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So, I am working on something and I wanted to know any ideas on how and what kind of vulnerabilities I can add to a CSV parsing .NET app on the client side before I move on to the server side. So basically there needs to be a vulnerability in the parsing logic of the code which can be exploited by opening it in dotpeek. So I wanted some ideas on how to do so. Right now I am at a point where the app can create csv files based on the things we give in the code*(I give the elements in the code)*, and it can also read a csv file, but the problem is for reading csv file the number of "elements" in the csv files should be known. So I needed some ideas for the vulnerability as mentioned above.

Sai Ganesh K
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  • What kind of "vulnerability" would that be? The main point of memory management in .NET is that you have no risk of the kind of buffer overflows or stack smashing you would have in unmanaged code. You can certainly add *bugs* to the parser where it fails to parse input correctly or crashes, but that's not usually considered a vulnerability (unless as part of a denial of service attack). A vulnerability where an attacker could execute arbitrary code is essentially only possible if you use unsafe code or find a bug in the Framework, neither of which have much to do with parsing CSV. – Jeroen Mostert Nov 10 '22 at 12:30
  • Vulnerability in the csv parsing logic. so think of this as a CTF challenge. there has to be a bug in the parsing logic of the code, which can be bypassed and the flag can be fetched from the server. to figure out how to exploit this vulnerability the user has to understand the code using dotpeek. So needed any idea on what kind of vulneribility can be added to the parsing logic which can help the user exploit it. – Sai Ganesh K Nov 10 '22 at 12:40
  • That's going to be extremely artificial. The only reasonable point of entry would be the location of the CSV file, if you have some kind of mechanism where the attacker can manipulate your program into reading or writing a file it should not access, but then it's likely to simply fail on that file not being CSV. – Jeroen Mostert Nov 10 '22 at 12:43

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DotPeak essentially may retrieve everything since it decompiles the code.

If you want it to be harder use an obfuscator which guards better against decompilation.

One common vulnerability of this is to save hardcoded security information.
Such as db keys, server authentications, user/passwords, etc...

Another classic vulnerability is to read Env variable - so you can add the written CSV file path as an env variable.

You can also add something that will reveal more secret information, for example a configuration key that reveal another header in the CSV if turned on.

Please add more about this exercise, what kind of level are you aiming for, what kind of attacks are you simulating?

SimplyCode
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  • If you have a server - revealing Endpoints may also be something cool to work with. – SimplyCode Nov 10 '22 at 12:43
  • could you elaborate a little bit more. I am new to this and would like a little help on how to proceed. So if you could explain like you would to a beginner it would be helpful. I liked the ideas you told, but how do I implement it, where should I implement it. I would appreciate it if you would help me out a little here – Sai Ganesh K Nov 10 '22 at 12:52
  • And to answer your question on what the aim of this would be is, Essentially the application will do some kind of processing using CSV files CSV file will be the input There will be a bug in the processing code whereby which some validation can be bypassed and the flag can be fetched from the server That's the high level idea To figure out how to exploit the vulnerability, they will have to reverse and understand the C# code – Sai Ganesh K Nov 10 '22 at 12:54
  • @SaiGaneshK To implement vulnerabilities you need to understand them more, Have a look on websites like Rootme: https://www.root-me.org/?lang=en Which can give you some ideas. For the exercise to be interesting you need to get creative with the code you write, so I can't help but suggest few ideas. – SimplyCode Nov 10 '22 at 13:05