Dear Readers,
Here is some information on C-4 explosives:
Twenty years ago, most people didn't have any idea what C-4 was. Recently, it has become an all-too-familiar term, popping up in newspapers and on television all the time. In October 2000, terrorists used C-4 to attack the U.S.S. Cole, killing 17 sailors. In 1996, terrorists used C-4 to blow up the Khobar Towers U.S. military housing complex in Saudi Arabia. In December 2001, a man smuggled similar material, hidden in his shoes, onto a commercial airliner. C-4 has also been used in many of the Palestinian suicide bombings in Israel and the Israeli-occupied territories.
In this article, we'll find out what this powerful material is and see how it can wreak such destruction.
Basics of explosive:
The fundamental concept behind explosives is very simple. At the most basic level, an explosive is just something that burns or decomposes very quickly, producing a lot of heat and gas in a short amount of time.
Photo courtesy U.S. Department of DefenseSoldiers set off two C-4 charges on an air base runway during a training operation. Like other high explosives, C-4's destructive power comes from rapidly expanding hot gas.
A typical explosive consists of some explosive material, some sort of detonation device and, typically, some sort of housing. The explosive material undergoes a rapid chemical reaction, either a combustion or decomposition reaction, when triggered by heat or shock energy from the detonator.
In the chemical reaction, compounds break down to form various gases. The reactants (the original chemical compounds) have a lot of energy stored up as chemical bonds between different atoms. When the compound molecules break apart, the products (the resulting gases) may use some of this energy to form new bonds, but not all of it. Most of the "leftover" energy takes the form of extreme heat.
The concentrated gases are under very high pressure, so they expand rapidly. The heat speeds up the individual gas particles, boosting the pressure even higher. In a high explosive, the gas pressure is strong enough to destroy structures and injure and kill people. If the gas expands faster than the speed of sound, it generates a powerful shock wave. The pressure can also push pieces of solid material outward at great speed, causing them to hit people or structures with a lot of force.
C-4 is a high explosive designed for military use. In the next section, we'll find out what sets it apart from other explosives.
High and Low
In low explosives, such as the propellant in a bullet cartridge, the reaction occurs relatively slowly and the pressure isn't as damaging. The expanding gases only serve to push a small object. High explosives, such as C-4 and TNT, expand more rapidly, generating much greater pressure. Explosives experts refer to rapid explosive reactions as detonation and slower explosive reactions as deflagration.
What is C-4?
C-4, or composition 4, is one variety of plastic explosive. The basic idea of plastic explosives, also called plastic bonded explosives (PBX), is to combine explosive chemicals with a plastic binder material. The binder has two important jobs:
It coats the explosive material, so it's less sensitive to shock and heat. This makes it relatively safe to handle the explosive.
It makes the explosive material highly malleable. You can mold it into different shapes to change the direction of the explosion.
C-4 Ingredients
RDX - 91 percent
Di(2-ethylhexyl) sebacate - 5.3 percent
Polyisobutylene - 2.1 percent
Motor oil - 1.6 percent
The explosive material in C-4 is cyclotrimethylene-trinitramine (C3H6N6O6), commonly called RDX (which stands for "royal demolition explosive" or "research development explosive"). The additive material is made up of polyisobutylene, the binder, and di(2-ethylhexyl) sebacate, the plasticizer (the element that makes the material malleable). It also contains a small amount of motor oil and some 2, 3-dimethyl-2, 3-dinitrobutane (DMDNB), which functions as a chemical marker for security forces.
To make C-4 blocks, explosives manufacturers take RDX in powder form and mix it with water to form a slurry. They then add the binder material, dissolved in a solvent, and mix the materials with an agitator. They remove the solvent through distillation, and remove the water through drying and filtering. The result is a relatively stable, solid explosive with a consistency similar to modelling clay.
Just as with other explosives, you need to apply some energy to C-4 to kick off the chemical reaction. Because of the stabilizer elements, it takes a considerable shock to set off this reaction; lighting the C-4 with a match will just make it burn slowly, like a piece of wood (in Vietnam, soldiers actually burned C-4 as an improvised cooking fire). Even shooting the explosive with a rifle won't trigger the reaction. Only a detonator, or blasting cap will do the job properly.
Photo courtesy U.S. Department of DefenseA U.S. Army unit detonated C-4 explosives inside this Serbian battle tank during Operation Joint Guard.
A detonator is just a smaller explosive that's relatively easy to set off. An electrical detonator, for example, uses a brief charge to set off a small amount of explosive material. When somebody triggers the detonator (by transmitting the charge through detonator cord to a blasting cap, for example), the explosion applies a powerful shock that triggers the C-4 explosive material.
