Foojay Today

How Social Trends Help Me Fix Essential Vulnerabilities

November 04, 2021

Recently, Snyk added social trends to its vulnerability data. This new indicator shows you what vulnerabilities are trending so you can better prioritize remediation. Our research team found a strong correlation between socially trending vulnerabilities and the existence of exploits that can actually harm your application. 

Following the social trends of security vulnerabilities makes practical sense. When a specific vulnerability is gaining a lot of interest in social — Twitter, for instance — it means a lot of people are aware of the problem. Statistically, this also means more people that want to do you harm. Therefore, it can be important to put some extra focus on the vulnerabilities in your system that are socially trending.

Let’s take a look at vulnerability social trends (sentiment analysis) in action.

A trending example in Java

I created a small Java application based on an outdated Spring Boot version, 2.2.0-RELEASE. After connecting the GitHub repo to my Snyk account, I found the following vulnerability on top of my list because it is currently trending on social media. 

It is a remote code execution (RCE) vulnerability in the embedded Apache Tomcat version that ships with the specific Spring Boot starter package I use. By clicking on the trending button, I found many tweets referring to this specific vulnerability and a working exploit that is published. I will come back to this later, but first, let me explain the vulnerability.

Remote Code Execution Vulnerability CVE-2020-9484 explained

I will briefly explain the dynamics of this RCE vulnerability in Tomcat. This vulnerability exists in all Tomcat versions, including the embedded version supplied with Spring Boot. It is also good to know that a new update is already available for all versions fixing this issue.

Suppose you are using the PersistentManager with a FileStore in Tomcat. The PersistentManager manages the session. A session is used to preserve state between the client requests to the server. By default, Tomcat uses the StandardManager that keeps the sessions in memory. However, the PersistenManager swaps out sessions to storage, if they are idle for some seconds. This can be a disk using the FileStore or a database using the JDBCStore.

Using the FileStore, Tomcat stores in a predefined location as <JSESSIONID>.session. If the new call with a session ID is not in memory, the PersistentManager will look at the stored sessions on disk and deserializes the stored session object into memory when found. 

But what if my session is something this JSESSIONID=../../../../../../../foo/mysession? Because of the path traversal, Tomcat will look for mysession.session in the foo directory. If I am able to upload a file to this system for some reason, I can upload a serialized session file. Next, I can trigger deserialization by setting my JSESSIONID to the corresponding location. Deserialization triggers harmful remote code execution depending on the serialized object.

If you want to know more about why deserialization vulnerabilities are harmful, please read the blog post Serialization and deserialization in Java: explaining the Java deserialize vulnerability.

For more information about this vulnerability in Tomcat, a great article on redtimmy.com explains it in more detail. You can find an exploit proof of concept on this GitHub repository:  https://github.com/masahiro331/CVE-2020-9484

How Snyk Social Trends help you focus on the important stuff

You might say that this vulnerability has a bunch of prerequisites before it can actually be exploited. 

  1. PersistentManager needs be enabled using the FileStore
  2. Attackers need to be able to upload an arbitrary file
  3. There needs to be a gadget available on the classpath for the deserialization attack

Some people might say, because of these prerequisites not many cases are actually exploitable and dismiss it. However, because of the large amount of attention on Twitter, I took a good look and saw that it was not that hard to change the session manager to the PersistentManger with FileStore. Also with the amount of dependencies I am using in my application the change of having a gadget in there is quite possible.

So, if for some reason someone in my team decides to use the PersistentManger with FileStore the only thing missing is arbitrary file uploads. Given the fact that security breaches are almost always a chain of events that lead to a disaster — and not just a single event or vuln — I don’t think you can just dismiss a vuln like this. Especially not if fixes are available.

More importantly, if a vuln is trending, this means a lot of people know and talk about it — including people with bad intentions. For me, it is a marker that I have to investigate such a vuln even more closely than I already do to see if I am vulnerable now or will be in the future. 

Including the trending marker in the Snyk UI not only puts a spotlight on the vuln but also increases the priority score for that reason. Therefore, we believe that searching social media to determine the popularity of a specific vulnerability is a powerful tool so I will not get caught by obvious and well-known security mistakes. So when you see , we encourage you to take a second look at a vuln you may have ignored before.



This article was originally posted on the Snyk.io blog: https://snyk.io/blog/snyk-social-trends-fix-security-vulnerabilities/ and is used with permission.

Related Articles

View All
  • Avoid Java Serialization!

    Serialization in Java allows us to transform an object to a byte stream. This byte stream is either saved to disk or transported to another system. The other way around, a byte stream can be deserialized and allows us to recreate the original object.

    If you need to Deserialize an inputstream yourself, you should use an ObjectsInputStream with restrictions. A nice example of this is the ValidatingObjectInputStream from Apache Commons IO. This ObjectInputStream checks whether the object that is deserialized, is allowed or not.

    Read More
    Nov 11, 2020
  • Fix Java Security Issues While Coding in IntelliJ IDEA

    Nowadays, developers are responsible for more than just creating the application. Besides working on features, developers have to focus on their applications’ maintainability, scalability, reliability, and security. Many developers are unsure of where to start with security. In addition, most companies still work with a dedicated security team instead of having security expertise inside the team.

    A lot of developers practically live in their integrated development environment (IDE). A good IDE is like a swiss army knife: it is your go-to tool to do almost everything. Having everything I need to build, run, test, debug, and secure my application, makes a good IDE invaluable for many developers.

    Read More
    Apr 29, 2021
  • Fixing Vulnerabilities in Maven Projects

    Maven is still the most used build system in the Java ecosystem. According to the JVM report 2020, Maven is the number one build tool in the ecosystem with two-thirds of the share.

    Therefore, it is important to now how Maven works. For instance, if you find vulnerabilities in your Maven project using Snyk, how can you fix them?

    Read More
    Oct 20, 2020

Author(s)

  • Brian Vermeer

    Java Champions & Developer Advocate and Software Engineer for Snyk. Passionate about Java, (Pure) Functional Programming, and Cybersecurity. Co-leading the Virtual JUG, NLJUG and DevSecCon community. Brian is also an ... Learn more

Comments (0)

Your email address will not be published. Required fields are marked *

Highlight your code snippets using [code lang="language name"] shortcode. Just insert your code between opening and closing tag: [code lang="java"] code [/code]. Or specify another language.

Save my name, email, and website in this browser for the next time I comment.

Subscribe to foojay updates:

https://foojay.io/feed/
Copied to the clipboard