Thermite Hard Disk Destruction Security Center Mayank Tewari mayank@desdevpro.com http://www.desdevpro.com 10 Aug 2009 Security Thermite Hard Disk Track erase How often have we seen in the movies or videos, people trying to destroy their hard drives using magnets and drills to prevent them from falling into wrong hands(FBI, CIA, etc.). Well ofcourse these all do work but there is always a scope for more. There can be a possibility that the hard drive is rendered such that it can never be used again, for example lets just melt it away. Luckily we have a pretty cool yet hot way to get this done. So lets see what it takes to completely obliterate a drive. Disclaimer This article is intended for educational purposes only. The purpose of this article is to make you aware of common attack procedures so that you can build appropriate defenses against them. DesDevPro does NOT encourage using these methods to harm other people, their data or machines. Such actions are punishable by law. By reading this disclaimer you accept: To not use this information to gain access to and/or damage unauthorised hardware or software. To use the tools and/or techniques mentioned herein at your own risk. DesDevPro.com, its members, and the author of this content claim no responsibility for any damages resulting from the use of this material. What is Thermite img1.jpg Hello everyone, how often have we seen in the movies or videos, people trying to destroy their hard drives using magnets and drills to prevent them from falling into wrong hands(FBI, CIA, etc.). Well ofcourse these all do work but there is always a scope for more. There can be a possibility that the hard drive is rendered such that it can never be used again, for example lets just melt it away. Luckily we have a pretty cool yet hot way to get this done. So lets see what it takes to completely obliterate a drive. With the amount of personal data stored on our computers, we all understand the importance of destroying that data before disposing it off. There are many ways to destroy a hard drive for example: softwares, physical disassembling, drills, hammers, magnets or electromagnets, acids, etc. but none are quite as outrageous or dangerous as thermite. img2.jpg A couple different methods of containing the thermite above the hard drive exist but the best way is a clay flower pot with the drip tray for a lid. Molding a cement container can also be an option. Since thermite is extremely hard to ignite, sparklers or magnesium ribbons can offfer a very reliable method of ignition. The goal is to completely destroy the drive while it is still in the computer case. The theoretical application is to destroy the disk at a moments notice so it won’t fall into the wrong hands(FBI, etc.) . Placing about 1 pound of thermite in a clay flower pot and lighting it from the drain hole in the bottom yields the best results. This could easily be placed in the 5.25″ bays above the drive. Some Chemistry A thermite reaction is a process in which the correct mixture of metallic fuels are combined with a metal oxidizer and ignited. The ignition here itself requires extremely high temperatures, but once ignited, thermite supplies its own source of oxygen. It can potentially burn underwater if mixed properly. img3.jpg Thermite is usually used for welding purposes, but it can be used for other purposes(such as this one) too. The most common thermite is “black or blue iron oxide (Fe3O4), produced by oxidizing iron in an oxygen-rich environment under high heat” and Aluminum(Al). Red iron(III) oxide (Fe2O3), commonly known as rust, can also be used. There are many chemicals that can make thermite; the mixtures used to make thermite therefore vary. Since the oxidation of one substance involves the reduction of another, this type of reaction is often called redox reaction. This reaction is also called a displacement reaction because Al displaces Fe in the oxide. Because of the nature of this reaction, the correct ratio of substances is important to ensure the optimum amounts of fuel (aluminum) and oxygen (iron oxide) within the mixture. Thermite is very safe to handle because of the high ignition temperatures required. An electric pyrogen igniter would be a far better choice for ignition, instead of the unreliable methods. img4.jpg There are two important aspects to ensure a successful reaction. Even mixing and smallest possible powder particle size. If thermite is not adequately mixed, it may be difficult to ignite or maintain the reaction. One problem when mixing thermite is the difference in weight between the aluminum and the iron oxide. This causes them to separate out rendering the thermite useless.Powder particle size is measured with a measurement called mesh. Passing the powder through a mesh will determine the largest particle size, this reaction performs best with the smallest obtainable mesh size. The mesh size for aluminum should be near about 1200 mesh and black iron oxide of about 300 mesh. img5.jpg The total enthalpy or heat content released is -3.677 kJoule per gram of Fe3O4/AL thermite. The ratio of Fe3O4 to aluminum powder by weight is about 3.22 to 1, according to the reaction's stoichometry. Using about 200 grams of Aluminum and 644 grams of black iron oxide yields about 2368 kJoules of heat. This is far more than required to adequately destroy the hard drive, a smaller amount can also be effectively used to destroy the platters. img6.jpg Using Thermite Using thermite to destroy a hard drive is a very violent and destructive process. Great care should be taken as the molten metal can splash and sputter for a long distance. This is by far a guaranteed method of destroying data in a time of need. We’re pretty sure this will prevent most forensic data recovery methods. img7.jpg img8.jpg End result The reaction takes just a few seconds to complete, and can be controlled using liquid Nitrogen. Finally, if you want to try it, try at your own risk! img9.jpg