Computer forensics analyzes evidence from computers to determine details on computer incidents, similar to how CSI personnel analyze evidence from crime scenes. It uses a variety of different tools to gather and analyze computer evidence. If you’re planning to take the Security+ exam, you should know about some of the basic concepts related to forensic procedures.
For example, can you answer this question?
Q. Security personnel confiscated a user’s workstation after a security incident. Administrators removed the hard drive for forensic analysis, but left it unattended for several hours before capturing an image. What could prevent the company from taking the employee to court over this incident?
A. Witnesses were not identified.
B. A chain of custody was not maintained.
C. An order of volatility was not maintained.
D. A hard drive analysis was not complete.
More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation is available at the end of this post.
Order of Volatility
Order of volatility refers to the order in which you should collect evidence. Volatile doesn’t mean it’s explosive, but rather that it is not permanent. In general, you should collect evidence starting with the most volatile and moving to the least volatile.
For example, random access memory (RAM) is lost after powering down a computer. Because of this, it is important to realize you shouldn’t power a computer down if it’s suspected to be involved in a security incident.
A processor can only work on data in RAM, so all the data in RAM indicates what the system was doing. This includes data users have been working on, system processes, network processes, application remnants, and much more. All of this can be valuable evidence in an investigation, but if a rookie technician turns the computer off, the evidence is lost.
Many forensic tools include the ability to capture volatile data. Once it’s captured, experts can analyze it and gain insight into what the computer and user were doing.
In contrast, data on disks remains on the drive even after powering a system down. This includes any files and even low-level data such as the Master Boot Record on a disk. However, it’s important to protect the data on the disk before analyzing it, and a common method is by capturing an image of the disk.
The order of volatility from most volatile to least volatile is:
- Data in cache memory, including the processor cache and hard drive cache
- Data in RAM, including system and network processes
- Swap file or paging file on the system disk drive
- Data stored on local disk drives
- Logs stored on remote systems
- Archive media
In case you don’t remember from your CompTIA A+ days, the swap file is an extension of RAM and it is stored on the hard drive. However, the swap file isn’t a typical file and it’s rebuilt when the system is rebooted, making it more volatile than other files stored on hard drives.
Remember this
When collecting data for a forensic analysis, you should collect it from the most volatile to the least volatile. The order of volatility is cache memory, regular RAM, swap or paging file, hard drive data, logs stored on remote systems, and archived media.
Witnesses
Another element of an investigation is interviewing witnesses. Witnesses provide firsthand reports of what happened and when it happened. However, witnesses won’t necessarily come forward with relevant information unless someone asks them. Often witnesses don’t recognize what information is valuable.
For example, imagine an attacker who tailgated behind an employee without showing credentials. The employee may notice, but not give it much thought, especially if tailgating is common in the organization. If the attack resulted in loss of equipment or data, an investigator may get a good description of the attacker just by interviewing witnesses.
Track Man-Hours and Expense
Investigations can take an extraordinary amount of time, and for any business, time is money. When budget time rolls around, the departments that can accurately identify how much time and money they spent are more likely to get their requested budget approved.
Additionally, quantitative risk assessments base decisions using specific monetary amounts, such as cost and asset values. If an incident required involvement by security professionals on an incident response team, the man-hours and expenses incurred by the incident response team need to be included in the assessment. Including this data improves the accuracy of the cost values used in the quantitative risk assessment.
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Big Data Analysis
Big Data is a relatively new term and refers to databases that are so large that tools don’t exist to extract meaningful information from them. It’s worth stressing that Big Data is really big. It’s so big that analysts are currently trying to figure out what to name the next iteration. Currently, yottabyte is the largest name and it refers to 1,000 zetabytes. For the record, the order is gigabyte, terabyte, petabyte, exabyte, zettabyte, and then yottabyte. The next name might be hellabyte, using northern California slang of “hella” meaning “a lot.” Seriously. This is one of the names proposed to the International System of Units.
Because tools don’t exist to mine this data, analysts must develop tools for specific needs. As an example, SAS Institute developed tools for Macy’s Inc. to adjust online pricing for 73 million products based on demand and inventory.
Similarly, forensic specialists often must develop tools to analyze Big Data during forensic investigations. Specialists who understand Big Data and can develop tools to analyze it will become more and more valuable as time goes forward. However, they must be able to develop tools that are reliable and provide consistent results. Similarly, the tools must generate the same results each time they are used against the same data, and be able to preserve the evidence. Clearly, analyzing Big Data brings significant new challenges. For example, it’s not a simple matter to create an image of a database as big as a hellabyte.
Q. Security personnel confiscated a user’s workstation after a security incident. Administrators removed the hard drive for forensic analysis, but left it unattended for several hours before capturing an image. What could prevent the company from taking the employee to court over this incident?
A. Witnesses were not identified.
B. A chain of custody was not maintained.
C. An order of volatility was not maintained.
D. A hard drive analysis was not complete.
Answer is B. A chain of custody was not maintained because the hard drive was left unattended for several hours before capturing an image.
Witnesses were not mentioned, but are not needed if the chain of custody was maintained.
The order of volatility does not apply here, but the hard drive is not volatile.
Analysis would occur after capturing an image, but there isn’t any indication it wasn’t done or wasn’t complete.
You might like to review the Implementing Chain of Custody blog post.
