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

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13
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5answers
3k views

Solution to allow JavaScript input but prevent XSS

We have a simple Blog system that allows users to input html and JavaScript to build a blog page. I'm aware that allowing javascript open up the door to xss attacks. We do however need to allow users ...
13
votes
6answers
3k views

Filter user input before the database or upon display?

Given a web application where user data must be properly escaped to avoid XSS, is it better to try to remove the "bad stuff" before it enters the database, or is it best to allow it in the database ...
13
votes
4answers
750 views

Custom socket server on the internet running as root

We are writing a custom socket server which runs on a high port. Until recently, it has been running behind a corporate firewall. Now, it has been decided that the server should be taken outside the ...
13
votes
7answers
4k views

Should we force user to HTTPS on website?

Should we force website from HTTP to HTTPS , one of the method is using .htaccess: RewriteCond %{SERVER_PORT} 80 RewriteRule ^(.*)$ https://www.example.com/$1 [R,L] But what I notice is that some ...
13
votes
2answers
9k views

What is the benefit of the scope in OAuth2?

In the question, substitute scope with state. Since there is an answer based on the wrong question, I'll let everything below as is. The answer is useful nonetheless. This question refers to ...
13
votes
4answers
12k views

What SSL key should I make for IIS: RSA or DH? What bit length is appropriate?

I'm creating an SSL cert for my IIS server and need to know when I should choose the Microsoft RSA SChannel Cryptographic Provider or the Microsoft DH SChannel Cryptographic Provider. Question 1 Why ...
13
votes
3answers
389 views

Malicious QR Code and Mitigation

I just started reading a little on QR code, so I'm not entirely familiar with QR Code capabilities, but a thought crossed my mind today. I scanned a QR Code on a postcard I received, and it ...
13
votes
6answers
10k views

Disable insecure/dangerous PHP functions

Typically my job description limits me to code-review of web applications. More recently I've been asked to assist with some server-side PHP optimization where, although I am familiar with it, I lack ...
13
votes
1answer
5k views

enable browser caching with HTTPS

I understand that sensitive data should not be cached (ie, you dont want to cache an HTML file with all of your bank account details in it), but there are some things that HTTPS protected sites should ...
13
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3answers
1k views

Elaborate websockets security

I'm interested in learning more about web sockets security. Read that web sockets were originally in Firefox, removed for security reasons and now added back in with the problem resolved: ...
13
votes
2answers
232 views

Would suggesting a random passphrase during sign-up hurt overall security?

I've been looking for ways to improve security and security awareness for both internal and external clients and I happened upon the idea of generating a one-time, random "password suggestion" on the ...
13
votes
3answers
3k views

ASP.NET MVC security check list

I am planning to start a new web site on ASP.NET MVC 2 (3). Does anybody a full (if possible) check list of actions, approaches I should reach to avoid almost problems with security?
13
votes
3answers
1k views

What does a HTML filter need to do, to protect against SVG attacks?

I recently learned that SVG (Scalable Vector Graphics) images introduce a number of opportunities for subtle attacks on the web. (See paper below.) While SVG images may look like an image, the file ...
13
votes
6answers
2k views

Securely building a local pentest lab in a VM

I'd like to set up OWASP WebGoat or a similar vulnerable web app in a VM (probably VirtualBox on Linux). For convenience's sake, I'd like to get it running on one of the primary machines I use (say, a ...
12
votes
7answers
2k views

Whitelisting DOM elements to defeat XSS

As we know, developers are responsible for correctly escaping/validating data provided by the user before rendering or storing them. However, we must agree that it's relatively easy to forget a single ...
12
votes
5answers
7k views

What is a DoS Attack and how does it differ from a DDoS attack?

