February, 2009

Use This Little Known Tool to Securely Delete Files and Folders on Your Hard Drive

For those who grew up with the graphical user interface, command line tools are often seen as arcane remnants from the dawn of PC history, a time when badly-dressed nerds sporting horn-rimmed glasses and pocket protectors ruled the universe (well, maybe just the computer lab). For them, nearly all of the command line tools are little known; for us dinosaurs who were typing on terminals well before the PC arrived, there are few of these older tools we haven’t seen. However, as the GUI gradually replaced the command line and we command line geeks began to point and click more and more, some useful tools escaped our notice. One of these is the ten-year-old SDelete by Mark Russinovich of Sysinternals fame. Microsoft acquired Sysinternals in July, 2006 and made all of the excellent tools available free.

Using SDelete

SDelete is a command line utility that takes a number of options. In any given use, it allows you to delete one or more files and/or directories, or to cleanse the free space on a logical disk. SDelete accepts wild card characters as part of the directory or file specifier.

Usage: sdelete [-p passes] [-s] [-q] <file or directory>
sdelete [-p passes] [-z|-c] [drive letter]

-c     Zero free space (good for virtual disk optimization).

-p passes     Specifies number of overwrite passes.

-s     Recurse subdirectories.

-q     Don’t print errors (quiet).

-z     Cleanse free space.

SDelete implements the Department of Defense clearing and sanitizing standard DOD 5220.22-M, which is overkill (see The Great Drive Wiping Controversy Settled at Last), but ensures your data is deleted forever. There is one caveat: SDelete securely deletes file data, but not file names located in free disk space. If you want to be completely sure that all traces of a file are gone, be sure to use the –c or –z option.

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Want to see even more useful, little known tools? Check out Sysinternals Live:

Sysinternals Live is a service that enables you to execute Sysinternals tools directly from the Web without hunting for and manually downloading them. Simply enter a tool’s Sysinternals Live path into Windows Explorer or a command prompt as http://live.sysinternals.com/<toolnam…; or  \\live.sysinternals.com\tools\<toolname>.

You can view the entire Sysinternals Live tools directory in a browser at http://live.sysinternals.com.

Beware the Phone Phishing Scam

In my area, there has been a rash of phishing calls targeting bank customers. Coincidentally, today’s WXP News (Vol. 8, #59 - Feb 24, 2009 - Issue #367) addresses the same issue:

You might never click a link in an email purporting to be from your bank, but what if someone from the bank called you on the phone and informed you that your account may have been compromised, and asked for your credentials? The best of these scammers will express concern for “security” and insist that you call them back to “verify” that the call is legitimate. And of course, the number that they give you to call is answered with the bank’s name. Some even go so far as to spoof the caller ID information so your phone displays the name of the bank when they call.

The countermeasure to this is to hang up, dial the bank’s main, published phone number and ask to speak to someone in their security department (some banks call it their “Bank Protection” section). Tell them you believe you may be the target of fraudulent activity. Most banks adhere to some variation of this policy: [XYZ Bank] does not contact customers via email, phone or mail to request or verify security information about passwords, personal identification numbers (PINs), credit card numbers or Social Security numbers.

Check your bank’s website for more information and current security alerts. And don’t give out any information over the phone unless you are absolutely sure who is on the other end.

Scareware – Yes, People Do Fall for the Ruse

What happens when people fall for the scareware ruse and actually install the stuff? Oddly enough, they may not even know they’ve been duped. Their systems may run a little slower, but they may be fooled into thinking they’re now being protected by the malware they’ve installed. What follows is a real-life example of someone who wrote in to a well-known security forum. (So as not to cause embarrassment to the victim, I have changed names and details.)

Question one, [Miss K] is very upset that Microsoft uninstalled her new antivirus program.  [Gentlemen], she writes, “I turned on my computer a few days ago, and I got a message saying that Microsoft MSRT had removed AV 2009 from my computer.  So now I don’t have an antivirus installed.  I tried to download another copy of AV 2009, but I couldn’t remember where I got it.  Can you tell me…” [the gentleman reading this question actually thinks it’s a joke] “Can you tell me where to find it, or recommend a free AV program?”

Here is some of the conversation between the hosts:

Host1:  And a lot of people have been getting it.  And MSRT has been removing it from a lot of machines.  So in case [Miss K] is serious, we’re not laughing at you, we’re laughing with you.

Host2:  Yes, because you’re not alone.  There are many, many, many people who’ve fallen for this.  I get - literally I get this call on the radio show all the time.

