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'Anonymous' hackers target US security think tank

meikana555 | Rabu, 28 Desember 2011 | Labels: , , , , , , , , ,

LONDON (AP) — The loose-knit hacking movement "Anonymous" claimed Sunday to have stolen thousands of credit card numbers and other personal information belonging to clients of U.S.-based security think tank Stratfor. One hacker said the goal was to pilfer funds from individuals' accounts to give away as Christmas donations, and some victims confirmed unauthorized transactions linked to their credit cards.
Anonymous boasted of stealing Stratfor's confidential client list, which includes entities ranging from Apple Inc. to the U.S. Air Force to the Miami Police Department, and mining it for more than 4,000 credit card numbers, passwords and home addresses.
Austin, Texas-based Stratfor provides political, economic and military analysis to help clients reduce risk, according to a description on its YouTube page. It charges subscribers for its reports and analysis, delivered through the web, emails and videos. The company's main website was down, with a banner saying the "site is currently undergoing maintenance."
Proprietary information about the companies and government agencies that subscribe to Stratfor's newsletters did not appear to be at any significant risk, however, with the main threat posed to individual employees who had subscribed.
"Not so private and secret anymore?" Anonymous taunted in a message on Twitter, promising that the attack on Stratfor was just the beginning of a Christmas-inspired assault on a long list of targets.
Anonymous said the client list it had already posted was a small slice of the 200 gigabytes worth of plunder it stole from Stratfor and promised more leaks. It said it was able to get the credit card details in part because Stratfor didn't bother encrypting them — an easy-to-avoid blunder which, if true, would be a major embarrassment for any security-related company.
Fred Burton, Stratfor's vice president of intelligence, said the company had reported the intrusion to law enforcement and was working with them on the investigation.
Stratfor has protections in place meant to prevent such attacks, he said.
"But I think the hackers live in this kind of world where once they fixate on you or try to attack you it's extraordinarily difficult to defend against," Burton said.
Hours after publishing what it claimed was Stratfor's client list, Anonymous tweeted a link to encrypted files online with names, phone numbers, emails, addresses and credit card account details.
"Not as many as you expected? Worry not, fellow pirates and robin hoods. These are just the 'A's," read a message posted online that encouraged readers to download a file of the hacked information.
The attack is "just another in a massive string of breaches we've seen this year and in years past," said Josh Shaul, chief technology officer of Application Security Inc., a New York-based provider of database security software.
Still, companies that shared secret information with Stratfor in order to obtain threat assessments might worry that the information is among the 200 gigabytes of data that Anonymous claims to have stolen, he said.
"If an attacker is walking away with that much email, there might be some very juicy bits of information that they have," Shaul said.
Lt. Col. John Dorrian, public affairs officer for the Air Force, said that "for obvious reasons" the Air Force doesn't discuss specific vulnerabilities, threats or responses to them.
"The Air Force will continue to monitor the situation and, as always, take appropriate action as necessary to protect Air Force networks and information," he said in an email.
Miami Police Department spokesman Sgt. Freddie Cruz Jr. said that he could not confirm that the agency was a client of Stratfor, and he said he had not received any information about a security breach involving the police department.
Anonymous also linked to images online that it suggested were receipts for charitable donations made by the group manipulating the credit card data it stole.
"Thank you! Defense Intelligence Agency," read the text above one image that appeared to show a transaction summary indicating that an agency employee's information was used to donate $250 to a non-profit.
One receipt — to the American Red Cross — had Allen Barr's name on it.
Barr, of Austin, Texas, recently retired from the Texas Department of Banking and said he discovered last Friday that a total of $700 had been spent from his account. Barr, who has spent more than a decade dealing with cybercrime at banks, said five transactions were made in total.
"It was all charities, the Red Cross, CARE, Save the Children. So when the credit card company called my wife she wasn't sure whether I was just donating," said Barr, who wasn't aware until a reporter with the AP called that his information had been compromised when Stratfor's computers were hacked.
"It made me feel terrible. It made my wife feel terrible. We had to close the account."
Wishing everyone a "Merry LulzXMas" — a nod to its spinoff hacking group Lulz Security — Anonymous also posted a link on Twitter to a site containing the email, phone number and credit number of a U.S. Homeland Security employee.
The employee, Cody Sultenfuss, said he had no warning before his details were posted.
"They took money I did not have," he told The Associated Press in a series of emails, which did not specify the amount taken. "I think 'Why me?' I am not rich."
But the breach doesn't necessarily pose a risk to owners of the credit cards. A card user who suspects fraudulent activity on his or her card can contact the credit card company to dispute the charge.
Stratfor said in an email to members, signed by Stratfor Chief Executive George Friedman and passed on to AP by subscribers, that it had hired a "leading identity theft protection and monitoring service" on behalf of the Stratfor members affected by the attack. The company said it will send another email on services for affected members by Wednesday.
Stratfor acknowledged that an "unauthorized party" had revealed personal information and credit card data of some of its members.
The company had sent another email to subscribers earlier in the day saying it had suspended its servers and email after learning that its website had been hacked.
One member of the hacking group, who uses the handle AnonymousAbu on Twitter, claimed that more than 90,000 credit cards from law enforcement, the intelligence community and journalists — "corporate/exec accounts of people like Fox" News — had been hacked and used to "steal a million dollars" and make donations.
It was impossible to verify where credit card details were used. Fox News was not on the excerpted list of Stratfor members posted online, but other media organizations including MSNBC and Al-Jazeera English appeared in the file.
Anonymous warned it has "enough targets lined up to extend the fun fun fun of LulzXmas through the entire next week."
The group has previously claimed responsibility for attacks on credit card companies Visa Inc. and MasterCard Inc., eBay Inc.'s PayPal, as well as other groups in the music industry and the Church of Scientology.
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Plushnick-Masti reported from Houston. Associated Press writers Jennifer Kay in Miami and Daniel Wagner in Washington, D.C. also contributed to this report.
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Important Factors That Influence Enzyme Activity

