Speed matters. How to make a forensic image as quickly as possible.

The typical method used to create a forensic image is to connect the source disk to a write-blocker. The write-blocker is then connected to a computer and a forensic image is made. This process needs to be updated to keep up with the capacity and speeds of the newest disk drive. By making the process as efficient as possible, the forensic imaging times can be substantially reduced.

When making a forensic image of a disk drive, it is necessary to copy every byte available from the source disk and to ensure that nothing is written to the source disk. As the capacity of disk drives has increased, the time required to make a forensic image has also increased. For example, a 20GB disk drive would take approximately 8 minutes to image at best. A 200GB could take approximately 50 minutes at best, while a 1TB disk drive would take approximately 2.5 hours.

We can calculate how fast a disk drive can be imaged by dividing the total capacity of the disk by the maximum sustained transfer rate (MSTR) of the disk. The MSTR is the manufacturers information on how fast data can be read off of a disk drive for a very large transfer. The MSTR tells us how fast data comes off of the disk. (Note that the maximum burst transfer rate is not of use to us since it only provides information on how quickly data comes out of the disk cache, and it only applies to a small amount of data.)

Let’s look at a 1.5TB Western Digitial Caviar Green disk drive as an example. The data for this drive is available here.  This disk drive has a capacity of 1,500,301 MB and it has a maximum sustained transfer rate of 110 MB/s. Thus, it would take 227.3 minutes (almost 4 hours) to forensically copy the entire contents of the disk drive. (A transfer rate of 110MB/s is 6.6 GB/minute.) To achieve this speed, all parts of the forensic imaging process must be able to process data at a rate of 6.6GB/minute or greater.

Using a USB 2.0 write-blocker would slow this transfer rate down dramatically, as USB 2.0 has a maximum data transfer rate of approximately 34 MB/s. Using a USB 2.0 write-blocker when imaging the 1.5TB disk drive would require 735.4 minutes (over 12 hours).

Other factors that can alter the efficiency of the disk imaging process include:

  • The buffer size of a data transfer.
  • The filesystem where the data is being written to.
  • Whether compression is used when making the forensic image.

All of the above factors need to be tuned to ensure that forensic images are made as quickly and efficiently as possible.

I have recently published a paper in the Journal of Forensic Sciences entitiled Characteristic of Forensic Imaging. This article discusses the impacts of different factors on the efficiency of forensic imaging. I am also preparing a web page that will provide simple scripts to allow you to evaluate the efficiency of your forensic imaging setup.

the latest on credit card frauds

Recently I worked with Acme (the name has been changed to protect their identify), a retail company that had been contacted by their bank. (Let’s call the company Acme.) During an investigation of some credit card frauds, the bank discovered that many of the fraudulent transactions appeared to have one location in common, Acme.

The analysis works like this. Let’s assume that Joe Smith and Mary Jones used their credit cards at Acme on March 1st. Then, on March 20th, both Joe’s and Mary’s credit cards were involved in fraudulent transactions. Once a credit card is involved in a fraudulent transaction, the banks look to see if this transaction is part of a larger fraud. So, they check the historical transactions of Joe and Mary, looking for the business that they both have in common. The theory is simple, if Joe and Mary visited a company with a security breach, it will be seen in the historical analysis.

This type of fraud analysis is useful for detecting when many credit cards are compromised at a business. If the bank can identify the location where credit card numbers were compromised, it can prevent future fraud from that compromise. In order to do that, the bank will need to cancel all credit cards that were used at the business where the compromised occurred and re-issue new ones.

Back to Acme. So, based upon fraud analysis, the bank had strong reason to believe that somehow Acme was leaking credit card numbers. In fact, the bank suspected that over 70 fraudulent transactions resulted from a problem with Acme. Our review of Acme showed that their network was Payment Card Industry (PCI) compliant. The credit card numbers were protected in Acme’s network. So, the card numbers were not leaking out because a network hacker.

This left only two options. The first is that an employee or employees were stealing the credit card numbers through the use of a skimmer, or that Acme’s card processor was hacked. Based upon the fact that only certain transactions at Acme were reported as compromised, this meant that the skimmer possibility was much more likely.

While there has been a lot of work on securing credit card data over the network, the physical credit card is still vulnerable to the skimming attack.

In order to protect yourself, do not let you credit card out of your sight when you use it. Because when it is out of your sight, it is possible that the person that took your credit card also took a copy of your credit card.



Why won’t my call go through? Denial of service in the cell phone network.

Recently, some of the major cellular carriers have released “Network Extenders”, also known as femtocell. The network extender is a device that a subscriber purchases to extend the reach of the cell phone network. (In effect, the subscriber is paying for the privilege of increasing the cellular network coverage. What a deal!)

The network extender is conceptually similar to a Wi-Fi access point. Both connect to the Internet via wire, and both provide wireless services. While the Wi-Fi device provides Internet services, the femtocell provides cellular services.

The femtocell basically appears as a new cell tower to cell phones that are within its range. And, the femtocell will process calls for any and all cell phones that successfully register with the cell phone while is it connected to the Internet. Effectively, the femtocell is just a new gateway to the cellular network.

