Entries Tagged "data destruction"

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Media Sanitization and Encryption

Last week NIST released Special Publication 800-88, Guidelines for Media Sanitization.

There is a new paragraph in this document (page 7) that was not in the draft version:

Encryption is not a generally accepted means of sanitization. The increasing power of computers decreases the time needed to crack cipher text and therefore the inability to recover the encrypted data can not be assured.

I have to admit that this doesn’t make any sense to me. If the encryption is done properly, and if the key is properly chosen, then erasing the key—and all copies—is equivalent to erasing the files. And if you’re using full-disk encryption, then erasing the key is equivalent to sanitizing the drive. For that not to be true means that the encryption program isn’t secure.

I think NIST is just confused.

Posted on September 11, 2006 at 11:43 AM • View Comments

Recovering Data from Cell Phones

People sell, give away, and throw away their cell phones without even thinking about the data still on them:

A company, Trust Digital of McLean, Virginia, bought 10 different phones on eBay this summer to test phone-security tools it sells for businesses. The phones all were fairly sophisticated models capable of working with corporate e-mail systems.

Curious software experts at Trust Digital resurrected information on nearly all the used phones, including the racy exchanges between guarded lovers.

The other phones contained:

  • One company’s plans to win a multimillion-dollar federal transportation contract.
  • E-mails about another firm’s $50,000 payment for a software license.
  • Bank accounts and passwords.
  • Details of prescriptions and receipts for one worker’s utility payments.

The recovered information was equal to 27,000 pages—a stack of printouts 8 feet high.

“We found just a mountain of personal and corporate data,” said Nick Magliato, Trust Digital’s chief executive.

In many cases, this was data that the owners erased.

A popular practice among sellers, resetting the phone, often means sensitive information appears to have been erased. But it can be resurrected using specialized yet inexpensive software found on the Internet.

More and more, our data is not really under our control. We store it on devices and third-party websites, or on our own computer. We try to erase it, but we really can’t. We try to control its dissemination, but it’s harder and harder.

Posted on September 5, 2006 at 9:38 AM •

Privacy Risks of Used Cell Phones

Ignore the corporate sleaziness by Cingular for the moment—they sold used cell phones meant for charity—and focus on the privacy implications. Cingular didn’t erase any of the personal information on the used phones they sold.

This reminds me of Simson Garfinkel’s analysis of used hard drives. He found that 90% of them contained old data, some of it very private and interesting.

Erasing data is one of the big problems of the information age. We know how to do it, but it takes time and we mostly don’t bother. And sadly, these kinds of privacy violations are more the norm than the exception. I don’t think it will get better unless Cingular becomes liable for violating its customers’ privacy like that.

EDITED TO ADD: I already wrote about the risks of losing small portable devices.

Posted on August 26, 2005 at 2:58 PM • View Comments

Secure Flight News

According to Wired News, the DHS is looking for someone in Congress to sponsor a bill that eliminates congressional oversight over the Secure Flight program.

The bill would allow them to go ahead with the program regardless of GAO’s assessment. (Current law requires them to meet ten criteria set by Congress; the most recent GAO report said that they did not meet nine of them.) The bill would allow them to use commercial data even though they have not demonstrated its effectiveness. (The DHS funding bill passed by both the House and the Senate prohibits them from using commercial data during passenger screening, because there has been absolutely no test results showing that it is effective.)

In this new bill, all that would be required to go ahead with Secure Flight would be for Secretary Chertoff to say so:

Additionally, the proposed changes would permit Secure Flight to be rolled out to the nation’s airports after Homeland Security chief Michael Chertoff certifies the program will be effective and not overly invasive. The current bill requires independent congressional investigators to make that determination.

Looks like the DHS, being unable to comply with the law, is trying to change it. This is a rogue program that needs to be stopped.

In other news, the TSA has deleted about three million personal records it used for Secure Flight testing. This seems like a good idea, but it prevents people from knowing what data the government had on them—in violation of the Privacy Act.

Civil liberties activist Bill Scannell says it’s difficult to know whether TSA’s decision to destroy records so swiftly is a housecleaning effort or something else.

