By noticing these addresses, we can select a point in which we believe to be within process owned memory that lies on the exit procedure flow. This is achieved by understanding that all return addresses are stored on the stack along an execution path so that the program knows where to return to. We can find a reasonable point of execution further up the stack in which still lies on the path after clicking the “X” to exit the program.
The following diagram highlights the concept of redirecting traffic flow to our malicious content.įrom observing the stack, we can now see the nest of calls made up until this point of execution.
#Bitburner the cave code#
In this paper, we will find where that exit branch is and find an arbitrary point to redirect flow to our code cave. In most cases, a user will need to exit the process so a click of the “X” at the top right of an application is generally the way - doing so will trigger the exit branch code. If we use the exit procedure instead and require user interaction, an automated script will find it difficult to trigger our payload and analyse its behaviour. However, some virtualisation engines can make use of the system clock to speed up this process.
#Bitburner the cave software#
There were many suggested methods to bypass virtualisation such as using a delay upon opening software before launching the malicious code in hope that it times out. A common malicious behaviour that is detected is the attempt to connect out of the system to the internet.
Generally, these detection systems will either be signature based or try to run the software and detect any malicious behaviour. The reason as to why I chose the exit procedure is due to how a lot of anti-virus scanners as well as virtualisation agents operate. In this scenario, I will be hooking a point in the path of execution flow that the exiting of the program had triggered. This is a basic method and is taught in most tutorials and involves the use of code caves which will be discussed later on in the paper. In this particular post, I will be focusing on the basics of shell code injection by redirecting code execution flow.
#Bitburner the cave manual#
I have decided to create this post as an introductory tutorial to manual back door injection into executables. We can re-use existing software by taking the existing start-up programs or system services on the target system and add our malicious code.
The notion of executable back doors are often a strong method that can provide persistence without the addition of a new start-up program or system service. The process required to create such an executable requires modification so that when it is running, it provides a door which allows an attacker to penetrate the system. By utilising a back door in an executable, we are creating a Trojan horse. This paper presents the concept of hooking ExitProcess to redirect execution flow and bypasses VirusTotal reasonably well at a 89% evasion rate.Ī backdoor is an alternate path that allows an attacker to compromise a system. This process does not utilize any advanced mechanisms such as shell code obfuscation, code cave region splitting or ROP. This method approaches a basic technique in a diverse way. Note: this post was made in September 2015
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