It is not possible for the cell phone owner to choose to connect to the femtocell or to a regular cell tower. The decision on how the cell phone connects to the cell network is made by the cell phone and the “cell tower”. And, this did not used to be a problem, when only the cellular carriers were putting up cell towers. However, the release of the network extender has allowed individuals to deploy cell towers.

Recently, I encountered a denial of service issue with a cell phone that I tracked back to an issue with a femtocell. A cell phone has registered with the femtocell to connect to the wireless network. However, the femtocell lost connectivity to the Internet. (Remember, the femtocell is a gateway that uses the Internet to connect to the cellular network.)

Since the femtocell still had power, the wireless side was still active. This meant that any cell phone that had registered with the femtocell thought that it was still connected to the cellular network. However, the femtocell had no ability to connect to the cellular network, since the Internet was done. It appears that the current cell phones do not have the ability to determine if they are connected to a cell tower that is active.

Thus, the cell phone could not make or receive calls or text messages. And the user had no ability to tell the cell phone to switch to a working cell tower. The only was to get the cell phone working again was to move to a different area, outside of the range of the femtocell. And, the cell phone reported 3 or 4 bars during the entire outage.

Until the carriers improve the algorithm that a cell phone uses to ensure it has an active cell tower, about the only thing the subscriber can do is use a Voice over IP (VoIP) application as a backup to the standard phone. And, this will only work if the VoIP application can use the Wi-Fi network for calls. And, if that is not possible, use email, which should still work via Wi-Fi if the cell tower is not functioning.


SCADA and security

A recent article  by Hal Hodson of Information Age reports that the FBI has publicly stated that hackers have successfully targeted SCADA systems in three unnamed US communities. The attacks were reported to have the potential to shut down electricity at a nearby mall as well as the potential to dump sewage. Just weeks earlier came an announcement from the Illinois Statewide Terrorism and Intelligence Center that claimed a water pump failure was caused by a hacker attacking the pump control system. The failure came from the attackers repeatedly turning the pump on and off. (The Illinois hacking attack has been refuted the FBI, so then it must not be one of the three sites reported above, right?)

So, what exactly is SCADA? Supervisory Control and Data Acquisition. SCADA systems control power production and distribution, such as those used for the generation of electricity or the delivery of water to communities. They are basically used to support the infrastructure that we rely upon. Thus, the failure of SCADA systems can impact a large number of people.

In a display of the potential damage that can be caused by an attack on the SCADA network , let’s look back to Stuxnet . This malware was reported to have targeted very specific Siemens based SCADA systems. (The attack was so specific that there was speculation that the purpose of the malware was to damage the nuclear facilities of Iran.) While details are hard to come by, it appears that the Stuxnet attack resulted in damage to centrifuges. (The centrifuge is used to separate different isotopes of uranium.)

Stuxnet caused incorrect data to be reported, which lead to the control systems effectively “mis-operating” the equipment. This “mis-operation” then resulted in damage. Stuxnet further revealed that it is difficult to prevent SCADA systems from malware attack. Theoretically, Stuxnet should not have been able to infect the SCADA systems controlling the centrifuges. However, in practice, it did because somehow the malware was introduced, either through an Internet connection or carried in via a USB. This reveals the risks of taking SCADA systems that are already network capable systems and making them accessible via the Internet.

So, you would think that a malware infection such as Stuxnet could not happen again. Not so fast, as Iran has reported that they are now dealing with another virus, the Duqu virus, that is targeting their civil defense system.

Well, what can we learn from all of this? Certainly, virus scanners are less effective now, especially against a determined adversary. Therefore, it truly is important that SCADA systems be shielded from the introduction of malware, whether it is via the Internet or through a USB device.

As consumers, we all have an interest in the security of the SCADA systems that manage our power, our water, and even our prisons.

How to find hidden passwords (and how to protect them)

While preparing to teach a computer forensic workshop, I discovered a new live Linux distribution entitled C.A.IN.E, (Computer Aided Investigative Environment.) This software is one of a few live Linux distributions that allows a user to boot Linux from a CD or DVD and start a forensic investigation. The distribution includes tools to make forensic and analyze forensic images. Since it is freeware, it is easy to make use of the software as part of the workshop.

In addition to Linux tools, NBCAINE version 2.5 includes WinTaylor, a set of tools that are designed to run on a Windows system.This software can be loaded onto a USB through the “dd” utility. (Once loaded on the USB,  a user can boot the live distro off of the USB and not access the WinTaylor tools or plug the USB into a running Windows system and access the WinTaylor tools.) Included in the WinTaylor section of the software are Windows based tools from NirSoft that allow a user to recover passwords saved in popular web browsers, view recent file activity on the Windows system, view information about USB drives attached to the computer and more.

The NirSoft tools include some noteworthy ones that are designed to uncover passwords stored on Windows systems. For example, when you log into a password protected website, Internet Explorer (and other browsers) give you the option to save the login information so that you don’t need to enter it the next time. A Nirsoft utility, iepv.exe(Internet Explorer Password Viewer), retrieves and displays the userids and passwords. If you use Microsoft Outlook and save your POP3 or IMAP password,  the Nirsoft utility mailpv.exe will retrieve and display the accounts and passwords saved in Outlook. And, WirelessKeyView.exe will display the wireless network names and associated passwords that are stored in your system.