When the chemical reaction begins, the C-4 decomposes to release a variety of gases (notably, nitrogen and carbon oxides). The gases initially expand at about 26,400 feet per second (8,050 meters per second), applying a huge amount of force to everything in the surrounding area. At this expansion rate, it is totally impossible to outrun the explosion like they do in dozens of action movies. To the observer, the explosion is nearly instantaneous -- one second, everything's normal, and the next it's totally destroyed.
The explosion actually has two phases. The initial expansion inflicts most of the damage. It also creates a very low-pressure area around the explosion's origin -- the gases are moving outward so rapidly that they suck most of the gas out from the "middle" of the explosion. After the outward blast, gases rush back in to the partial vacuum, creating a second, less-destructive inward energy wave.
A small amount of C-4 packs a pretty big punch. Less than a pound of C-4 could potentially kill several people, and several military issue M112 blocks of C-4, weighing about 1.25 pounds (half a kilogram) each, could potentially demolish a truck. Demolition experts typically use a good amount of C-4 in order to do a job properly. To take out one 8-inch (20.3-centimeter) square steel beam, for example, they would probably use 8 to 10 pounds (3.6 to 4.5 kilograms) of C-4.
People apply C-4's explosive power toward all kinds of destruction. One common application is military demolition -- soldiers pack it into cracks and crevices to blow up heavy walls. It has also been widely used as an anti-personnel weapon, in battle and in terrorist attacks. In Vietnam, for example, soldiers used a number of C-4-based bombs and grenades. One notable weapon, the claymore mine, consisted of a C-4 block with several embedded ball bearings. When the C-4 was detonated, the ball bearings became deadly flying shrapnel (this sort of weapon was also featured in the movie Swordfish).
Unfortunately, C-4 will keep making headlines for years to come. Because of its stability and sheer destructive power, C-4 has attracted the attention of terrorists and guerilla fighters all over the world. A small amount of C-4 can do a lot of damage, and it's fairly easy to smuggle the explosive past light security forces. The U.S. military is the primary manufacturer of C-4, and it tightly guards its supply, but there are a number of other sources for similar explosive material (including Iran, which has a history of conflict with the United States). As long as it is readily accessible, C-4 will continue to be a primary weapon in the terrorist arsenal.
Source:
www.howstuffworks.com
Thursday, June 28, 2007
Monday, June 25, 2007
Dear readers,
Hope would have enjoyed the last information on NASA.Here is some new information on mobile viruses:
The first known cell-phone virus appeared in 2004 and didn't get very far. Cabir.A infected only a small number of Bluetooth-enabled phones and carried out no malicious action -- a group of malware developers created Cabir to prove it could be done. Their next step was to send it to anti-virus researchers, who began the process of developing a solution to a problem that promises to get a lot worse.
Cell-phone viruses are at the threshold of their effectiveness. At present, they can't spread very far and they don't do much damage, but the future might see cell-phone bugs that are as debilitating as computer viruses. In this article, we'll talk about how cell-phone viruses spread, what they can do and how you can protect your phone from current and future threats.
Basics of mobile virus
A cell-phone virus is basically the same thing as a computer virus -- an unwanted executable file that "infects" a device and then copies itself to other devices. But whereas a computer virus or worm spreads through e-mail attachments and Internet downloads, a cell-phone virus or worm spreads via Internet downloads, MMS (multimedia messaging service) attachments and Bluetooth transfers. The most common type of cell-phone infection right now occurs when a cell phone downloads an infected file from a PC or the Internet, but phone-to-phone viruses are on the rise. Current phone-to-ph
one viruses almost exclusively infect phones running the Symbian operating system. The large number of proprietary operating systems in the cell-phone world is one of the obstacles to mass infection. Cell-phone-virus writers have no Windows-level marketshare to target, so any virus will only affect a small percentage of phones.
Infected files usually show up disguised as applications like games, security patches, add-on functionalities and, of course, pornography and free stuff. Infected text messages sometimes steal the subject line from a message you've received from a friend, which of course increases the likelihood of your opening it -- but opening the message isn't enough to get infected. You have to choose to open the message attachment and agree to install the program, which is another obstacle to mass infection: To date, no reported phone-to-phone virus auto-installs. The installation obstacles and the methods of spreading limit the amount of damage the current generation of cell-phone virus can do.
How they spread?
