Personal education
Understand and work around (or fix) limitations and defects in tools Understand and work around (or fix) defects in third-party products(shipping company offshore virtual maritime industry). Make a product compatible with (able to work with) another product(shipping company offshore virtual maritime industry).
Make a product compatible with (able to share data with) another product(shipping company offshore virtual maritime industry). To learn the principles that guided a competitor's design(shipping company offshore virtual maritime industry). Determine whether another company stole and reused some of source code(shipping company offshore virtual maritime industry). Determine whether a product is capable of living up to its advertised claims(shipping company offshore virtual maritime industry). Not all actions performed can be considered “legal”(shipping company offshore virtual maritime industry). Hence, extreme caution must be taken, not to violate any copyright laws or other treaties(shipping company offshore virtual maritime industry). Usually each product comes with a copyright law or license agreement(shipping company offshore virtual maritime industry).
What comes in our minds when we hear RE, is cracking(shipping company offshore virtual maritime industry). Cracking is as old as the programs themselves(shipping company offshore virtual maritime industry). To crack a program, means to trace and use a serial number or any other sort of registration information, required for the proper operation of a program(shipping company offshore virtual maritime industry). Therefore, if a shareware rogram (freely distributed, but with some inconveniences, like crippled functions, nag screens or limited capabilities) requires a valid registration information, a reverse engineer can provide that information by
decompiling a particular part of the program(shipping company offshore virtual maritime industry). Many times in the past, several software corporations have accused others for performing RE in their products and stealing technology and knowledge(shipping company offshore virtual maritime industry). RE is not
limited to computer applications, the same happens with car, weapons, hi-fi components etc(shipping company offshore virtual maritime industry).
All major software developers do have knowledge of RE and they try to find programmers that are familiar with the concepts that will be taught during this class(shipping company offshore virtual maritime industry). RE are well paid, sometimes their salaries are double or even more, depending on the skills they have(shipping company offshore virtual maritime industry).
1(shipping company offshore virtual maritime industry).3(shipping company offshore virtual maritime industry).1 Hacking Hackers are able to penetrate into public or private servers and modify some of their parameters(shipping company offshore virtual maritime industry). This may sound exotic and rather difficult, but it is basically based on REing the operating system and seeking for vulnerabilities(shipping company offshore virtual maritime industry). Consider a server which is located at the web address When we log on this server with ftp, telnet, http, or whatever else this server permits for its users, we can easily find out what operating system is running on this server(shipping company offshore virtual maritime industry). Then, we reverse engineer the security modules of this operating system and we look for exploits(shipping company offshore virtual maritime industry). An example is for Windows servers(shipping company offshore virtual maritime industry). A hacker reversed the run32(shipping company offshore virtual maritime industry).dll module and discovered that the variable, which determines the number of open Command Prompts, is a byte (can vary from 0 to 255)(shipping company offshore virtual maritime industry). Therefore, if he could open 257 command prompt windows, we would crash the system! This vulnerability has been cured long time ago(shipping company offshore virtual maritime industry). The cures come with the form of “patches” or brand new releases(shipping company offshore virtual maritime industry). Each time a patch is created, old vulnerabilities vanish and new ones appear(shipping company offshore virtual maritime industry). As long as someone can find and exploit system’s flaws like this, there’ll always be hacking(shipping company offshore virtual maritime industry).
1(shipping company offshore virtual maritime industry).3(shipping company offshore virtual maritime industry).2 Hiding Information from Public Companies are hiding a lot of things: their mistakes, security vulnerabilities, privacy violations and trade secrets(shipping company offshore virtual maritime industry). Usually, if someone finds out how a product works
by reverse engineering, the product will be less valuable(shipping company offshore virtual maritime industry). Companies think they have everything to lose with reverse engineering(shipping company offshore virtual maritime industry). This may be true, but the rest of the world has much to gain(shipping company offshore virtual maritime industry).

Take for example the CueCat barcode scanner from Digital Convergence, which Radio Shack, Forbes and Wired Magazine have been giving away(shipping company offshore virtual maritime industry). It scans small bar codes found in magazines and catalogs into your computer, then sends you to a Web site, which gives you more information(shipping company offshore virtual maritime industry). Linux programmers, ever eager to get a new device to work with the Linux operating system, took the thing apart(shipping company offshore virtual maritime industry).