“Is the TSA just such an incredibly efficient organization that they’re getting rid of things that are no longer needed?” Scannell said. “Or is this a matter of the destruction of evidence?”

Scannell says it’s a fair question to ask in light of revelations that the TSA already violated the Privacy Act last year when it failed to fully disclose the scope of its testing for Secure Flight and its collection of commercial data on individuals.

My previous essay on Secure Flight is here.

Posted on August 15, 2005 at 9:43 AM • View Comments

Sensitive Information on Used Hard Drives

A research team bought over a hundred used hard drives for about a thousand dollars, and found more than half still contained personal and commercially sensitive information—some of it blackmail material.

People have repeated this experiment again and again, in a variety of countries, and the results have been pretty much the same. People don’t understand the risks of throwing away hard drives containing sensitive information.

What struck me about this story was the wide range of dirt they were able to dig up: insurance company records, a school’s file on its children, evidence of an affair, and so on. And although it cost them a grand to get this, they still had a grand’s worth of salable computer hardware at the end of their experiment.

Posted on March 2, 2005 at 9:40 AM • View Comments

Authentication and Expiration

There’s a security problem with many Internet authentication systems that’s never talked about: there’s no way to terminate the authentication.

A couple of months ago, I bought something from an e-commerce site. At the checkout page, I wasn’t able to just type in my credit-card number and make my purchase. Instead, I had to choose a username and password. Usually I don’t like doing that, but in this case I wanted to be able to access my account at a later date. In fact, the password was useful because I needed to return an item I purchased.

Months have passed, and I no longer want an ongoing relationship with the e-commerce site. I don’t want a username and password. I don’t want them to have my credit-card number on file. I’ve received my purchase, I’m happy, and I’m done. But because that username and password have no expiration date associated with them, they never end. It’s not a subscription service, so there’s no mechanism to sever the relationship. I will have access to that e-commerce site for as long as it remembers that username and password.

In other words, I am liable for that account forever.

Traditionally, passwords have indicated an ongoing relationship between a user and some computer service. Sometimes it’s a company employee and the company’s servers. Sometimes it’s an account and an ISP. In both cases, both parties want to continue the relationship, so expiring a password and then forcing the user to choose another is a matter of security.

In cases with this ongoing relationship, the security consideration is damage minimization. Nobody wants some bad guy to learn the password, and everyone wants to minimize the amount of damage he can do if he does. Regularly changing your password is a solution to that problem.

This approach works because both sides want it to; they both want to keep the authentication system working correctly, and minimize attacks.

In the case of the e-commerce site, the interests are much more one-sided. The e-commerce site wants me to live in their database forever. They want to market to me, and entice me to come back. They want to sell my information. (This is the kind of information that might be buried in the privacy policy or terms of service, but no one reads those because they’re unreadable. And all bets are off if the company changes hands.)

There’s nothing I can do about this, but a username and password that never expire is another matter entirely. The e-commerce site wants me to establish an account because it increases the chances that I’ll use them again. But I want a way to terminate the business relationship, a way to say: “I am no longer taking responsibility for items purchased using that username and password.”

Near as I can tell, the username and password I typed into that e-commerce site puts my credit card at risk until it expires. If the e-commerce site uses a system that debits amounts from my checking account whenever I place an order, I could be at risk forever. (The US has legal liability limits, but they’re not that useful. According to Regulation E, the electronic transfers regulation, a fraudulent transaction must be reported within two days to cap liability at US$50; within 60 days, it’s capped at $500. Beyond that, you’re out of luck.)

This is wrong. Every e-commerce site should have a way to purchase items without establishing a username and password. I like sites that allow me to make a purchase as a “guest,” without setting up an account.

But just as importantly, every e-commerce site should have a way for customers to terminate their accounts and should allow them to delete their usernames and passwords from the system. It’s okay to market to previous customers. It’s not okay to needlessly put them at financial risk.

This essay also appeared in the Jan/Feb 05 issue of IEEE Security & Privacy.

Posted on February 10, 2005 at 7:55 AM • View Comments

Airline Passenger Profiling

From an anonymous reader who works for the airline industry in the United States:

There are two initiatives in the works, neither of which leaves me feeling very good about privacy rights.

