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

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11
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4answers
15k 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 ...
11
votes
6answers
10k views

Why are iframes allowed at all in modern browsers?

I read a number of IT security blogs (though I'm no security expert), and it seems a significant percentage of exploits in the wild are delivered through adding malicious iframes to a hacked website, ...
11
votes
6answers
3k 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 ...
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
643 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. ...
11
votes
2answers
8k 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
5answers
12k 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 ...
11
votes
3answers
3k 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 ...
11
votes
2answers
292 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 ...
11
votes
3answers
779 views

Is Gmail showing images by default a good idea for privacy?

Google have decided to show images in Gmail messages accessed via the web, iOS and Android by default: Instead of serving images directly from their original external host servers, Gmail will now ...
11
votes
3answers
955 views

How much information about the reason for an unsuccessful login should a web application give?

After an unsuccessful login attempt, should I inform the user about its reason? Or more generally, how much information about the reason for an unsuccessful login attempt should a web application ...
11
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 ...
11
votes
1answer
524 views

Public XSLT & XML playground (with PHP DOMDocument, etc.) Security Risks?

Let's say I want to set up a sandbox or playground in PHP that users can use to create (or paste in) XML and XSLT, then transform the XML via the XSLT (by means of PHP 5's DOMDocument and related ...
11
votes
1answer
2k views

How is time-based SQL injection different from other types of SQL injection?

I understand what a time-based SQL injection is, and I understand how it works (at least how it's detected/exploited). However, is there anything in specific which makes this type of injection any ...
11
votes
4answers
994 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 ...
11
votes
2answers
998 views

Security quiz for developers

Does anyone know of a short security quiz that could be administered online, to test the security knowledge of a developer? I'm looking for something simple to administer and simple to grade, ideally ...
11
votes
4answers
2k views

What is the right way of storing database connection strings from the security point of view?

What are recommendations, best practices and have-to-dos regarding handling connection strings in web applications? What things one should never, ever do?
11
votes
1answer
283 views

WAF Process Creation for Integration of IT and Business

A client has asked me to help them out with their WAF processes. Currently they have a few critical web applications being protected by a couple of WAFs. I have managed to get the WAFs tuned and ready ...
11
votes
2answers
827 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
1answer
756 views

Webapp2 security

I am coding a REST web application that runs on Google App Engine, it authenticates API requests to privileged data using sessions by cookies provided by webapp2_extras.auth and ...
10
votes
6answers
560 views

What are web attacks which users can run code on your servers?

I hear stories about insecure web servers and sites which people (or bots) break into and execute their own code on the server. My question is how is that possible? I heard of people putting their ...
10
votes
4answers
444 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 ...
10
votes
6answers
3k views

Security review: “HTTP header user-agent has been set to (something)”

We got a security review done of our PHP code and they team advised this in their report (amongst other things): /appdir/ Details The HTTP header user-agent has been set to \" . Request GET ...
10
votes
4answers
538 views

Does my UI need to be secure if my API is?

I'm working on a project that is creating two new, separate web modules (possibly even on different servers) to support a new web application, with one serving up a static JS-based UI and the other ...
10
votes
3answers
14k 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 ...
10
votes
4answers
4k views

How effective are reverse proxies as a web application security measure?

How effective are reverse proxies as a web application security device? Which types of threats do they mitigate against and which don't they? For example are they more effective in preventing ...
10
votes
3answers
371 views

What simple security considerations can I / should I make for a read-only API?

Right now I'm setting up an API, to be consumed on the client-side to set up a directory site. I'm wondering what extra steps I need to take just to prevent people from gaining write access to the ...
10
votes
3answers
432 views

Should I ask a user to re-authenticate if the browser thumbprint changes? Is a server side library available?

Is there a security benefit to using the browser's thumbprint in addition to a session identifier to identify a unique session? Would it then be advisable to ask the user to reauthenticate (or simply ...
10
votes
2answers
4k 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?
10
votes
2answers
1k views

What are the SQL-injections issues of parameterized queries?

