Have you ever gate-crashed a wedding? I once did. It was back in college, I think it was my freshman year. I was hungry and wanted to find something to eat. I was walking down the street and there was this group of well-dressed people entering an event center that was close to my residential hall. I just had this idea that I could get a free lunch so I followed them. The music was loud and there was a lot of dancing so I joined in the dance. I got the lunch pack and a very nice drink and immediately found my way out of the center. I had no idea who go married and was so happy I didn’t accidentally run into my Mom or a known relative at the wedding; I would have been in some form of trouble.
How in the world was I able to gatecrash that wedding? I think of one main reason; there was no one at the door checking the guests to see if they were allowed into the venue and I think they did not really care about it. It was good that I was just a hungry college student. This is what a lack of input validation can do to critical systems and data in your organization.
My colleagues and I usually talk about XML attacks and other kinds of injections but I had never heard about XSLT injections. I decided to learn more and these are some of my findings.
XSLT (Extensible Stylesheet Language Transformations) is a language used for transforming XML documents into other formats, such as HTML or XML with different formatting. It is commonly used for presenting XML data on the web, as it allows developers to control how data is displayed by creating templates that define the structure and layout of the output.
However, XSLT can also be vulnerable to injection attacks if an attacker is able to inject malicious XSLT code into an application that processes XSLT. This can allow the attacker to execute arbitrary code on the server or manipulate the data being transformed in undesirable ways.
To prevent XSLT injection attacks, it is important to properly sanitize any user input that is used in an XSLT transformation. This can be done by ensuring that input is properly validated and escaped to prevent malicious code from being executed. It is also a good idea to limit the functionality of the XSLT transformation to only what is necessary for the application, as this can reduce the potential attack surface.
Overall, XSLT is a powerful tool for transforming and presenting XML data, but it is important to be aware of the potential for injection attacks and take steps to prevent them.
It’s not so easy to gate-crash weddings as it was some years ago, but I hope this post sensitizes you and your programmers to pay more attention to enforcing proper input validation in your application development. Your auditors and assessors should also be looking out for injection flaws and might do a risk assessment to learn if they need to add XSLT injections to their list of possible attacks if they need to.
For more details on possible attacks related to XSLT injections, please check out Shivam Bathla’s blog post at pentesteracademy.com/