Showing posts with label protecting. Show all posts
Showing posts with label protecting. Show all posts
Thursday, April 27, 2017
Protecting data in the cloud
Protecting data in the cloud
A new hardware design makes data encryption more secure by disguising cloud servers’ memory-access patterns.
But it also raises privacy concerns. A bank of cloud servers could be running applications for 1,000 customers at once; unbeknownst to the hosting service, one of those applications might have no purpose other than spying on the other 999.
Encryption could make cloud servers more secure. Only when the data is actually being processed would it be decrypted; the results of any computations would be re-encrypted before they’re sent off-chip.
In the last 10 years or so, however, it’s become clear that even when a computer is handling encrypted data, its memory-access patterns — the frequency with which it stores and accesses data at different memory addresses — can betray a shocking amount of private information.
At the International Symposium on Computer Architecture in June, MIT researchers described a new type of secure hardware component, dubbed Ascend, that would disguise a server’s memory-access patterns, making it impossible for an attacker to infer anything about the data being stored. Ascend also thwarts another type of attack, known as a timing attack, which attempts to infer information from the amount of time that computations take.
Computational trade-off
Similar designs have been proposed in the past, but they’ve generally traded too much computational overhead for security. “This is the first time that any hardware design has been proposed — it hasn’t been built yet — that would give you this level of security while only having about a factor of three or four overhead in performance,” says Srini Devadas, the Edwin Sibley Webster Professor of Electrical Engineering and Computer Science, whose group developed the new system. “People would have thought it would be a factor of 100.”
The “trivial way” of obscuring memory-access patterns, Devadas explains, would be to request data from every address in the memory — whether a memory chip or a hard drive — and throw out everything except the data stored at the one address of interest. But that would be much too time-consuming to be practical.
What Devadas and his collaborators — graduate students Ling Ren, Xiangyao Yu and Christopher Fletcher, and research scientist Marten van Dijk — do instead is to arrange memory addresses in a data structure known as a “tree.” A family tree is a familiar example of a tree, in which each “node” (in this example, a person’s name) is attached to only one node above it (the node representing the person’s parents) but may connect to several nodes below it (the person’s children).
With Ascend, addresses are assigned to nodes randomly. Every node lies along some “path,” or route through the tree, that starts at the top and passes from node to node, without backtracking, until arriving at a node with no further connections. When the processor requires data from a particular address, it sends requests to all the addresses in a path that includes the one it’s really after.
To prevent an attacker from inferring anything from sequences of memory access, every time Ascend accesses a particular memory address, it randomly swaps that address with one stored somewhere else in the tree. As a consequence, accessing a single address multiple times will very rarely require traversing the same path.
Less computation to disguise an address
By confining its dummy requests to a single path, rather than sending them to every address in memory, Ascend exponentially reduces the amount of computation required to disguise an address. In a separate paper, which is as-yet unpublished but has been posted online, the researchers prove that querying paths provides just as much security as querying every address in memory would.
Ascend also protects against timing attacks. Suppose that the computation being outsourced to the cloud is the mammoth task of comparing a surveillance photo of a criminal suspect to random photos on the Web. The surveillance photo itself would be encrypted, and thus secure from prying eyes. But spyware in the cloud could still deduce what public photos it was being compared to. And the time the comparisons take could indicate something about the source photos: Photos of obviously different people could be easy to rule out, but photos of very similar people might take longer to distinguish.
So Ascend’s memory-access scheme has one final wrinkle: It sends requests to memory at regular intervals — even when the processor is busy and requires no new data. That way, attackers can’t tell how long any given computation is taking.
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Monday, November 7, 2016
Protecting Your Computer from Viruses
Protecting Your Computer from Viruses
- System Health
As everyone who has ever had the flu knows, viruses can be devastating—and computers dont get off any easier than people. Even though a flu virus and a computer virus have obvious differences, there are some similarities: Both you and your computer get viruses from others who are already infected, and prevention can help keep both of you healthy.
Keep in mind that the steps listed in this article are only recommendations that may help prevent virus infection and help deal with it if one does occur. This topic is complex, and it changes rapidly, so its important to stay vigilant and stay informed.
Prevention is the key.
Your best defense is to keep your system from getting infected in the first place because once it is, it can be very difficult, if not impossible, to get rid of the virus. The road to prevention begins with these steps:
- Install effective anti-virus software. Anti-virus software is widely available; any online or brick-and-mortar store that sells software will offer a number of products. These products typically require an annual subscription, which lets you keep your anti-virus software up to date and ready to detect the latest threats.
Tip: For added protection, consider buying a security suite that includes firewall software and other protection (such as spam filtering). - Avoid risky behavior. For example: never open an email attachment that comes from someone you dont know, and avoid downloading anything from the Internet that might not be trustworthy. Keep in mind that humorous material is often passed along, from address to address, through email. Its best not to open this type of file, because even if the attachment is from someone you know, they may be unknowingly passing along a virus.
Make regular virus scans a habit.
Anti-virus software typically lets you choose whether to schedule a scan on a regular basis or perform a manual scan. Because a full scan can take an hour or more to complete, many anti-virus software packages also let you perform a quick, but less thorough, scan of the most commonly infected parts of the computer. See your product documentation for details.
Tip: While you shouldnt depend on it for your main anti-virus solution, another option is to use a free online service to scan your computer, like Trend Micro HouseCall* or Symantec Security Check*.
Youve discovered an infection. Now what?
If you discover a virus or related threat during a scan, follow these steps:
- Follow your anti-virus softwares on-screen instructions. Many viruses can be easily removed using this method. Another option for Windows-based systems is to use the Microsoft Windows Malicious Software Removal Tool*, free software distributed through Windows Update* and updated monthly. Re-scan your computer after youve removed the virus (just to be sure).
Tip: Its also a good idea to scan again with a separate scanner, such as an online service, for added assurance. - Contact an expert. If first efforts arent enough, check your anti-virus products Web site for additional information. Sometimes—especially for high-profile threats—major anti-virus software manufacturers will provide a tool to help get rid of specific viruses. However, these tools can be complicated to use, so depending on how comfortable you are with the procedure, you might want to bring in an expert. Many large retail chains now provide in-store services that specialize in removing viruses. The cost involved can be a small amount to pay to resolve the problem.
- Use restore disks or re-install the operating system. A new computer often comes with a set of one or more emergency "restore" disks. If you havent been able to remove the virus, this set of disks might help you to resolve the problem. However, you will lose any files that havent been backed up on separate media. Although many anti-virus programs let you make a set of emergency restore disks when you install the software. Similarly, if your computer came with a set of one or more operating system disks, you can re-install the operating system and return the computer to factory condition. These options are strong medicine, but if everything else fails, they may be the only way to restore your computers health.
Keeping virus-free
- Install anti-virus software and keep it up to date
- Dont open suspicious email attachments or download untrustworthy Internet content
- Set Windows Update to automatic mode
- Use firewall software
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