Can some one explain to me the concept of Dos Attacks for web applications ? Also what is the distinction between Dos and Distributed Dos ( ie DDos) attacks ? Wikipedia says : In computing, a ...
12
votes
4answers
3k views

Preventing reverse-engineering of client application

I have a web service which is used by a Flash client. Both the service and the Flash client is produced by me (read: my company). The Flash client communicates with the server over HTTPS. One of the ...
12
votes
6answers
1k views

Where to start with security testing?

Starting with a QA team that deals mainly with functional requirements testing and has little real security testing experience, what simple practical things should the QA team start doing to start ...
12
votes
4answers
358 views

Sensitive information was placed in a publicly accessible folder. Who is responsible and how to proceed?

Background We have an IT staff who manages our server and a web developer who is not on the IT staff and has no root access to the server. All involved do very high quality work and I do not consider ...
12
votes
8answers
2k views

Facebook account keeps getting hacked, can't seem to figure out why or how?

One of my friends, she has a lot of friends on Facebook, and uses it for marketing. Her account keeps getting broken into. Her password gets reset and/or gets locked for changing resetting password ...
12
votes
4answers
22k views

How to know which database is behind a web application?

I've read that different databases (mysql, sql server,...) have different vulnerabilities and that they are vulnerable to some specific sql injections. When attacker try to perform a database attack ...
12
votes
6answers
4k views

Is there a security risk running web apps in debug=“true”?

This is a copy of the original question on Stack Overflow which didn't get much love and is probably more relevant here: There are plenty of performance reasons why apps shouldn't be run in ...
12
votes
5answers
2k views

Unknown process on my ubuntu machine communicating over multiple ports with UDP proto

I have a Django web application where the web app and the postgresql database are hosted on two separate Ubuntu-based machines. On my Database machine (and not my web application), if I run sudo ...
12
votes
3answers
22k views

Is it possible to execute a php script in an image file? [duplicate]

I have an image upload php website. Users can upload images to my website. A user claims he can hack my website using an uploaded image. I opened all the images that he uploaded to my server with ...
12
votes
3answers
731 views

Is stripping out < and > characters an effective way of preventing XSS?

I'm guessing that HTML encoding the input would probably be a better solution, but I'm curious if just stripping out any < and > characters would be an effective defense against XSS attacks. ...
12
votes
4answers
4k views

Challenging challenge: client-side password hashing and server-side password verification

We have a website where users need to log in to access privileged information. Obviously we are using SSL, but I also want to avoid plaintext passwords from accidently ending up in server logs, or ...
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 ...
12
votes
4answers
763 views

How should I secure a contact form that appears on every page of a website?

My client has a small "Contact Us" form on every page of their website. They are adamant about not including CAPTCHA verification on these forms, to keep them easy to use, but I feel it is my ...
12
votes
4answers
747 views

What does defense in depth entail for a web app?

I'm assuming it means different layers of security from app-level security to server hardening to personnel training, but what are each of those layers and what are some good resources for each level ...
12
votes
5answers
15k views

Benefits of identifying clients based upon the “X-Forwarded-For” or similar HTTP header in addition to Client IP

The X-Forwarded-For header is used by some HTTP proxies to identify the IP address of the client. The wiki page (linked above) mentions that ISPs may use this header as well. In addition there are a ...
12
votes
2answers
319 views

Preventing Voter Fraud on a Social Media Contest

I'm creating a contest that will allow users to login using their Facebook & Twitter accounts and submit votes on videos. My clients concern is that users will game the system by logging into ...
12
votes
4answers
2k views

Sending HTTP 403 as. 200 - “Silent Identification of Admin”

A researcher recently reported an issue in a site about using script on a 3rd party site to discover if a user is an admin. Here's the scenario: Main site is target.example Attacker site is ...
12
votes
2answers
1k views

Interpolique: transparently preventing SQL Injection and XSS with base64 encoding, what happened?

For the keynote at The Next HOPE a couple of years ago, Dan Kaminsky unveiled Interpolique (the talk is really fun btw). The problem he raised was how to defend against injection attacks, including ...
12
votes
4answers
10k views

What are the disadvantages of single sign-on authentication?