I've written some code to generate an SQL query in ASP classic. I'm not sure if it's secure or not: Set adoCon = Server.CreateObject("ADODB.Connection") adoCon.Open "Provider=Microsoft.Jet.OLEDB.4.0; ...
10
votes
4answers
7k 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. Advantages Users ...
10
votes
4answers
339 views

What are the drawbacks of login request throttling?

In a web application, one way to protect against password guessing attacks is to lock out accounts after a set number of failed logins. This could be done on both source IP address and username. For ...
10
votes
1answer
1k views

Strict Transport Security — max_age value

I've been wondering what max-age should the HTTP Strict Transport Security header have. Both paypal and lastpass sites leave it very low: 500 (seconds = bit over 8 minutes) market.android.com has it ...
10
votes
3answers
850 views

If I am obliged to store a password/certificate on a client side, how can i make sure that it is protected?

In certain cases we need to establish a key/password/certificate as a first timer and then as a client we need to use this key/password/certificate to get authenticated. Therefore the ...
10
votes
1answer
386 views

Is there a web application firewall equivalent of virustotal?

I'm wondering if there is a web application firewall (WAF) equivalent of VirusTotal? A site where I can throw for example injection strings, exploits or xss, and it will tell me what the default ...
10
votes
2answers
2k views

How to protect against clickjacking attack but allow legit iframes?

I'm aware of modern anti-clickjacking approaches, such as X-Frame-Options header or framekiller scripts. But all these tactics prevent content to be inside iframe. But what if there is a requirement ...
10
votes
3answers
2k views

How to perform penetration testing on a Flex application?

Possible Duplicate: What tools are there to inspect Flash SWF files? I have decompiled it, verified the source. All seems fine. Appscan also is not able to find anything in this case. But I ...
10
votes
1answer
819 views

How can I embed iframe securely without restricting its functionality?

I'd want to embed an iframe from untrusted site into web application. Iframe: should be able to run Javascript and browser plugins (Flash, etc.) should not be able to access my web application ...
9
votes
3answers
1k views

How secure are sha256 + salt hashes for password storage [duplicate]

I started reading about password hashing recently on multiple sites like this page on crackstation and others, and for what I have understood, I should avoid using hashing algorithms like md5 and sha1 ...
9
votes
7answers
381 views

Aren't permanantly logged in accounts inherently insecure?

The basic premise behind a "keep me logged in until I log out" feature is a cookie is stored with some identifier that is used to log the user in again when returning to the site. While these ...
9
votes
3answers
918 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 ...
9
votes
6answers
2k 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 ...
9
votes
3answers
2k views

Is it possible to forge a post request?

Consider the following URL http://mysite.com/form?date=x. Suppose that if x is in an incorrect format, that a page is returned with <p>x is not a valid date</p>, where the page author has ...
9
votes
3answers
1k views

How do I secure my SaaS startup?

I came across this question I like to offer my startup also for security advice. Objective: building a SaaS web application that allows businesses to quickly open up online stores akin to Yahoo! ...
9
votes
4answers
309 views

What are the main security considerations that must be taken into account if you intend on creating a (localised) whistleblower website?

Also: Is it something that can be achieved with limited funds? I ask because I am intrigued by the obstacles that are in place.
9
votes
3answers
462 views

How could the string \";alert('XSS');// be used for XSS?

I was using Burp Suite for some testing and I noticed that they included the following string: \";alert('XSS');// as an attack string for an XSS payload. How could this string be used to execute ...
9
votes
4answers
23k views

Why Do we Need CAPTCHA? In what case we should use it?

In what case we should implement Captcha based security?. How accurate it is and if there exists any alternatives for Captcha based Security.
9
votes
2answers
856 views

Should user be allowed to save password in browser?

The auditing company found a bug "The Auto-complete form attribute is set in password field". They suggested to disable autocomplete for this field to prevent disclosure of it "when working on shared ...
9
votes
3answers
9k 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 ...
9
votes
3answers
4k views

Is there a way to bypass Django's XSS escaping with “unicode”?

Django (the Python web framework) escapes output to prevent XSS (Cross Site Scripting) attacks. It replaces ', ", <, >, & with their HTML safe versions. However this presentation on slide ...