The first is being put together by the TSA and is called the “Secure Flight Initiative.” An initial test of this program was performed recently and involved each airline listed in the document having to send in passenger information (aka PNR data) for every passenger that “completed a successful domestic trip” during June 2004. A sample of some of the fields that were required to be sent: name, address, phone (if available), itinerary, any comments in the PNR record made by airline personnel, credit card number and expiration date, and any changes made to the booking before the actual flight.

This test data was transmitted to the TSA via physical CD. The requirement was that we “encrypt” it using pkzip (or equivalent) before putting it on the CD. We were to then e-mail the password to the Secure Flight Initiative e-mail address. Although this is far from ideal, it is in fact a big step up. The original process was going to have people simply e-mail the above data to the TSA. They claim to have a secure facility where the data is stored.

As far as the TSA’s retention of the data, the only information we have been given is that as soon as the test phase is over, they will securely delete the data. We were given no choice but had to simply take their word for it.

Rollout of the Secure Flight initiative is scheduled for “next year” sometime. They’re going to start with larger carriers and work their way down to the smaller carriers. It hasn’t been formalized (as far as I know) yet as to what data will be required to be transmitted when. My suspicion is that upon flight takeoff, all PNR data for all passengers on board will be required to be sent. At this point, I still have not heard as to what method will be used for data transmission.

There is another initiative being implemented by the Customs and Border Protection, which is part of the Department of Homeland Security. This (unnamed) initiative is essentially the same thing as the Secure Flight program. That’s right—two government agencies are requiring us to transmit the information separately to each of them. So much for information sharing within the government.

Most larger carriers are complying with this directive by simply allowing the CBP access to their records directly within their
reservation systems (often hosted by folks like Sabre, Worldspan, Galileo, etc). Others (such as the airline I work for) are opting to
only transmit the bare requirements without giving direct access to our system. The data is transmitted over a proprietary data network that is used by the airline industry.

There are a couple of differences between the Secure Flight program and the one being instituted by the CBP. The CBP’s program requires that PNR data for all booked passengers be transmitted:

  • 72 hours before flight time
  • 24 hours before flight time
  • 8 hours before flight time
  • and then again immediately after flight departure

The other major difference is that it looks as though there will be a requirement that we operate in a way that allows them to send a request for data for any flight at any time which we must send back in an automated fashion.

Oh, and just as a kick in the pants, the airlines are expected to pay the costs for all these data transmissions (to the tune of several thousand dollars a month).

Posted on December 22, 2004 at 10:06 AM • View Comments

Safe Personal Computing

I am regularly asked what average Internet users can do to ensure their security. My first answer is usually, “Nothing—you’re screwed.”

But that’s not true, and the reality is more complicated. You’re screwed if you do nothing to protect yourself, but there are many things you can do to increase your security on the Internet.

Two years ago, I published a list of PC security recommendations. The idea was to give home users concrete actions they could take to improve security. This is an update of that list: a dozen things you can do to improve your security.

General: Turn off the computer when you’re not using it, especially if you have an “always on” Internet connection.

Laptop security: Keep your laptop with you at all times when not at home; treat it as you would a wallet or purse. Regularly purge unneeded data files from your laptop. The same goes for PDAs. People tend to store more personal data—including passwords and PINs—on PDAs than they do on laptops.

Backups: Back up regularly. Back up to disk, tape or CD-ROM. There’s a lot you can’t defend against; a recent backup will at least let you recover from an attack. Store at least one set of backups off-site (a safe-deposit box is a good place) and at least one set on-site. Remember to destroy old backups. The best way to destroy CD-Rs is to microwave them on high for five seconds. You can also break them in half or run them through better shredders.

Operating systems: If possible, don’t use Microsoft Windows. Buy a Macintosh or use Linux. If you must use Windows, set up Automatic Update so that you automatically receive security patches. And delete the files “command.com” and “cmd.exe.”

Applications: Limit the number of applications on your machine. If you don’t need it, don’t install it. If you no longer need it, uninstall it. Look into one of the free office suites as an alternative to Microsoft Office. Regularly check for updates to the applications you use and install them. Keeping your applications patched is important, but don’t lose sleep over it.