meikana555 | Rabu, 16 November 2011 | Labels: , , , ,

Enzymes are essential for almost all the chemical reactions that take place inside living cells. However, the activities of the enzymes can be enhanced or inhibited by a number of factors. In this article, we are talking about all those factors that affect enzyme activity.

Enzymes are protein-based complex molecules produced by the cells. There are several enzymes which are involved with different biochemical reactions. Each of these enzymes present in our body can influence any one particular chemical reaction or a set of reactions. They serve as organic catalysts and enhance the speed of the reactions in which they take part. In the absence of an enzyme, the speed of a chemical reaction becomes extremely slow. Some of these reactions may not occur if the right kind of enzyme is not present in the body.

Enzyme Activity Explained

An enzyme can increase the speed of a chemical reaction manifold. You will be surprised to know that studies have found that it can make a chemical reaction 10 billion times faster. The chemical substances that are present at the start of a biochemical process is termed as substrates which undergo chemical change(s) to form one or more end products. Basically, the active site of the enzymes forms a temporary bond with the substrate. During this time, an enzyme lowers the activation energy of the participant molecules which in turn speeds up the reaction. After the reaction is over, the newly formed product leaves the surface of the enzyme and the enzyme gets back its original shape. Thus, you can say it participates in the reaction without undergoing any physical or chemical change. Therefore, the same enzyme is used again and again for the specific process.