Phones that can only make and receive calls are not at risk. Only smartphones with a Bluetooth connection and data capabilities can receive a cell-phone virus. These viruses spread primarily in three ways:
Internet downloads - The virus spreads the same way a traditional computer virus does. The user downloads an infected file to the phone by way of a PC or the phone's own Internet connection. This may include file-sharing downloads, applications available from add-on sites (such as ringtones or games) and false security patches posted on the Symbian Web site.
Bluetooth wireless connection - The virus spreads between phones by way of their Bluetooth connection. The user receives a virus via Bluetooth when the phone is in discoverable mode, meaning it can be seen by other Bluetooth-enabled phones. In this case, the virus spreads like an airborne illness. According to TechnologyReview.com, cell-phone-virus researchers at F-Secure's U.S. lab now conduct their studies in a bomb shelter so their research topics don't end up spreading to every Bluetooth-enabled phone in the vicinity.
Multimedia Messaging Service - The virus is an attachment to an MMS text message. As with computer viruses that arrive as e-mail attachments, the user must choose to open the attachment and then install it in order for the virus to infect the phone. Typically, a virus that spreads via MMS gets into the phone's contact list and sends itself to every phone number stored there.
In all of these transfer methods, the user has to agree at least once (and usually twice) to run the infected file. But cell-phone-virus writers get you to open and install their product the same way computer-virus writers do: The virus is typically disguised as a game, security patch or other desirable application.
The Commwarrior virus arrived on the scene in January 2005 and is the first cell-phone virus to effectively spread through an entire company via Bluetooth (see ComputerWorld.com: Phone virus spreads through Scandinavian company). It replicates by way of both Bluetooth and MMS. Once you receive and install the virus, it immediately starts looking for other Bluetooth phones in the vicinity to infect. At the same time, the virus sends infected MMS messages to every phone number in your address list. Commwarrior is probably one of the more effective viruses to date because it uses two methods to replicate itself.
So what does a virus like this do once it infects your phone?
Damage that may occur:
The first known cell-phone virus, Cabir, is entirely innocuous. All it does is sit in the phone and try to spread itself. Other cell-phone viruses, however, are not as harmless.
A virus might access and/or delete all of the contact information and calendar entries in your phone. It might send an infected MMS message to every number in your phone book -- and MMS messages typically cost money to send, so you're actually paying to send a virus to all of your friends, family members and business associates. On the worst-case-scenario end, it might delete or lock up certain phone applications or crash your phone completely so it's useless. Some reported viruses and their vital statistics are listed below.
Cell-phone Viruses
Cabir.AFirst reported: June 2004Attacks: Symbian Series 60 phonesSpreads via: BluetoothHarm: noneMore information (including disinfection): http://www.f-secure.com/v-descs/cabir.shtml
Skulls.AFirst reported: November 2004Attacks: various Symbian phonesSpreads via: Internet downloadHarm: disables all phone functions except sending/receiving callsMore information (including disinfection): http://www.f-secure.com/v-descs/skulls.shtml
Commwarrior.AFirst reported: January 2005Attacks: Symbian Series 60 phonesSpreads via: Bluetooth and MMSHarm: sends out expensive MMS messages to everyone in phonebook (in course of MMS replication)More information (including disinfection): http://www.f-secure.com/v-descs/commwarrior.shtml
Locknut.BFirst reported: March 2005Attacks: Symbian Series 60 phonesSpreads via: Internet download (disguised as patch for Symbian Series 60 phones)Harm: crashes system ROM; disables all phone functions; inserts other (inactive) malware into phoneMore information (including disinfection): http://www.f-secure.com/v-descs/locknut_b.shtml
Fontal.AFirst reported: April 2005Attacks: Symbian Series 60 phonesSpreads via: Internet downloadHarm: locks up phone in startup mode; disables phone entirelyMore information (including disinfection): http://www.f-secure.com/v-descs/fontal_a.shtml
As you can see from the above descriptions, cell-phone viruses have gotten a lot more harmful since the Cabir worm landed in the hands of researchers in 2004. But on the bright side, there are some steps you can take to protect your phone.
Protecting your phone:
The best way to protect yourself from cell-phone viruses is the same way you protect yourself from computer viruses: Never open anything if you don't know what it is, haven't requested it or have any suspicions whatsoever that it's not what it claims to be. That said, even the most cautious person can still end up with an infected phone. Here are some steps you can take to decrease your chances of installing a virus:
Turn off Bluetooth discoverable mode. Set your phone to "hidden" so other phones can't detect it and send it the virus. You can do this on the Bluetooth options screen.
