The EX4 and the MQ4 files are associated with the MetaTrader 4 trading platform. They both are vital in the online trading at FOREX market. These files can contain program code of expert advisors (EA), indicators or scripts. The difference between them lies in the fact that the files of the first type are executable (*.EX4) and *.MQ4 files contain a source code. Availability of source code in this case is critically important for several reasons. Here are some of them:

• This allows you to understand the logic of the trading program, its algorithm. It is very important because you trust this program to manage your money.
• This enables modify the source code and thereby change the algorithm of EA in accordance with current market requirements.
• This makes it possible to remove any restrictions imposed by developers, such as limiting the time of work or number of trading accounts.

Some developers betweentimes forget to attach the source code to its products. In these cases requires a decompilation, i.e. files translation from .EX4 to .MQ4 format.

Until recently a decompilation has not been a big problem. It cost less than $10 and took about a minute. There are even standalone tool for decompilation called «EX4 decompiler».

Now it's different. Starting from MetaTrader 4 build 600, MQ4 files compile to native code (like DLL). As a result the EX4 decompiler unfortunately can no longer be used.

Code optimization and compression are generally used during compilation process of the new terminal builds (600 & above). Code obfuscation is also used at compile time, and this fact greatly complicates the work to be done. Nevertheless MetaTrader Market products are encrypted additionally. These obstacles make the classical methods of reengineering (such as disassembly and static code analysis) ineffective.

Therefore, in order to recover the source code completely, these days it is necessary to work directly with a memory dumps, use debugger for the terminal and overcome restrictions of execution environment virtualization.

This painstaking work requires time and strong effort. But with due perseverance, success remains the option to achieve.

Given the above, it becomes clear that it is impossible to develop a standalone decompiler. But on the other hand, it's possible to create robust service for decompilation. And that is what we successfully did.