Famous xss attacks

So here are the 7 cases everyone should know to be able to exploit the vast majority of XSS flaws out there. A web page to show them with their variations single or double quotes was built to training click to go to it :. As you might notice, all cases are source-based which means that injection always appears in source code retrieved in the body of an HTTP response. Independent of being of reflected or stored type, important here is the context where they appear when DISPLAYED so we will always use the reflected one as main example.

The most straightforward one, input is reflected just right in the code between existing tags, after or before them. Which closes the value and gives room to insertion of the onmouseover event handler. Input sometimes land into a javascript block script tagsusually in the value of some variable of the code. So the way to go is to inject javascript code, respecting the syntax. For that, we have a little trick: escaping the escape. We insert a leading backslash to escape the added one and then the quote will work to break.

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Hackers still exploiting eBay's stored XSS vulnerabilities in 2017

Tested Proof-of-Concept vectors and payloads. Covers basics to advanced, filter bypass and other cases. Clear directions for dozens of different scenarios.Fraudsters are still exploiting eBay's persistent cross-site scripting vulnerabilities to steal account credentials, years after a series of similar attacks took place. Worse still, many of the listings that exploited these vulnerabilities remained on eBay's website for more than a month before they were eventually removed.

All of the attacks stem from the fact that eBay allowed fraudsters to include malicious JavaScript in auction descriptions. Previous attacks exploited this vulnerability to place malicious redirect code on high-value vehicle listings, with the intention of stealing login credentials from other eBay members, whose accounts could then be used to list even more fraudulent vehicle listings.

But fraudsters are now using malicious scripts on a wide variety of lower-value items, including legitimate listings that had already been posted from reputable eBay accounts. Fraudsters have seemingly compromised these accounts and appended additional information to many of the members' existing listings — and this is where the malicious JavaScript is placed. As can be seen below, the cybercriminals even used listings of dental tools to extract credentials from their victims, bypassing eBay's toothless listing policies in a similar way to the attacks that took place a few years ago.

Clicking on the above listing took the user to the following page, which included malicious JavaScript that had been injected by the fraudster:. But the malicious code in this listing executes as soon as the page has loaded, which causes it to be displayed for only a split second.

In the blink of an eye — and without any further interaction — the victim is redirected to a spoofed login form:. Victims are unlikely to expect a phishing form to appear as a result of clicking on an eBay search result, and so the efficacy of these attacks is likely to be far greater than the average phishing scam.

Allowing listings to include arbitrary JavaScript not only facilitates this type of fraud, but also allows fraudsters to capitalize on the trust instilled by the eBay website. In this particular example, the malicious code injected by the attacker was obfuscated to make its purpose less apparent — possibly to get around any text-based content filters implemented by eBay.

The obfuscated script is used to load a much larger JavaScript payload from an external location at user The externally-hosted script redirected victims to a data URI, which is another trick sometimes used by cybercriminals: The Baseencoded address makes it difficult for victims to report such attacks, as by this point, the page is ostensibly not hosted anywhere. When the victim submits his username and password, the credentials are transmitted to a script at daviddouglas.

This PHP script receives the victim's credentials and then immediately redirects the victim to a page on the genuine eBay website, giving the impression that the listing that the victim originally attempted to visit is no longer available:. The victim may not realise it — as his browser never showed the address of any externally hosted websites — but at this point, his credentials will have already been stolen by the fraudster's PHP script.

The fraudsters behind these attacks can attempt to monetize these stolen credentials by selling them to other fraudsters, or use them to propagate malicious code into even more listings. In the dental tool example, malicious JavaScript was added to the listing on 8 Decemberand remained there until late Januarygiving the fraudster more than a month and a half to exploit the vulnerability.

The compromised seller account involved in the above attack had over a thousand of its listings infected with malicious JavaScript, many of which flew under eBay's radar for more than a month, despite having obvious malicious intentions. The only deterrent is eBay's JavaScript policywhich disallows the use of JavaScript redirects — but this is evidently not entirely effective, as it failed to prevent it being exploited for extended periods, and fraudsters will obviously not care about breaking policies that are not proactively enforced.

These latest listings were reported to Netcraft by "Jaco Bustero". Although this pseudonym is very similar to "Buster Jack" — who discovered a series of related scams in — they are, in fact, different people in the UK. Both hide behind pseudonyms because of valid concerns about their own safety — for instance, Buster Jack's efforts to combat vehicle fraud have earned him several death threats from the perpetrators of these crimes. But fortunately, the end of script-based attacks may soon be in sight on eBay.