Host1:  Yes.  Yes.  So do not go looking for another copy of it.  Actually it’ll probably find you, without you having to look for it, and happily crawl into your computer.  It is malicious.  It’s good that Microsoft MSRT removed it.

Scareware–Using Fear & Deception to Dupe Consumers

You’re checking out your favorite web sites when out of the blue a scary message appears on your desktop, which may look like the picture below, or it may just be a box that says “Warning! Spyware detected on your computer!”

What do you do? If you’re the average computer user, this will probably scare you (which is why it’s called “scareware”). You’ll be very tempted to click on the button, thinking that you are ridding yourself of some nasty spyware, but don’t do it: The message is a fake and you’re not really infected. If you click, however, you are going to get infected by some really nasty stuff.

Not only that, but clicking will probably bring up a “registration” screen and if you click on that, you’ll be taken to a web site where the crooks try to sell you their bogus–and totally useless–”security” software. Not only will they dupe you out of $39.95, $49.95, or whatever they’re charging, they’ll get your credit card or banking information and maybe clean you out for real. It’s all a scam and the criminals who run these things are making millions.

The only defense is knowing that these scams exist and not falling for the ruse if you’re ever hit by one. With that in mind–and with some help from various sources on the web–I present a list of some of the more prominent “scareware” scams. This list is by no means complete; new variations appear regularly. But all of them use the same tactic: scare the victim into taking some action.

• AntiVirus 2008, 2009 and 2010: The above screenshots are of Antivirus 2009, but all three are basically the same program and have similar appearance.
• AntiVirus Plus: Sometimes uses Microsoft Security Center alerts to trick you into thinking it’s legit. The screen shot below is totally bogus.

• AntispywareXP 2009: Very intrusive. The fake alerts and scan results overload your system and slow it down.
• XP Antispyware 2009: Virtually the same as AntispywareXP 2009.
• WinDefender 2009: This little gem will always find malware on your system. Of course, what it finds is bogus, but it’ll scare you enough to dupe you into buying the software.
• Personal Defender 2000: Uses the same tactic as WinDefender 2009, but gives a warning about your firewall and then tries to get you to buy the software.
• AntiVirus Sentry: This is one that will often download itself even if you don’t click on anything.
• Security 2009: The crooks responsible for this one have the audacity to advertise it on the Web as if it’s a legitimate application.
• ProAntispyware 2009: You might see this one advertised on the Web, too.
• RapidAntiVirus: This one is capable of damaging your system because it identifies legitimate system files as malware. If you remove the files, you can crash your PC.
• Antispyware 3000: Usually budled with Trojan Horse programs. Looks legit, but don’t let it’s slick appearance fool you–it’s bogus.

Thanks to Redmond Magazine, bleepingcomputer.com, Microsoft Malware Protection Center, and others for information used to compose this post.

There is no "Super Secure" Browser

Security is a complicated process, leaving many to desire a magic bullet. Unfortunately, there isn’t one. No matter how much security developers build into software, the behavior of the person seated in the chair will always be the weak link. Truth be told, all of the major browsers are safer than the browsing habits of their users. I have advocated safe computing practices for years, especially when it comes to keeping operating systems and applications patched. Sure enough, the best protection against malware is a fully patched system.

Recently, Roger A. Grimes of InfoWorld posted “Browser Security Wars” in his Security Advisor blog. For several months, Grimes tested the five most popular Web browsers: Chrome, Firefox, Internet Explorer, Opera, and Safari. His conclusion is no surprise:

So which one is guaranteed to make your Internet browsing experience perfectly safe?

None, of course. If you have the need for high security on a computer you manage, don’t allow it to surf on the public Web. It’s that simple. Internet browsers are highly complex pieces of software interacting with millions of combinations of highly complex active content and programming code, much of it not so friendly. There is no “super secure” browser.

Not exactly a great revelation; however, there is one surprising discovery: In Grimes’s testing, none of the browsers allowed malware to silently install as long as they were running on fully patched systems. Instead, most of them relied on tricking the user into intentionally running an infected executable:

Almost all the malicious Web sites I came across offered an executable to install, usually in the form of bogus anti-malware software or some sort of content player. In order to be infected, I had to intentionally run the offered executable — not always, but nearly so. There was a smattering of sites that tried to use malformed or mismatched content to trick the third-party software into silently executing code, but it was uncommon; and when my system was fully patched, it never silently succeeded. [Emphasis added]

You’ll find a comprehensive rundown of security features and faults of all the aforementioned browsers in InfoWorld’s special report, “InfoWorld Test Center’s guide to browser security.”