Browsing: Don’t use Microsoft Internet Explorer, period. Limit use of cookies and applets to those few sites that provide services you need. Set your browser to regularly delete cookies. Don’t assume a Web site is what it claims to be, unless you’ve typed in the URL yourself. Make sure the address bar shows the exact address, not a near-miss.

Web sites: Secure Sockets Layer (SSL) encryption does not provide any assurance that the vendor is trustworthy or that its database of customer information is secure.

Think before you do business with a Web site. Limit the financial and personal data you send to Web sites—don’t give out information unless you see a value to you. If you don’t want to give out personal information, lie. Opt out of marketing notices. If the Web site gives you the option of not storing your information for later use, take it. Use a credit card for online purchases, not a debit card.

Passwords: You can’t memorize good enough passwords any more, so don’t bother. For high-security Web sites such as banks, create long random passwords and write them down. Guard them as you would your cash: i.e., store them in your wallet, etc.

Never reuse a password for something you care about. (It’s fine to have a single password for low-security sites, such as for newspaper archive access.) Assume that all PINs can be easily broken and plan accordingly.

Never type a password you care about, such as for a bank account, into a non-SSL encrypted page. If your bank makes it possible to do that, complain to them. When they tell you that it is OK, don’t believe them; they’re wrong.

E-mail : Turn off HTML e-mail. Don’t automatically assume that any e-mail is from the “From” address.

Delete spam without reading it. Don’t open messages with file attachments, unless you know what they contain; immediately delete them. Don’t open cartoons, videos and similar “good for a laugh” files forwarded by your well-meaning friends; again, immediately delete them.

Never click links in e-mail unless you’re sure about the e-mail; copy and paste the link into your browser instead. Don’t use Outlook or Outlook Express. If you must use Microsoft Office, enable macro virus protection; in Office 2000, turn the security level to “high” and don’t trust any received files unless you have to. If you’re using Windows, turn off the “hide file extensions for known file types” option; it lets Trojan horses masquerade as other types of files. Uninstall the Windows Scripting Host if you can get along without it. If you can’t, at least change your file associations, so that script files aren’t automatically sent to the Scripting Host if you double-click them.

Antivirus and anti-spyware software : Use it—either a combined program or two separate programs. Download and install the updates, at least weekly and whenever you read about a new virus in the news. Some antivirus products automatically check for updates. Enable that feature and set it to “daily.”

Firewall : Spend $50 for a Network Address Translator firewall device; it’s likely to be good enough in default mode. On your laptop, use personal firewall software. If you can, hide your IP address. There’s no reason to allow any incoming connections from anybody.

Encryption: Install an e-mail and file encryptor (like PGP). Encrypting all your e-mail or your entire hard drive is unrealistic, but some mail is too sensitive to send in the clear. Similarly, some files on your hard drive are too sensitive to leave unencrypted.

None of the measures I’ve described are foolproof. If the secret police wants to target your data or your communications, no countermeasure on this list will stop them. But these precautions are all good network-hygiene measures, and they’ll make you a more difficult target than the computer next door. And even if you only follow a few basic measures, you’re unlikely to have any problems.

I’m stuck using Microsoft Windows and Office, but I use Opera for Web browsing and Eudora for e-mail. I use Windows Update to automatically get patches and install other patches when I hear about them. My antivirus software updates itself regularly. I keep my computer relatively clean and delete applications that I don’t need. I’m diligent about backing up my data and about storing data files that are no longer needed offline.

I’m suspicious to the point of near-paranoia about e-mail attachments and Web sites. I delete cookies and spyware. I watch URLs to make sure I know where I am, and I don’t trust unsolicited e-mails. I don’t care about low-security passwords, but try to have good passwords for accounts that involve money. I still don’t do Internet banking. I have my firewall set to deny all incoming connections. And I turn my computer off when I’m not using it.

That’s basically it. Really, it’s not that hard. The hardest part is developing an intuition about e-mail and Web sites. But that just takes experience.

This essay previously appeared on CNet

Posted on December 13, 2004 at 9:59 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.