The A’s did not escape the buffer space and thus, no buffer overflow occurred. In the above example, you can see that a a number of A’s (x41) were sent to the buffer space, but were correctly sanitized. ![]() Another way to think of this is that information placed into the buffer space should stop at the EBP as such: With proper input sanitation, information placed into the buffer space should never travel outside of the buffer space itself. Buffer space is used as a storage area for memory in some coding languages. The 4 components above actually sit in order from top to bottom.įor the scope of this tutorial, we really need to be concerned with buffer space and the EIP. Extended Instruction Pointer (EIP) / Return Address When we look into the memory stack, we will find 4 main components:Ĥ. – Mona Modules installed in your Immunity Debugger folder – Immunity Debugger installed on your Windows machine – Vulnserver installed on your Windows machine Your favorite hacking VM (I’ll be using Kali Linux) A Windows machine (preferably Windows 10) My goal is that by the end of this tutorial, the average reader will have a clearer understanding and less fear of buffer overflows. For most people breaking into cyber security, buffer overflows can be hard for someone to wrap their mind around. Hello everyone! I thought it would be helpful to provide a walkthrough of a 32-bit Windows buffer overflow. This video covers how to correctly generate shellcode for buffer overflows, which will allow us to gain shell access to our victim machine. This video covers how to find the right module in buffer overflows, which will allow us to avoid memory protections (such a DEP, ASLR, etc.) and find a valid return address. We will examine the ESP dump and learn what bad characters look like, how they interact with shellcode, and their importance. This video covers how to find the find bad characters in a buffer overflow process. This video covers how to control and overwrite the EIP in buffer overflows, which will lead to malicious code execution. This video covers how to find the EIP offset in buffer overflows, which will allow us to point to malicious shellcode later on. ![]() ![]() This video covers the art of fuzzing in buffer overflows, which allows us to identify if a command is vulnerable in software and approximately how many bytes it takes for an overflow. This video covers the art of spiking in buffer overflows, which allows us to identify vulnerable commands within a program. In future course videos, we will be covering: I also highlight important aspects, such as the anatomy of memory and the anatomy of the stack. It may seem like everything is OK but as soon as your PaaS hosted site is put under load, you'll quickly find that having file system writes happening will cause things to go wrong so it's worth confirming your configuration.This video presents the material that will be covered in my course, Buffer Overflows Made Easy. Seems obvious but a simple bit of configuration somewhere which is not set quite right can have you scratching your head. Unicorn Serialisation - if you're using it, ensure that there is nothing which is being tracked by unicorn in the content tree (or anywhere else) which a content author might be making updates to (and therefor writing to the unicorn file). On a local instance we're referring to these logs/artefacts which is controlled by the \App_config\Include\ file so set this to ".disabled" by default for PaaS environments. Logging - ensure you're using Application Insights and that all other logging is routed to AI and definitely not to the file system.ĭiagnostic logging - disable this for production environments and only enable if you have a need (I've never used this but it's enabled by default which caught me out). Sitecore on Azure PaaS File I/O errors "Too many changes at once in directory:D:\home\site\wwwroot\"Įach time I've had to trawl through the Azure Kudo powershell file system view looking for where on earth some files are being written to so I thought I'd share a couple of (seemingly obvious upon reflection) places where I've had to work around this. During the move to Azure PaaS there have been a few instances where we've noticed a series of errors being logged about file I/O issues which often result in instances dying within a PaaS "load balancer".
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