Check security updates to learn about filenames you should keep an eye out for. It's not fool-proof -- the Commwarrior program generates random names for the infected files it sends out, so users can't be warned not to open specific filenames -- but many viruses can be easily identified by the filenames they carry. Security sites with detailed virus information include:
F-Secure
McAfee
Symantec
Some of these sites will send you e-mail updates with new virus information as it gets posted.
Install some type of security software on your phone. Numerous companies are developing security software for cell phones, some for free download, some for user purchase and some intended for cell-phone service providers. The software may simply detect and then remove the virus once it's received and installed, or it may protect your phone from getting certain viruses in the first place. Symbian has developed an anti-virus version of its operating system that only allows the phone's Bluetooth connection to accept secure files.
Although some in the cell-phone industry think the potential problem is overstated, most experts agree that cell-phone viruses are on the brink of their destructive power. Installing a "security patch" that ends up turning your phone into a useless piece of plastic is definitely something to be concerned about, but it could still get worse. Future possibilities include viruses that bug phones -- so someone can see every number you call and listen to your conversations -- and viruses that steal financial information, which would be a serious issue if smartphones end up being used as payment devices (see Bankrate.com: Paying by cell phone on the way). Ultimately, more connectivity means more exposure to viruses and faster spreading of infection. As smartphones become more common and more complex, so will the viruses that target them.
Source:www.howstuffworks.com
Hope would have enjoyed the last information on NASA.Here is some new information on mobile viruses:
The first known cell-phone virus appeared in 2004 and didn't get very far. Cabir.A infected only a small number of Bluetooth-enabled phones and carried out no malicious action -- a group of malware developers created Cabir to prove it could be done. Their next step was to send it to anti-virus researchers, who began the process of developing a solution to a problem that promises to get a lot worse.
Cell-phone viruses are at the threshold of their effectiveness. At present, they can't spread very far and they don't do much damage, but the future might see cell-phone bugs that are as debilitating as computer viruses. In this article, we'll talk about how cell-phone viruses spread, what they can do and how you can protect your phone from current and future threats.
Basics of mobile virus
A cell-phone virus is basically the same thing as a computer virus -- an unwanted executable file that "infects" a device and then copies itself to other devices. But whereas a computer virus or worm spreads through e-mail attachments and Internet downloads, a cell-phone virus or worm spreads via Internet downloads, MMS (multimedia messaging service) attachments and Bluetooth transfers. The most common type of cell-phone infection right now occurs when a cell phone downloads an infected file from a PC or the Internet, but phone-to-phone viruses are on the rise. Current phone-to-ph
one viruses almost exclusively infect phones running the Symbian operating system. The large number of proprietary operating systems in the cell-phone world is one of the obstacles to mass infection. Cell-phone-virus writers have no Windows-level marketshare to target, so any virus will only affect a small percentage of phones.
Infected files usually show up disguised as applications like games, security patches, add-on functionalities and, of course, pornography and free stuff. Infected text messages sometimes steal the subject line from a message you've received from a friend, which of course increases the likelihood of your opening it -- but opening the message isn't enough to get infected. You have to choose to open the message attachment and agree to install the program, which is another obstacle to mass infection: To date, no reported phone-to-phone virus auto-installs. The installation obstacles and the methods of spreading limit the amount of damage the current generation of cell-phone virus can do.
How they spread?
Phones that can only make and receive calls are not at risk. Only smartphones with a Bluetooth connection and data capabilities can receive a cell-phone virus. These viruses spread primarily in three ways:
Internet downloads - The virus spreads the same way a traditional computer virus does. The user downloads an infected file to the phone by way of a PC or the phone's own Internet connection. This may include file-sharing downloads, applications available from add-on sites (such as ringtones or games) and false security patches posted on the Symbian Web site.
Bluetooth wireless connection - The virus spreads between phones by way of their Bluetooth connection. The user receives a virus via Bluetooth when the phone is in discoverable mode, meaning it can be seen by other Bluetooth-enabled phones. In this case, the virus spreads like an airborne illness. According to TechnologyReview.com, cell-phone-virus researchers at F-Secure's U.S. lab now conduct their studies in a bomb shelter so their research topics don't end up spreading to every Bluetooth-enabled phone in the vicinity.
Multimedia Messaging Service - The virus is an attachment to an MMS text message. As with computer viruses that arrive as e-mail attachments, the user must choose to open the attachment and then install it in order for the virus to infect the phone. Typically, a virus that spreads via MMS gets into the phone's contact list and sends itself to every phone number stored there.
In all of these transfer methods, the user has to agree at least once (and usually twice) to run the infected file. But cell-phone-virus writers get you to open and install their product the same way computer-virus writers do: The virus is typically disguised as a game, security patch or other desirable application.
