Software Reverse Engineering Techniques

Software reverse engineering is done to retrieve the source code of a program because the source code was lost, to study how the program performs certain operations, to improve the performance of a program, to fix a bug (correct an error in the program when the source code is not available), to identify malicious content in a program such as a virus or to adapt a program written for use with one microprocessor for use with another. Reverse engineering for the purpose of copying or duplicating programs may constitute a copyright violation. In some cases, the licensed use of software specifically prohibits reverse engineering.

- De compilers
These are programs which will convert object code back to high level languages such as C.
- Functional Analysis
The input and output states of a chip can be monitored using an oscilloscope, or special purpose probes such as logic state analyzers or protocol analyzers, to acquire a picture of the behavior of the chip over time or in response to input signals.
- Patents
Many patented goods are not sold with restrictive licenses, and hence a bonafide purchaser cannot usually be prevented by the patent from doing what they like with the patented product. Indeed, the patent itself may give the reverse engineer valuable information on how the patented product operates.
- Software anti-tamper technology
It is used to deter both reverse engineering and re-engineering of proprietary software and software-powered systems. In practice, two main types of reverse engineering emerge. In the first case, source code is already available for the software, but higher-level aspects of the program, perhaps poorly documented or documented but no longer valid, are discovered. In the second case, there is no source code available for the software, and any efforts towards discovering one possible source code for the software are regarded as reverse engineering.
- Analysis through observation of information exchange, most prevalent in protocol reverse engineering, which involves using bus analyzers and packet sniffers, for example, for accessing a computer bus or computer network connection and revealing the traffic data thereon. Bus or network behavior can then be analyzed to produce a stand-alone implementation that mimics that behavior.
- Disassembly using a disassembler, meaning the raw machine language of the program is read and understood in its own terms, only with the aid of machine-language mnemonics.

Hardware Reverse Engineering Techniques

Reverse engineering is taking apart an object to see how it works in order to duplicate or enhance the object. The practice, taken from older industries, is now frequently used on computer hardware and software.
Hardware reverse engineering involves taking apart a device to see how it works. In general, hardware reverse engineering requires a great deal of expertise and is quite expensive.

- REFAB (Reverse Engineering - Feature Based)
This tool uses a laser digitizer to scan the part, and the analysis software then analyzes the shape of the part, using features which are based on typical machining operations, to generate a computerized manufacturing description which can be displayed, used to copy the product, or produce new products using the design.

- PRINTED CIRCUIT BOARDS (PCBS)
Computer vision has been widely used to scan PCBs for quality control and inspection purposes, and based on this, there are a number of machine vision for analysing and reverse engineering PCBs.

- INTEGRATED CIRCUIT (IC) COMPONENTS
* The first step is to get through the encapsulating material into the product itself, by chemical etching or grinding.
* Once at the chip surface, each layer of components is photographed, then ground away to reveal the layer below. This process reveals the structure of the chip.
* Although these processes can reveal the structure of the chip, they do not indicate the voltages at each point. However, if the chip is undamaged, voltage contrast electron microscopy can be used to scan the chip in use, and watch the voltage level change over time.
These processes are generally referred to as "stripping" or "peeling" the chip.

Learn software concepts: Overview of Reverse Engineering

Reverse engineering is the attempt to recapture the top level specification by analyzing the product - I call it an "attempt", because it is not possible in practice, or even in theory, to recover everything in the original specification purely by studying the product.

Reverse engineering is difficult and time consuming, but it is getting easier all the time thanks to IT, for two reasons:
- Firstly, as engineering techniques themselves become more computerised, more of the design is due to the computer. Thus, recognisable blocks of code, or groups of circuit elements on a substrate, often occur in many different designs produced by the same computer program. These are easier to recognise and interpret than a customised product would be.
- Secondly, artificial intelligence techniques for pattern recognition, and for parsing and interpretation, have advanced to the point where these and other structures within a product can be recognized automatically.

Reverse engineering generally consists of the following stages:
1. Analysis of the product
2. Generation of an intermediate level product description
3. Human analysis of the product description to produce a specification
4. Generation of a new product using the specification.
There is thus a chain of events between the underlying design specification and any intermediate level design documents lying behind the product, through the product itself, through the reverse engineered product description, through the reverse engineered specification, and into the new product itself.

Reasons for reverse engineering:

- Interoperability.
- Lost documentation: Reverse engineering often is done because the documentation of a particular device has been lost (or was never written), and the person who built it is no longer available. Integrated circuits often seem to have been designed on obsolete, proprietary systems, which means that the only way to incorporate the functionality into new technology is to reverse-engineer the existing chip and then re-design it.
- Product analysis : To examine how a product works, what components it consists of, estimate costs, and identify potential patent infringement.
- Digital update/correction : To update the digital version (e.g. CAD model) of an object to match an "as-built" condition.
- Security auditing.
- Military or commercial espionage : Learning about an enemy's or competitor's latest research by stealing or capturing a prototype and dismantling it.
- Removal of copy protection, circumvention of access restrictions.
- Creation of unlicensed/unapproved duplicates.
- Academic/learning purposes.
- Curiosity.
- Competitive technical intelligence.
- Learning.