Known Vulnerabilities

Written by Nathan, Edited by Taylor and Collin.


<<<<<<< HEAD There are many examples of known vulnerabilities regarding web security. Although some fixes are easy to implement with a quick Google search, others take time and effort to correct based on the programmer's individual situation. With that in mind, here are examples of known security vulnerabilities and how to combat each issue. ======= >>>>>>> e985b8a78a408333723952673f3a3ff97ac17af6

Known vulnerabilities are code creations that are known to cause unwanted and unintended effects. Because of the multitude of ways that websites can be attacked, web security is an ongoing fight between security developers and hackers. These security vulnerabilities can include a wide variety of exposures, including cross site scripting, SQL injection, insecure file uploads, authentication bypass, and many, many more. To keep things organized, the internet contains dozens of CVE (Common Vulnerabilities and Exposures) databases that are filled with examples of issues other people have found in certain websites.

Why Release the Vulnerabilities to a Database?

When the vulnerability is placed in the database, the developer isn't the only one who can make a query. Because the CVE databases are public, hackers can find the information just as easily, making the vulnerability a race between the developer and the hacker. This brings up the question: why would anyone want to create a database of known vulnerabilities? It's much easier to commit the attack than to patch a solution, test it, and push it to the server.

Fortunately, the vulnerabilities are oftentimes placed in the database by the developer after the vulnerability has been patched. This is done to tighten security on applications being actively developed by other security experts. The experts can find common issues that have been discovered by their like-minded peers, then implement the solutions into their own application. That being said, no software has been proven to be airtight, and vulnerabilities are being released every day to help combat mischievous attackers. These applications can be developed by anyone from small, upcoming businesses to software powerhouses. Below are two applications that are known to have vulnerabilities, including information on how to combat them.


Joomla! is a content management system that deals with website creation and distribution. A variety of sites have been created with Joomla, including Lipton Ice Tea, Lazarex Cancer Foundation, Michael Phelps' Store, and many more [JOO]. Because their product has been used to create millions of websites, security should be a primary concern to protect their partners and their partners' users. That being said, there is an extensive list in the Exploit Database with recent vulnerabilities with the Joomla application. Known vulnerabilities include:

SQL Injection


Joomla MSG (My Personal Messages) is a way in which users are able to communicate with one another through a website. An exploit was found that allowed for an attacker to log in as another user by appending the default message website path with SQL queries, resulting in an attacker being able to view other user's messages. Here is a link with more information regarding SQL injections. Below is an example of how the SQL injection could be implemented into a URL to access another person's messages in Joomla MSG [EDB].:

# View someone else's messages
# Reply as someone else

To protect against this, the web application should have steps in place to remove system database privileges from normal users. This will prevent an attacker from making their own queries into the database, assuming they haven't found a way to bypass the authentication of the database.

Insecure File Upload


The default Joomla Event Manager (JEM) allows for an authenticated user to upload HTML and HTM files as an attachment. If an attacker was to upload the files containing malicious Javascript coding, a victim would be able to download said files. This would put them at risk to whatever hack the attacker created. More information on insecure file upload can be found here. In order to prevent this type of vulnerability, the JEM should restrict file uploads to valid files of a certain type.


Apple is a large, multibillion-dollar company that offers a variety of services. One of these services includes Apple WebKit, a web browser engine used by OS X applications including Safari [AWK]. Developers can use Apple WebKit to create their own web browsers. There are several past vulnerabilities found with Apple WebKit, including the following:

Cross Site Scripting


Cross Site Scripting (or XSS) is a vulnerability that is usually found within web applications. An attacker using XSS can inject their script to a normal website, which unknowingly passes the malicious script to the user [XSS]. The script language is usually Javascript due to nearly every website using some form of it. The script can then read the information that the user's computer transmits to the website, including location and cookies. A further description of XSS can be found here.

Apple's WebKit engine (specifically on Safari 10.0.2) is vulnerable to this type of attack. The code attacks the FrameLoader::clear function that clears the user's screen. XSS is then injected into the unload event handler with Javascript to execute whatever function the attacker desires. The code looks similar to this [EDB].:

function main() {
    let f = document.body.appendChild(document.createElement("iframe"));

    let a = f.contentDocument.documentElement.appendChild(document.createElement("iframe"));
    a.contentWindow.onunload = () => {
        let b = f.contentDocument.documentElement.appendChild(document.createElement("iframe"));
        b.contentWindow.onunload = () => {
            f.src = "javascript:''";

            let c = f.contentDocument.documentElement.appendChild(document.createElement("iframe"));
            c.contentWindow.onunload = () => {
                f.src = "javascript:''";

                let d = f.contentDocument.appendChild(document.createElement("iframe"));
                d.contentWindow.onunload = () => {
                    f.src = "javascript:setTimeout(eval(atob('" + btoa("(" +function () {
                    } + ")") + "')), 0);";

    f.src = "";


Use After Free

Use after free is an issue that targets memory corruption, attempting to access memory after it has been freed by the RAM. This attack can cause the application, or web browser, to crash. In more serious instances, this vulnerability can lead to the attacker remotely executing code on the user's computer [UAF]. This vulnerability was found in regards to Apple's WebKit in the HTMLFormElement::reset() function. There was a flaw in how the software accessed the associated elements variable, allowing it to be modified by the reset function. By adding custom elements to the variable while it is iterated, the already-existing elements are pushed forward, letting the attacker execute his or her own data [EDB].

Prevention of Known Vulnerabilities

In order to protect your web projects, there are plenty of companies that perform security tests that spot weak points in your code. They can pull from CVE databases in order to attack your code in every which way, letting you know exactly how attackers will attempt to breach your security. Utilizing their services, as well as performing security tests of your own, is paramount in creating a safer, more secure internet. There are also update options offered by many CVE database sites, notifying you of any recent breaches in applications like yours. Therefore, using these databases and checking for past security exploits is the best way to prevent attackers from manipulating your website via known vulnerabilities.

Works Cited

[JOO]"" Joomla! N.p., n.d. Web. 24 Feb. 2017.
[EDB](1, 2, 3) "Offensive Security’s Exploit Database Archive." Exploits Database by Offensive Security. N.p., n.d. Web. 24 Feb. 2017.
[UAF]Stroud, Forrest. "Use After Free." What Is Use After Free? Webopedia Definition. N.p., n.d. Web. 26 Feb. 2017."
[AWK]"WebKit." WebKit. N.p., n.d. Web. 24 Feb. 2017.
[XSS]"What Is Cross-site Scripting and How Can You Fix It?" Acunetix. N.p., n.d. Web. 25 Feb. 2017.