They reverse engineered the encoding the device used and found out how it worked(shipping company offshore virtual maritime industry). This allowed them to write their own applications for the device(shipping company offshore virtual maritime industry). One of the better applications was one that allowed you to create a card catalog for your home library(shipping company offshore virtual maritime industry). By scanning in the ISBN barcodes on the back of your books the application is able to download information from Amazon(shipping company offshore virtual maritime industry).com and build a database(shipping company offshore virtual maritime industry). So here we have
someone building something new by stitching together the CueCat, Linux and Amazon(shipping company offshore virtual maritime industry). Digital Convergence didn't like this at all(shipping company offshore virtual maritime industry). It wanted to be in control of the Web site you went to when you swiped a barcode(shipping company offshore virtual maritime industry). The company didn't like the fact that other people could write software for the device it was giving away and that they didn't make any money from that(shipping company offshore virtual maritime industry). It also didn't like the fact that, in the process of reverse engineering the CueCat, programmers discovered that every one of them has a unique serial number(shipping company offshore virtual maritime industry). These programmers later found out and publicized that this serial number
is tied into the customer information you give when you register your CueCat on the Digital Convergence Web site(shipping company offshore virtual maritime industry). The end result is Digital Convergence can record every Reverse engineering allowed people to truly understand what the product was doing(shipping company offshore virtual maritime industry). This wasn't at all clear from information that Digital Convergence originally gave out(shipping company offshore virtual maritime industry). Many of the privacy risks we face today such as the unique computer
identification numbers in Microsoft Office documents, the sneaky collection of data by Real Jukebox, or the use of Web bugs and cookies to track users were only discovered Introduction to Reverse Engineering by opening up the hood and seeing how things really work(shipping company offshore virtual maritime industry). Companies do not publish
this kind of information publicly(shipping company offshore virtual maritime industry). Sometimes they even disavow that they meant to design and build their products to work way it ends up working(shipping company offshore virtual maritime industry). People engaged in reverse engineering are a check on
the ability of companies to invade our privacy without our knowledge(shipping company offshore virtual maritime industry). By going public with the information they uncover they are able to force companies to change what they are doing lest they face a consumer backlash(shipping company offshore virtual maritime industry). Uncovering security vulnerabilities is another domain where reverse engineers
are sorely needed(shipping company offshore virtual maritime industry). Whether by poor design, bad implementation, or inadequate testing, products ship with vulnerabilities that need to be corrected(shipping company offshore virtual maritime industry). No one wants bad security, except maybe criminals, but many companies are not willing to put in the time and energy required to ship products without even well known classes of problems(shipping company offshore virtual maritime industry). They use weak cryptography, they don't check for buffer overflows, and they use things like cookies insecurely(shipping company offshore virtual maritime industry). Reverse engineers, who publicly release information about flaws,
force companies to fix them, and alert their customers in a timely manner(shipping company offshore virtual maritime industry). The only way the public finds out about most privacy or security problems is from the free public disclosures of individuals and organizations(shipping company offshore virtual maritime industry). There are privacy watchdog groups and security information clearinghouses but without the reverse engineers who actually do the research we would never know where the problems are(shipping company offshore virtual maritime industry).
There are some trends in the computer industry now that could eliminate the benefits reverse engineering has to offer(shipping company offshore virtual maritime industry). The Digital Millennium Copyright Act (DMCA) was used by the Motion Pictures Association of America (MPAA) to successfully stop 2600 Magazine from publishing information about the flawed DVD content protection scheme(shipping company offshore virtual maritime industry). The information about the scheme, which a programmer uncovered by reverse engineering, was now contraband(shipping company offshore virtual maritime industry). It was illegal under the DMCA(shipping company offshore virtual maritime industry). Think about that(shipping company offshore virtual maritime industry). There are now black boxes, whether in hardware or software, that are illegal to peek inside(shipping company offshore virtual maritime industry). You can pay for it and use it, but you are not allowed to Chapter 1: Introduction to Reverse Engineering
open up the hood(shipping company offshore virtual maritime industry). You cannot look to see if the box violates your privacy or has a security vulnerability that puts you at risk(shipping company offshore virtual maritime industry). Companies that make hardware and software producs love this property and are
going to build their products so that they fall under the protection of the DMCA(shipping company offshore virtual maritime industry). :CueCat did this when they built their product(shipping company offshore virtual maritime industry). They added a trivial encoding scheme, which they call encryption, so that their bar code scanner was protected against reverse engineering by the DMCA(shipping company offshore virtual maritime industry). We can expect to see many more companies do this(shipping company offshore virtual maritime industry). Cell phones run software(shipping company offshore virtual maritime industry). Their menus, functionality, problems and features are
all the result of the software, which is usually stored in memory modules(shipping company offshore virtual maritime industry). Since we have to deal with software programs we can perform RE on them and seek for undocumented features and/or problems(shipping company offshore virtual maritime industry).