In an effort to make its listings mobile-friendlyeBay plans to limit the use of active content such as JavaScript at some point inbefore eventually blocking it altogether. If this is implemented as a technical control for example, by using iframes with Content Security Policy and sandbox restrictionsthen such attacks should become impossible to carry out against modern browsers.

The most recent attacks have taken place over the past 12 months, after eBay had responded to ' previous reports ' of JavaScript-based attacks, when it claimed not to have found any fraudulent activity stemming from these cross-site scripting vulnerabilities.

In some cases, it could be that eBay is simply unaware of the fraud it is facilitating.We recently migrated our community to a new web platform and regretably the content for this page needed to be programmatically ported from its previous wiki page.

famous xss attacks

Cross-Site Scripting XSS attacks are a type of injection, in which malicious scripts are injected into otherwise benign and trusted websites.

XSS attacks occur when an attacker uses a web application to send malicious code, generally in the form of a browser side script, to a different end user. Flaws that allow these attacks to succeed are quite widespread and occur anywhere a web application uses input from a user within the output it generates without validating or encoding it.

An attacker can use XSS to send a malicious script to an unsuspecting user. Because it thinks the script came from a trusted source, the malicious script can access any cookies, session tokens, or other sensitive information retained by the browser and used with that site. These scripts can even rewrite the content of the HTML page. The malicious content sent to the web browser often takes the form of a segment of JavaScript, but may also include HTML, Flash, or any other type of code that the browser may execute.

XSS attacks can generally be categorized into two categories: stored and reflected. Stored attacks are those where the injected script is permanently stored on the target servers, such as in a database, in a message forum, visitor log, comment field, etc.

The victim then retrieves the malicious script from the server when it requests the stored information. Reflected attacks are those where the injected script is reflected off the web server, such as in an error message, search result, or any other response that includes some or all of the input sent to the server as part of the request.

famous xss attacks

Reflected attacks are delivered to victims via another route, such as in an e-mail message, or on some other website. Reflected XSS and Server vs. The difference is in how the payload arrives at the server. XSS can cause a variety of problems for the end user that range in severity from an annoyance to complete account compromise.

Other damaging attacks include the disclosure of end user files, installation of Trojan horse programs, redirect the user to some other page or site, or modify presentation of content. An XSS vulnerability on a pharmaceutical site could allow an attacker to modify dosage information resulting in an overdose. XSS flaws can be difficult to identify and remove from a web application. The best way to find flaws is to perform a security review of the code and search for all places where input from an HTTP request could possibly make its way into the HTML output.

Nessus, Nikto, and some other available tools can help scan a website for these flaws, but can only scratch the surface. If one part of a website is vulnerable, there is a high likelihood that there are other problems as well. An attacker can steal cookie data via Javascript even when document. If we need to hide against web application filters we may try to encode string characters, e. We may encode our script in base64 and place it in META tag. This way we get rid of alert totally.

More information about this method can be found in RFC Cross-site scripting attacks may occur anywhere that possibly malicious users are allowed to post unregulated material to a trusted website for the consumption of other valid users.

The most common example can be found in bulletin-board websites which provide web based mailing list-style functionality.

The code in this example operates correctly if eid contains only standard alphanumeric text. If eid has a value that includes meta-characters or source code, then the code will be executed by the web browser as it displays the HTTP response. Initially, this might not appear to be much of a vulnerability. After all, why would someone enter a URL that causes malicious code to run on their own computer? The real danger is that an attacker will create the malicious URL, then use e-mail or social engineering tricks to lure victims into visiting a link to the URL.

When victims click the link, they unwittingly reflect the malicious content through the vulnerable web application back to their own computers. This mechanism of exploiting vulnerable web applications is known as Reflected XSS.Some of the more darker aspects of the web can be said to revolve around something called a denial of service attack. Cyber attacks like these only come out of the deep web, or other wise known as the dark web. Or do they? I will be covering some pretty famous DDoS attacks.

If you are new to the cyberdefense field and are looking to learn more, you might be wondering what a DDoS attack is? As I stated earlier in the opening paragraph of this article, DDoS is short for a denial of service attack. As the name implies, it is denying someone, or something a type of service.