I encourage you to obtain these tools and run them on your system to reveal how many passwords are stored on your system. If you discover sensitive passwords stored on your system and you allow others to use your system, you will want to ensure that you clean out the stored passwords.

While you might not be able to delete all of the saved passwords, at least you will now have a better handle on all of the passwords stored on your system that are recoverable.

Revenge Hacking

Revenge is a powerful motivator for hacking. Take, for example, the case of Barry Ardolf of Minnesota. Trouble started when Mr. Ardolf was accused by a neighbor of kissing their 4-year boy on the lips. When the parents confronted Mr. Ardolf, he confessed that the accusation was true. Naturally, the parents of the 4-year old contacted the police. This made Mr. Ardolf angry and he decided to seek revenge.

As part of his revenge, court documents indicate that Mr. Ardolf used aircrack, a freely available wireless security tool, to discover the Wired Enhanced Privacy (WEP ) password for his neighbor’s network.  With the neighbor’s WEP password, Mr. Ardolf could use his own computer to connect to the neighbor’s wireless network. Once connected to the wireless network, Mr. Ardolf would be able to access the Internet using the  neighbor’s IP address. Thus, any activity performed by Mr. Ardolf on the Internet would be tracked back to his neighbor’s residence. This provided the opportunity for Mr. Ardolf to take revenge by taking actions that would appear to be done by his neighbor.

Meanwhile, the “hacked” neighbor had been getting reports that coworkers were receiving bizarre email messages that could not be explained. The neighbor had taken the step of bringing in a security consultant to monitor activity on his network. During the time that the monitor was active, the Secret Service investigated an email threat that was found to have been sent from Mr. Ardolf through the neighbor’s wireless network. Since it was sent from “hacked” network, the IP address of the email message came back to the neighbor, not Mr. Ardolf. This lead the Secret Service to visit the neighbor, who turnover over the information from the monitor. In the monitor logs was Mr. Ardolf’s POP3 username and password, presumably known only to Mr. Ardolf. This piece of incriminating information cause the government to turn its attention toward Mr. Ardolf.

The username and password found in the monitor log gave the government probable cause to obtain a search warrant for Mr. Ardolf’s residence. Examination of his computers revealed that he had sent the threatening email, as well as created false email addresses and MySpace accounts designed to appear to be the neighbor.

Further, evidence was uncovered  that Mr. Ardolf had in his possession underage illicit images. He appears to have sent these images from the fake accounts that he created, apparently to “frame” his neighbor.

There are a few lessons that show up from this case. One is that revenge is a powerful and dangerous motivation, one that I covered in my book from a few years ago, High Tech Crimes Revealed.  Revenges is a dangerous motivation since the goal is to damage or hurt another.

Another lesson is that security weaknesses can be used to attack home networks as well as business networks. While WEP encryption is better that no encryption, it suffers from security flaws that can be easily exploited using freely available tools.

In this case, the use of improved WiFi Protect Access (WPA) encryption would have made it more difficult for Mr. Ardolf to break into the neighbor’s wireless network.


Are Macs immune to virus or malware?

A couple of weeks ago, I was asked to check on a Windows-based computer that had recently been infected with a “virus scanner” malware. In this case, the malware (malicious software) would put up a pop up screen that was kind enough to inform you that your computer was loaded with a bunch of virus infections. Further, it offered a link that would allow you to pay for a virus scanner to clean things up, right away. The malware writers made it very difficult for the average user to ignore their malware, as it disabled the buttons that would allow you to close the pop up boxes. Further, it redirected any attempts to run programs such as regedit back to the malware. Cleaning the malware had to be done through Safe-mode.

But, why would I mention this in a posting about Macs and virii? Well, in this case, I was able to track the source of this Windows malware infection back to an email message which contained a series of links to articles that the author thought people would find useful. When the email author, let’s call him Stan, was notified that his email was linked to a malware attack, his response was, quite simply, “That is impossible, because I have a Mac.”

Of course, this is not true. Macs, as good as they are, are not able to scrub malware out of email messages or links on webpages. But, this comment got me thinking, are Macs actually malware free. Dan Moren of Mac World recently released an article entitled “New Mac Trojan horse masquerades as virus scanner“. This articles describes malware written for the Mac that impersonates a virus scanner. Sound familiar?

This is not the first case of the Mac being susceptible to a malware attack. Back in April of 2006, an article from the AP called “Macs no longer immune to viruses, experts say” was released. So, it appears that the Mac has been susceptible to malware for a while.

What Apple has done, it seems,  is taken steps to protect the user environment from malware, as shown in this explanation from Apple. Noteworthy steps include using a sand-box environment and screening the content of downloaded files. So, how did the virus scanner attack affect Macs? Apparently, the malware writers were able find a way around the Mac security and/or screening defenses. It is quite possible that it will happen more often in the future, as Macs continue to become a more popular, more widely used platform and the malware writers become more adept.

So, it appears that Apple has done a lot to secure their user environment, but that malware is still getting through…