Software for Secure Computing: Easy Email & File Security with AxCrypt

Most of the email we send and receive from our co-workers, family, and businesses contains little that requires any degree of confidentiality. The same goes for most of the files we have stored on our hard drives and thumb drives. Occasionally, however, we need to pass on or store some information that wouldn’t be prudent for us to send or store in clear text, i.e., unencrypted. To go through all of the effort (and it’s a bit of effort, believe me) to set up secure email or create encrypted partitions or directories on the hard drive is a waste of time for most people. Fortunately, there’s a simple, free solution: AxCrypt.

AxCrypt is open source file encryption software for Windows. It integrates seamlessly with Windows to encrypt, decrypt, store, send and work with individual files. It runs on Windows 2000/2003/XP/Vista and uses AES-128 encryption.

Once installed, AxCrypt is integrated into Windows Explorer’s context menu. You simply right-click files and folders in Windows Explorer, select AxCrypt and then select the action you want from the sub-menu (see screen shot). If you choose Encrypt Copy to .EXE, AxCrypt makes a copy of the document, asks you for a passphrase, and creates a standalone, self-decrypting file that you can safely send across the network or store anywhere you choose.

To use AxCrypt for secure email, simply create a text file that contains all of the sensitive information you want to send, make a self-decrypting EXE file, and send it as an attachment. You’ll have to make contact with the recipient off-line to give them the passphrase, but your information will be secure in transit.

The AxCrypt site has plenty of information on how to use the program, as well as an excellent FAQ and command line reference.

Check it out. It’s a great addition to your secure computing software collection.

OpenDNS Service to Track and Block Conficker Worm

With some estimates placing the number of computers infected by the Conficker worm at 10 million or more, Conficker has the potential to become one of the biggest botnets ever. Given that many system administrators probably don’t realize they’re hosting the parasite, it’s a good bet that things will get worse before they get better. Fortunately, the good guys at OpenDNS are offering a free service designed to alert administrators of Conficker’s presence and help them with containment and cleanup.

Though Conficker began spreading late last year, so far none of the infected machines has downloaded any software that would create a botnet or send spam. However, that could change in a blink if the criminals behind Conficker add a malicious payload to any of the domains the drones connect to every day. If a network has any PCs that try to connect to the rogue servers, OpenDNS will pinpoint them. As part of the service, infected machines will be prevented from connecting to the control servers:

What’s interesting about this particular virus is that it uses the Domain Name System in a unique way: Conficker contains an algorithm that checks 250 new domains per day for instructions on what it should do. This puts us in a unique position to keep you safe since we’re in the unique position of providing insight and intelligence into your DNS service. We’ve teamed with Kaspersky Lab to identify those 250 daily domains, and stop resolving them.

Administrators must register for a free account in order to take advantage of the service and must use OpenDNS on their networks. Once the account is set up, it’s a simple matter to check for Conficker’s presence:

To find out if Conficker has penetrated your network, simply log in to your account and select Stats on the left sidebar. From there choose Blocked Domains and filter “only domains blocked as malware.” This will generate a list of malware sites your network has attempted to connect with.

Are Windows PCs Threatened by Malware Harbored on Mac & Linux OS’s?

Can Mac and Linux boxes harbor malware that does not affect them, but could affect Windows PCs?  Absolutely. It can and does happen. The Sophos white paper, “Protecting Mac and Linux computers: genuine need or nice to have?” presents a convincing case, describing just how Mac and UNIX/Linux machines threaten Windows PCs.

…it is very common for Windows networks to include a server running UNIX or Linux. Vulnerabilities, such as a weak SSH password, can allow hackers to convert a Linux server into a botnet controller, and install malware that will compromise desktop Windows computers.

Well, that’s one way, but consider this: Viruses, worms, and other types of malware are files, and can be stored on any digital media, regardless of the format or operating system that created them. A Mac/UNIX/Linux machine can store Windows files; a Windows machine can store Mac/UNIX/Linux files. That a Windows virus cannot damage a Mac/UNIX/Linux machine–and vice-versa–is irrelevant: Typhoid Mary harbored and transmitted typhoid fever yet never succumbed to it. She did, however, infect 47 others, three of whom died.

…computers harboring the malware can quietly transmit it to Windows computers. For example, UNIX computers can easily transmit the virus to Windows computers via the Samba fle-sharing system.

If you have a mixed network, it’s time to put some effort into protecting the non-Windows machines. Best practice now dictates that every server and desktop machine in your network be protected with some sort of anti-malware application.