/default.html) is easier to hack. Is that true? I could trace any domain name and get its IP number as well.
15
votes
6answers
3k views

Is XSS a server-side or client-side vulnerability?

My colleagues claim that XSS is a vulnerability on the server side. I always thought that this is a client side vulnerability. Which one of us is correct, and why?
15
votes
4answers
1k views

My credit union is reducing its maximum password length to 10 characters

I just received an email from my credit union saying they are redesigning their online banking service and that I will need to change my password by October 22 to conform to the new limit of 10 ...
15
votes
7answers
350 views

Is a “security measure” that doesn't provide a security benefit actually harmful?

If a security measure is implemented that doesn't provide any additional security benefit, can it be considered harmful? As an example, consider a login page where the user is asked to enter their ...
15
votes
4answers
1k views

Web Security Cheatsheet / ToDo list

Can anyone suggest a cheatsheet or ToDo list of web site and application security? A local small business owner prompted a question about web security, basically her company website just got XSS ...
15
votes
5answers
615 views

What are the most important security checks for new web applications?

I'm wondering what are the top priority security checks you should make befor launching a new webapp? I'm guessing brute force vulnerabilities and cross-site scripting. What are the other things you ...
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 ...
15
votes
4answers
12k views

Is “Why Should You Avoid AES In MySQL?” true?

From a 2012 Smashing Magazine article quite a bold statement is made to avoid AES in MySQL itself. Or as they put it "Why Should You Avoid AES In MySQL?". However, if you search for SQL encryption, ...
15
votes
3answers
3k views

Best practice in web application security authentication to avoid bruteforce attack

I want to cover the possible cases of attacking. My application already has captcha and two-factor authentication, but how can I avoid a tiny attack without annoying my users? The possible cases that ...