These hackers that deploy a DDoS attack are attempting to prevent the internet server from giving service to your website. You as a user will not be able to access a website where ever it is being hosted. How are they able to accomplish? Let me explain. Hackers get hundreds if not thousands of internet users to download a specialized software with the intent of utilizing a denial of service attack. The users who download this type of software may know that they are downloading it with a full intent on being apart of a denial of service attack.

However, users may download this DDoS software with malicious purposes without even knowing that their computer will be a part of a denial of service attack. They could download the virus unintentionally through a phishing attempt. Denial of service attacks work like this especially famous DDoS attacks. Since a bunch of users have this malicious software downloaded onto their computer whether they know it or not, a hacker will then target a specific website to attack.

What ever, you get the point!

3 Famous DDoS Attacks

Just know that this is a website being targeted for an attack, and it is being hosted on a server somewhere. The hacker can now execute his attack by having all of the users with the downloaded denial of service attack software on their computers attack the targeted websites. These hundreds if not thousands of computers will send multiple request a few thousands times all together within milliseconds flooding the server that the website is being hosted on.

Through all these requests, the server will then become overloaded and have no choice but to shut down. The server shutting down will of course force the website to no longer be on the web.

This will tell the hosted website that you have been hacked! I mean they are just online websites shutting down temporarily right?

Famous DDoS attacks have caused a lot of damage to many peoples lives. Lets say the only income you receive is on running a blog that deals with a topic of taking information security classesor maybe you even have an eCommerce website that sells products online as your financial life source, or what if you are a government agency providing valuable real time information to the public on lets say the Zika virus.

Denial of service attacks are extremely harmful. They are harmful because they are preventing the sites owner from doing business as. If a website shuts down for even a few minutes, that can be a detrimental loss of revenue, especially for small and large business owners alike. As you can see, denial of service attacks are a major threat in the cyber security field. Before we cover our most famous DDoS attacks, Let us talk about the different types of denial of service attacks.

There are some different types of DDoS attacks that I will be briefly touching up on.As a penetration tester, you want your customers to understand the risk of the vulnerabilities that you find. And the best way to do this is by creating a high-impact proof-of-concept POC in which you show how attackers can exploit the vulnerabilities and affect the business.

Cross-Site Scripting XSS is a vulnerability in web applications and also the name of a client-side attack in which the attacker injects and runs a malicious script into a legitimate web page. For demo purposes, we will use the well-known DVWA applicationwhich we have installed locally. Most web applications maintain user sessions in order to identify the user across multiple HTTP requests.

Sessions are identified by session cookies.

famous xss attacks

For example, after a successful login to an application, the server will send you a session cookie by the Set-Cookie header. Now, if you want to access any page in the application or submit a form, the cookie which is now stored in the browser will also be included in all the requests sent to the server.

This way, the server will know who you are. Thus, session cookies are sensitive information which, if compromised, may allow an attacker to impersonate the legitimate user and gain access to his existing web session. This attack is called session hijacking. JavaScript code running in the browser can access the session cookies when they lack the flag HTTPOnly by calling document. So, if we inject the following payload into our name parameter, the vulnerable page will show the current cookie value in an alert box:.

Now, in order to steal the cookieswe have to provide a payload which will send the cookie value to the attacker-controlled website. As a result, the browser will make an HTTP request to this external website So here is the attack URL which will send the cookies to our server:. When the browser receives this request, it executes the JavaScript payload, which makes a new request to If we listen for an incoming connection on the attacker-controlled server The same information can be found in the access.

With the above cookie information, if we access any internal page of the application and append the cookie value in the request, we can access the page on behalf of the victim, in its own session without knowing the username and password.

It can be set when initializing the cookie value via Set-Cookie header. However, using the XSS attack, we can still perform unauthorized actions inside the application on behalf of the user.Has the XSS threat died down? But recent data paints a different story:. Compared to the dramatic stories of huge data breaches, XSS attacks appear to have a much smaller impact.

XSS - Cross Site Scripting Explained

For instance, an attacker may post a comment that includes a malicious script on an article through an XSS vulnerability. The attacker needs to trick the user into clicking a malicious link for instance through a phishing email or malicious JS on another pagewhich triggers the XSS attack.

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Privacy Policy. Beforethe Akamai report did not state the number of XSS attacks, making it difficult to extend this timeline backward. Imperva reports that in the yearsandthe average web application in their data set was attacked by XSS 8, 12, and 21 times respectively.