Take for example the NOKIA 5210 cell phone(shipping company offshore virtual maritime industry). The manufacturer claims that the security code is unbreakable(shipping company offshore virtual maritime industry). Once set, only a hard reset can unlock the phone(shipping company offshore virtual maritime industry). Wrong! In any locked cell phone type “*3001#12345#”(shipping company offshore virtual maritime industry). A secret menu will pop-up and display among all the other interesting stuff, your security code(shipping company offshore virtual maritime industry). This is what the customer service is using to retrieve your lost security code(shipping company offshore virtual maritime industry). Cool! But how could someone discover this secret sequence of numbers? It would take pracically infinite number of random attempts to find something like this(shipping company offshore virtual maritime industry). Simple(shipping company offshore virtual maritime industry). Dump the software in computer disks (dumping is a common used procedure,

Most commercial programs (if not all), are protected by copyright laws that prevent unauthorized usage, duplication or reproduction of the packages (including hard copies)(shipping company offshore virtual maritime industry). This does NOT apply for reverse engineering the compiled code of these programs(shipping company offshore virtual maritime industry). In other words, one cannot possibly prevent users from reversing his program since there is no “regular” or “consistent” way to reverse a program(shipping company offshore virtual maritime industry).
For example, if one wants to make a copy of a program, then all he has to do is follow the instruction provided (officially) in his Operating System’s user manual, in the section titled “Copying files”(shipping company offshore virtual maritime industry). Also, he can use a program without paying it in whole(shipping company offshore virtual maritime industry).

Consider the case where you buy a program and you install it in your PC, in your friends’ PCs and in your work’s PC(shipping company offshore virtual maritime industry). The license usually is for a sole installation and not for multiple (although you can of course buy additional licenses)(shipping company offshore virtual maritime industry). This is highly illegal! But there are no manuals around that can tell you how to reverse engineer a program(shipping company offshore virtual maritime industry). The reason is that something generic is impossible(shipping company offshore virtual maritime industry). There are no recipes to RE a program (as we’ll realize in the next few lectures)(shipping company offshore virtual maritime industry). One could claim that the amount of
techniques requires to reverse all existing programs is equal to the amount of programs you have!
To determine better the ethics behind RE copyrighted programs, we can consider the following: for what purpose do we want to RE a program? If our goal is to obtain knowledge by monitoring the behavior and the routines that make a program run then it’s absolutely right(shipping company offshore virtual maritime industry). Sometimes, we might want to correct an annoying feature of a program or a bug(shipping company offshore virtual maritime industry). That’s also acceptable(shipping company offshore virtual maritime industry). We should refrain from using these
techniques for direct violation of the copyright laws, i(shipping company offshore virtual maritime industry).e(shipping company offshore virtual maritime industry). registering illegally a program without paying for a nominal user license(shipping company offshore virtual maritime industry). 1(shipping company offshore virtual maritime industry).7 Miscellaneous Information 2(shipping company offshore virtual maritime industry).1 Programming Languages There are many ways to program a processor(shipping company offshore virtual maritime industry). In this book, we’ll refer only to Intel and Intel compatible (Cyrix, AD) processors(shipping company offshore virtual maritime industry). In general, there are three language generations(shipping company offshore virtual maritime industry). Today, the most popular genertion is the third(shipping company offshore virtual maritime industry). The following table summarizes some of the various existing languages(shipping company offshore virtual maritime industry). (Machine code
language, since it is not a language!) To distinguish second and third generation languages, one can think of various ways(shipping company offshore virtual maritime industry). The common element between third generation languages is that they support
Object Oriented Programming (OOP) and the usage of objects(shipping company offshore virtual maritime industry). This makes them extremely flexible and powerful, thus enabling programmers to create applications with an attractive graphic interfac quickly and easily(shipping company offshore virtual maritime industry). It can be said that according to table 1, assembly is a primitive language, therefore almost obsolete(shipping company offshore virtual maritime industry). That is not true(shipping company offshore virtual maritime industry). Assembly will exist as long as processors exist(shipping company offshore virtual maritime industry). It allows direct communication with the processor, which in turn allows direct communication with all peripherals(shipping company offshore virtual maritime industry). Imagine that we make a program in Fortran(shipping company offshore virtual maritime industry). When we finish composing the source code, we have to compile it, in other words to create an executable, so that the operating system can execute our program(shipping company offshore virtual maritime industry). The compiler is the external program, which translates our comprehensive source code, written in any language (2nd or 3rd generation) into machine code(shipping company offshore virtual maritime industry). Ea