Factors Influencing Enzyme Activity

Concentrations of substrate and enzyme have an impact on the activity of the enzymes. Besides, environmental conditions such as temperature, pH values, presence of inhibitors, etc. also influence their activities. Each of these important factors have been discussed below:

Effects of Change in Temperature
All enzymes need a favorable temperature to work properly. The rate of a biochemical reaction increases with rise in temperature. This is because the heat enhances the kinetic energy of the participant molecules which results in more number of collisions between them. On the other hand, it is mostly found that in low temperature conditions, the reaction becomes slow as there is less contact between the substrate and the enzyme. However, extreme temperatures are not good for the enzymes. Under the influence of very high temperature, the enzyme molecule tends to get distorted, due to which the rate of reaction decreases. In other words, a denatured enzyme fails to carry out its normal functions. In the human body, the optimum temperature at which most enzymes become highly active lies in the range of 95 °F to 104 °F (35 °C to 40 °C). There are some enzymes that prefer a lower temperature than this.

Effects of Change in pH Value
The efficiency of an enzyme is largely influenced by the pH value of its surroundings. This is because the charge of its component amino acids changes with the change in the pH value. Each enzyme becomes active at a certain pH level. In general, most enzymes remain stable and work well in the pH range of 6 and 8. However, there are some specific enzymes which work well only in acidic or basic surroundings. The favorable pH value for a specific enzyme actually depends on the biological system in which it is working. When the pH value becomes very high or too low, then the basic structure of the enzyme undergoes change(s). As a result, the active site of the enzyme fails to bind well with the substrate properly and the activity of the enzyme gets badly affected. The enzyme may even stop functioning completely.

Effects of Substrate Concentration
Substrate concentration plays a major role in various enzyme activities. This is obviously because higher concentration of substrate means more number of substrate molecules are involved with the enzyme activity. Whereas, a low concentration of substrate means less number of molecules will get attached to the enzymes. This in turn reduces the enzyme activity. When the rate of an enzymatic reaction is maximum and the enzyme is at its most active state, an increase in the concentration of substrate will not make any difference in the enzyme activity. In this condition, the substrate is continuously replaced by new ones at the active site of the enzyme and there is no scope to add those extra molecules there.

Effects of Enzyme Concentration
In any enzymatic reaction, the quantity of substrate molecules involved is more as compared to the number of enzymes. A rise in enzyme concentration will enhance the enzymatic activity for the simple reason that more enzymes are participating in the reaction. The rate of the reaction is directly proportional to the quantity of enzymes available for it. However, that does not mean that a constant rise in concentration of enzymes will lead to a steady rise in the rate of reaction. Rather, a very high concentration of enzymes where all the substrate molecules are already used up does not have any impact on the reaction rate. To be precise, once the rate of reaction has attained stability, an increase in the quantity of enzymes does not affect the rate of reaction anymore.

Effects of Inhibitors
As the name suggests, inhibitors are those substances that have a tendency to prevent activities of the enzymes. Enzyme inhibitors interfere with the enzyme functions in two different ways. Based on this, they are divided into two categories: competitive inhibitors and noncompetitive inhibitors. A competitive inhibitor has a structure which is the same as that of a substrate molecule, and so it gets attached to the activated center of the enzyme easily and restricts the bond formation of enzyme-substrate complex. A noncompetitive inhibitor is the one which brings about change(s) in the shape of the enzymes by reacting with its active site. In this condition, the substrate molecule cannot bind itself to the enzyme and thus, the subsequent activities are blocked.

Effects of Allosteric Factors
There are some enzymes which have one active site and one or more regulatory sites and are known as allosteric enzymes. A molecule that binds with the regulatory sites are referred to as allosteric factor. When this molecule in the cellular environment forms a weak noncovalent bond at the regulatory site, the shape of the enzyme and its activation center get modified. This change usually decreases the enzyme activity as it inhibits the formation of a new enzyme-substrate complex. However, there are some allosteric activators that promote the affinity between the enzyme and the substrate and influence enzymatic behavior positively.

Hope this article helped you to get an overview about different factors that promote and inhibit the actions of various enzymes present in the living cells. We can conclude from the information provided here that all the enzymes require a favorable condition to function properly. An unfavorable condition tends to influence enzyme activity adversely.
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Published: 11/16/2011
 
 
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