The 7 Main XSS Cases Everyone Should Know

Looking at the gross number of XSS vulns, the past few years exhibit an uneven trend. However in there is a dramatic upward trend —in the first 5. We should note that this data does not include DOM-based XSS attacks, which occur on the client side and are next-to-impossible to detect.

In our experience, these types of attacks are growing in prevalence as single page apps become more popular and websites provide richer client-side functionality. Many of those vulnerabilities are XSS, which would be difficult to detect by traditional monitoring tools. Many may have been exploited by attackers data which was not available to us at the time of this writing. The metric was XSS as a percentage of all vulnerabilities found on participating websites.

This data counters the argument that XSS is diminishing or disappearing. Consistently, XSS is one of the top 3 vulnerabilities detected on websites, with a big gap in the prevalence percentage between the top 3 and the rest of the vulns. The EdgeScan Vulnerability Statistics Report supports this data with very similar numbers gathered with a similar methodology.

The data show that XSS is still a very big deal, and is probably entering the next wave in terms of prevalence of vulnerabilities and number of attacks:. As a result, one remote and rarely used page, which uses old JavaScript and is susceptible to DOM-based XSS, exposes and endangers all user data and actions for the domain it is hosted on.

At Snykwe protect thousands of web apps from XSS and other vulnerabilities, found in the open source packages they use. Based on our experience, we can suggest five reasons why XSS is not going away as many experts hoped and why it might become a more difficult security problem in Increasingly important data is transferred and actions taken via the web—making XSS attacks much more compelling for attackers to exploit.

Single Page Apps increase the amount of client side logic and user input processing. This makes them more likely to be vulnerable to DOM-based XSS, which, as previously mentioned, is very difficult for website owners to detect. Mobile screens hide browser informationfor instance by truncating URLs and query strings, making it harder for users to spot something unusual when surfing via their mobile. Increased use of open source librariesused by most websites and further encouraged by frameworks such as React and Angular, multiplies the reach of an XSS vulnerability in such libraries.

Application developers, website owners, and security officers should all take note—XSS attacks are a big red flag in and deserve careful attention.

More than ever, applications should be developed, tested, scanned and updated with XSS flaws in mind, to reduce organizational risks and harm caused to customers and users. June 8, in Vulnerabilities. By Guy Podjarny. But recent data paints a different story: 1.

Test your applications for vulnerabilities By submitting this form you consent to us emailing you occasionally about our products and services.Cross-site scripting is one of the most common OWASP vulnerabilities, affecting both small businesses and large corporations.

OWASP is a non-profit organization with the goal of improving the security of software and the internet. A proof of concept video is found at the end of the article. The exploitation of a XSS flaw enables the attacker to inject client-side scripts into web pages viewed by users. It is often assumed that cross-site scripting means JavaScript, but could also include e. Cross-site scripting is often said to be the most common vulnerability, and many sites are affected.

This includes small local sites as well as giants like Google. InCross-site scripting was among the top 5 most common critical vulnerabilities discovered by the Detectify scanner. Any source of data that the browser ends up rendering is a potential attack vector.

Cross Site Scripting (XSS)

This means there are many different potential ways to exploit the site, and the risk therefore increases. Cross-site scripting is considered one the easier to understand vulnerability types. With that said, there is no limits on how to complicated it can be to exploit under different circumstances and protections. One of the most famous attacks is the attack called Samy. Within 20 hours, over a million users had fallen victim for the vulnerability. Another well-known attack, similar to Samy, is the only two years old attack on TweetDeck.

This means it quickly turned into a worm that spread itself. At first, it is easy to think about only the normal places, but after a while it is obvious that there are many more vectors than one would initially think about.

Then there is reflected cross-site scripting, which is when page simply reflected some kind of input from the user. However, there are also stored cross-site scripting vulnerabilities, where the server instead echoes something stored in the database.

This makes it hard to automatically analyze everything, as an attacker would benefit from being able to reverse track every output to see where the data comes from and how it has been manipulated on its way there.

In short, it can be concluded that for discovering the first mentioned type the site owner would need to follow the dataflow all through JavaScript to see how it treats user input. In this case, user input can be default variables in JavaScript such as. In real life examples, it is not uncommon to see a combination of these vulnerability types. Detectify is a web security scanner that performs fully automated tests to identify security issues on your website. It tests your website for over vulnerabilities, including cross-site scripting and other OWASP Top 10 vulnerabilities, and can be used on both staging and production environments.

This would output the user input straight to the HTML-document. As such, if a user would give HTML as input the browser would be required to render that.


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