We were discussing to implement single on in our web application,right now after analyzing we came to know that the following were the advantages of single sign on authentication. In the words of ...
12
votes
2answers
1k views

Is request signing (digesting the request body) in a REST API necessary?

I am currently engaged in a debate and I wondered what the community's opinion on this was. We see REST APIs which just require basic authentication (perhaps HTTP) or OAuth. We see REST APIs which ...
11
votes
4answers
3k views

Authenticating without a database

I've been inspired by a question over on Code Review, which boils down to: What is the proper way to authenticate a user without a database? Would it be the exact same process if you stored ...
11
votes
3answers
3k views

Is it dangerous to show all the JavaScript functions in my web application? [duplicate]

Right now I'm developing a web application and it uses a lot of JavaScript functions so I'm putting all of them in different JS files to access from the HTML, but the functions are "easy readable" so ...
11
votes
7answers
4k views

How does CAPTCHA mitigate DDoS attacks?

This seems like an easy question, but I've failed to find an answer. One of the uses of CAPTCHA is to cope mitigate Denial of Service attacks. Suppose an adversary performs excessive login attempts, ...
11
votes
4answers
1k views

Why should I use whitelist on a WAF?

I was studying different WAFs, from open-source (such as ModSecurity and NAXSI) to commercial solutions (Imperva, Citrix, Fortinet, etc.). Many people state that having a whitelist-based WAF is far ...
11
votes
2answers
3k views

What does this injected code do?

One of my sites has just been hacked as this code has been inserted into random(?) files and places within the files. Does anyone understand what it is trying to do? I would welcome anything that may ...
11
votes
4answers
576 views

Should a web application return true http errors?

Exception and error information can be used by a malicious user to map out the API of an web application, so it is routine to see security checklists to advise returning only a "Please contact your ...
11
votes
3answers
5k views

Must login and logout action have CSRF protection?

I am making a web application in Django which generates and includes CSRF tokens for sessions (a Django session can be anonymous or a registered user). Should I keep CSRF protection to the controllers ...
11
votes
6answers
2k views

Ads appearing in our application when they should not be

I received a strange issue reported by one of my web application users. Apparently they are getting "ads" within the browser window when using my application. I didn't add advertisements at all. It's ...
11
votes
7answers
2k views

IP address black list

My website has a black list of IP addresses. The web application, in some way, detects all invalid, suspicious influences to it and remembers IP address and denies any requests from that IP address. ...
11
votes
3answers
1k views

What security measures should be taken when running a Linux web server out of our office?

I am interested in running our company's web server from our local office. The office makes use of file sharing and NAS devices among other common office protocols. The worst case scenarios I've ...
11
votes
2answers
11k views

Implications of Trace/Track Methods on Apache

When performing vulnerability scans using Nessus, against a host running Apache, one expected result is always "HTTP TRACE / TRACK Methods Allowed". While this result only has a base CVSS of 4.3, I ...
11
votes
4answers
2k views

How dangerous is it to store password in plain text on sites like GitHub?

I have a few private repositories set up on GitHub for some of the projects I am working on for my company. These applications connect to databases and I have database authentication credentials ...
11
votes
2answers
8k views

Why is it so hard to close onion domains (e.g. The Silkroad)?

A few months ago when I started to experiment with bitcoin I came across The Silkroad (only accessible via Tor) For those who do not know what Tor is and who do not want to waste their time ...
11
votes
2answers
771 views

Is allowing unfiltered curl request from a website a vulnerability?

Recently I was on a website which provided some non-sense feature: Enter a URL Press enter HTML source of a given URL is displayed It basically fetched a URL and just dumped the contents of it. ...
11
votes
2answers
6k views

What can an attacker do with a stolen SSL private key? What should the web admin do?

What can an attacker do with a stolen website certificate and key? What should the website admin do upon learning this?