The Commwarrior virus arrived on the scene in January 2005 and is the first cell-phone virus to effectively spread through an entire company via Bluetooth (see ComputerWorld.com: Phone virus spreads through Scandinavian company). It replicates by way of both Bluetooth and MMS. Once you receive and install the virus, it immediately starts looking for other Bluetooth phones in the vicinity to infect. At the same time, the virus sends infected MMS messages to every phone number in your address list. Commwarrior is probably one of the more effective viruses to date because it uses two methods to replicate itself.
So what does a virus like this do once it infects your phone?
Damage that may occur:
The first known cell-phone virus, Cabir, is entirely innocuous. All it does is sit in the phone and try to spread itself. Other cell-phone viruses, however, are not as harmless.
A virus might access and/or delete all of the contact information and calendar entries in your phone. It might send an infected MMS message to every number in your phone book -- and MMS messages typically cost money to send, so you're actually paying to send a virus to all of your friends, family members and business associates. On the worst-case-scenario end, it might delete or lock up certain phone applications or crash your phone completely so it's useless. Some reported viruses and their vital statistics are listed below.
Cell-phone Viruses
Cabir.AFirst reported: June 2004Attacks: Symbian Series 60 phonesSpreads via: BluetoothHarm: noneMore information (including disinfection): http://www.f-secure.com/v-descs/cabir.shtml
Skulls.AFirst reported: November 2004Attacks: various Symbian phonesSpreads via: Internet downloadHarm: disables all phone functions except sending/receiving callsMore information (including disinfection): http://www.f-secure.com/v-descs/skulls.shtml
Commwarrior.AFirst reported: January 2005Attacks: Symbian Series 60 phonesSpreads via: Bluetooth and MMSHarm: sends out expensive MMS messages to everyone in phonebook (in course of MMS replication)More information (including disinfection): http://www.f-secure.com/v-descs/commwarrior.shtml
Locknut.BFirst reported: March 2005Attacks: Symbian Series 60 phonesSpreads via: Internet download (disguised as patch for Symbian Series 60 phones)Harm: crashes system ROM; disables all phone functions; inserts other (inactive) malware into phoneMore information (including disinfection): http://www.f-secure.com/v-descs/locknut_b.shtml
Fontal.AFirst reported: April 2005Attacks: Symbian Series 60 phonesSpreads via: Internet downloadHarm: locks up phone in startup mode; disables phone entirelyMore information (including disinfection): http://www.f-secure.com/v-descs/fontal_a.shtml
As you can see from the above descriptions, cell-phone viruses have gotten a lot more harmful since the Cabir worm landed in the hands of researchers in 2004. But on the bright side, there are some steps you can take to protect your phone.
Protecting your phone:
The best way to protect yourself from cell-phone viruses is the same way you protect yourself from computer viruses: Never open anything if you don't know what it is, haven't requested it or have any suspicions whatsoever that it's not what it claims to be. That said, even the most cautious person can still end up with an infected phone. Here are some steps you can take to decrease your chances of installing a virus:
Turn off Bluetooth discoverable mode. Set your phone to "hidden" so other phones can't detect it and send it the virus. You can do this on the Bluetooth options screen.
Check security updates to learn about filenames you should keep an eye out for. It's not fool-proof -- the Commwarrior program generates random names for the infected files it sends out, so users can't be warned not to open specific filenames -- but many viruses can be easily identified by the filenames they carry. Security sites with detailed virus information include:
F-Secure
McAfee
Symantec
Some of these sites will send you e-mail updates with new virus information as it gets posted.
Install some type of security software on your phone. Numerous companies are developing security software for cell phones, some for free download, some for user purchase and some intended for cell-phone service providers. The software may simply detect and then remove the virus once it's received and installed, or it may protect your phone from getting certain viruses in the first place. Symbian has developed an anti-virus version of its operating system that only allows the phone's Bluetooth connection to accept secure files.
Although some in the cell-phone industry think the potential problem is overstated, most experts agree that cell-phone viruses are on the brink of their destructive power. Installing a "security patch" that ends up turning your phone into a useless piece of plastic is definitely something to be concerned about, but it could still get worse. Future possibilities include viruses that bug phones -- so someone can see every number you call and listen to your conversations -- and viruses that steal financial information, which would be a serious issue if smartphones end up being used as payment devices (see Bankrate.com: Paying by cell phone on the way). Ultimately, more connectivity means more exposure to viruses and faster spreading of infection. As smartphones become more common and more complex, so will the viruses that target them.
Source:www.howstuffworks.com
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