By manipulating the size of data removed from the end of the file and gradually narrowing down the spot where detection of the file as virus infected stops, you will be able to find the location of the file signature. The process of doing this is actually quite straightforward and involves removing different lengths of data from the end of the file and scanning each copy of the file with your AV program of choice to identify which copies of the file are detected as infected.
![netcat windows location netcat windows location](https://1.bp.blogspot.com/-3bYo7FbDNxM/Xi24L6ro3rI/AAAAAAAAifo/Ah212b1PrY05DDo91z81Rf_mT6Htao3RACLcBGAsYHQ/s1600/10.png)
Finding File Signatures Considering the focus so far on file signatures, it might be worthwhile to discuss how we actually go about finding what the signature of a file actually is.
![netcat windows location netcat windows location](https://hakin9.org/wp-content/uploads/2020/06/Screen-Shot-2020-06-05-at-10.19.51.png)
If you are interested in some of the other methods of virus detection, "The Art of Computer Virus Research and Defense" by Peter Szor is an excellent reference. The methods of AV avoidance discussed in this post are primarily focused on the file signature method, but some might also be effective (with a little modification) against other detection methods. Now, checking for this type of file signature is not the only technique used by virus scanning products to detect malicious code, however it is the most common, and in the majority of cases it is sufficient to modify the file signature in order to bypass detection. Consequently, detection can also be bypassed if the file appears one way when opened from disk, but modifies itself when loaded into memory. Another important fact to understand about Virus Scanners related to the file signature issue is that the "scanning" of the file is usually done based on how it appears on disk. Now it may not always be possible to just directly modify the file signature in such a simple manner and still have the target executable run as intended, but there are other ways in which this same goal can be achieved other than just replacing text characters (more on this later). This could be as simple as the virus scanner expecting to see the characters "Now you are pwned!" at byte offset 200 in the file, and if you change the file to instead say "Now you are Pwned!" (changing the case of the 'p' in pwned), the signature will not be complete and no virus will be detected. This signature is usually quite small (perhaps only a few dozen bytes), and if you can modify the file such that those bytes are not present in the file when the virus scanner scans it, then no virus will be detected. The most common method for virus detection is the use of a signature, which is a unique pattern of bytes contained within a malicious file. A quick explanation of what a signature is could be helpful here. Virus "File Signatures" What these methods all have in common is that they all work to try and modify the file signature of the target executable file in order to avoid detection. Methods of Bypassing AV Detection The methods for bypassing AV detection can be loosely grouped together as follows: And of course I also have to give the standard warning here that I do before any post that may be put to inappropriate use. This can be effective in bypassing AV detection on content inspection gateways (virus scanning email servers for example), but a local virus scanner will usually pick the file up once it is extracted to disk before being run.
![netcat windows location netcat windows location](https://i2.wp.com/gbhackers.com/wp-content/uploads/2017/11/nc7.png)
This is because this method results in a program that cannot be run in its current form - it will need to be removed from the encrypted container first before it is run.
#Netcat windows location password
In addition, while it is possible to evade AV detection by encrypting a file (adding it to a TrueCrypt container, or a password protected zip file) I have not listed this method below. The methods I am listing are specifically focused on Windows executable files, with nc.exe being used as the example, and may not be appropriate for other types of malicious code, such as macro viruses, although the theory (involving signature avoidance) is largely the same. Since this was something I had looked at before, I contributed some of my own favorite methods to the list, but I thought it might also be a good idea to do a post about it here as well, giving a more detailed summary of the process, including my own methods and those mentioned by some others. In this particular case, the executable in question that people wanted to sneak by those evil AV scanners was the Windows version of netcat (nc.exe). Introduction The subject of bypassing AV detection is one that comes up quite frequently in discussions in pentesting circles, and I was most recently reminded of it once again when it came up on one of the mailing lists I subscribed to.