WHAT IS A DLL FILE USED FOR .DLL
WHAT IS A DLL FILE USED FOR MANUAL
WHAT IS A DLL FILE USED FOR PATCH
WHAT IS A DLL FILE USED FOR SOFTWARE
WHAT IS A DLL FILE USED FOR FREE

After that it does a bunch of other stuff neutralizing the other protections.

Having decrypted all the sections, the DLL now dumps the process' image onto the disk and reconstructs the import information.

After having done so, for every subsequent call to the hooked function, it simply returns 1 as though the call was successful.

To make this work, the hooked function has to pass on the calls to the proper function in the DLL for these calls.

The hooked function then calls Func for each encrypted section, instructing it to decrypt each section.

The hooked function inspects the return address on the stack two frames up to figure out the starting address of the function (call it Func) that called it.

GetProcAddress hook waits for a specific string to be supplied and then returns its own hooked version of that function.

DLL hooks GetProcAddress in the program's IAT.

I employed a DLL injection-based solution that worked as follows: All of the components were digitally signed.

To request encryption or decryption of a given section, the program shipped with a DLL that exported a function which took as arguments the number of the section and a Boolean that indicated whether the section should be encrypted or decrypted.

WHAT IS A DLL FILE USED FOR SOFTWARE

The software included a kernel module which performed the run-time encryption/decryption. The program had a number of sections in it that were encrypted on disk after compilation time and had to be decrypted at run-time. I had a recurring interest in a program that was updated very frequently (sometimes multiple times daily). The following example is necessarily vague in some respects because of non-disclosure agreements. (The comment about cryptographic signatures applies to the executable on disk, not in memory of course, altering the contents in memory would affect a cryptographic signature computed on the altered memory contents.)ĭLL injection can be employed to solve highly non-trivial reverse engineering problems. It also makes binary modification fast and simple, and does not alter cryptographic signatures of the executable that you are patching.

WHAT IS A DLL FILE USED FOR .DLL

DLL injection almost entirely eliminates the need for using assembly language while making modifications to a binary the only assembly language needed will be small pieces of code nearby the entrance and exit to a particular hook to save and restore the values of registers / the flags.

WHAT IS A DLL FILE USED FOR MANUAL

Except DLL injection will probably be easier and faster, because you get to code your patches in C instead of assembly language and do not have to labor over making manual modifications to the binary and its PE structure, finding code caves, etc. This technique is frequently used within the game hacking world to code bots.Īnything that you could do with byte patching, you can do with DLL injection.

WHAT IS A DLL FILE USED FOR FREE

Given the fact that you have free reign to execute whatever code that you want within the process' address space, you can modify the program in any way that you choose.

This provides you a data source that can assist in rapidly reverse engineering the target.ĭLL injection is not limited to logging, though. For example, you can hook the IAT entry for a given imported operating system library function, and then log the function arguments onto disk. It's very commonly used for logging information while reverse engineering. My DLL does its business within the individual hooks, and then is programmed to redirect control back to the original process.ĭLL injection provides a platform for manipulating the execution of a running process. I can even do very surgical and targeted hooks at arbitrary locations, akin to old-school byte patching.

WHAT IS A DLL FILE USED FOR PATCH

If I want to do the same with respect to some function that exists within the binary, I will make some sort of detours-style patch at the beginning of the function. If I am interested in modifying or observing the process' interaction with some imported function, then I will overwrite the IAT (Import Address Table) entry for that function and replace it with a pointer to something that I control. In the entrypoint, I will then invoke a routine that performs in-memory patching of all of the locations within the original binary that interest me, and redirects their execution into my DLL via a variety of modifications. From there, the entrypoint of the DLL will be executed by the operating system once it is loaded. To expand somewhat, I most often use DLL injection in the context of forcing an existing process to load a DLL through CreateRemoteThread.

What is a dll file used for