All about Software Cracking

Software cracking

Software cracking is the modification of software to remove protection methods: copy prevention, trial/demo version, serial number, hardware key, CD check or software annoyances like nag screens and adware

Legality

The distribution and use of cracked copies is illegal in almost every developed country. There have been many lawsuits over cracking software, but most have been to do with the distribution of the duplicated product rather than the process of defeating the protection, due to the difficulty of constructing legally sound proof of individual guilt in the latter instance. In the United States, the passing of the Digital Millennium Copyright Act (DMCA) legislation made software cracking, as well as the distribution of information which enables software cracking, illegal. However, the law has hardly been tested in the U.S. judiciary in cases of reverse engineering for personal use only. The European Union passed the European Union Copyright Directive in May 2001, making software copyright infringement illegal in member states once national legislation has been enacted pursuant to the directive.


Methods

The most common software crack is the modification of an application's binary to cause or prevent a specific key branch in the program's execution. This is accomplished by reverse engineering the compiled program code using a debugger such as SoftICE, OllyDbg, GDB, or MacsBug until the software cracker reaches the subroutine that contains the primary method of protecting the software (or by disassembling an executable file with a program such as IDA). The binary is then modified using the debugger or a hex editor in a manner that replaces a prior branching opcode with its complement or a NOP opcode so the key branch will either always execute a specific subroutine or skip over it. Almost all common software cracks are a variation of this type. Proprietary software developers are constantly developing techniques such as code obfuscation, encryption, and self-modifying code to make this modification increasingly difficult.

A specific example of this technique is a crack that removes the expiration period from a time-limited trial of an application. These cracks are usually programs that patch the program executable and sometimes the .dll or .so linked to the application. Similar cracks are available for software that requires a hardware dongle. A company can also break the copy preventions of programs that they have legally purchased but that are licensed to particular hardware, so that there is no risk of downtime due to hardware failure (and, of course, no need to restrict oneself to running the software on bought hardware only).

In other cases, it might be possible to decompile a program in order to get access to the original source code or code on a level higher than machine code. This is often possible with scripting languages. An example is cracking (or debugging) on the .NET platform where one might consider manipulating CIL to achieve one's needs.
There are a number of sites on the Internet that let users download cracks for popular games and applications (although at the danger of acquiring malicious software that is sometimes distributed via such sites). Although these cracks are used by legal buyers of software they can also be used by people who have downloaded or otherwise obtained pirated software (often through P2P networks).

Effects

The most visible and controversial effect of software cracking is the releasing of fully operable proprietary software without any copy protection. Software companies represented by the Business Software Alliance estimate and claim losses due to piracy.

Cracking has also been a significant factor in the domination of companies such as Adobe Systems and Microsoft, all of whom have benefited from piracy since the 1980s. Vast numbers of college and high school students adopted readily available applications from these companies. Many of these students would then go on to use them in their professional lives, purchasing legitimate licenses for business use and introducing the software to others until the programs became ubiquitous.