Information Security

Assignment 8: Forensics

Like assignments 4-7, this is a group assignment . There is no need to use the same groups you had in past assignments - you may chose new partners.

In this project you will investigate the murder of Hapless Victim, a well-known campus personality, who was killed while working in the CS building sometime between midnight and 6 a.m. Officers recovered a projectile known as a "nerf blaster dart" which appears, inexplicably, to have been the cause of death.

Officers have arrested the leading suspect, Nefarious Criminal, and seized his computer. An image of his hard drive is available for investigation (3.2 gigabye download; SHA1 Hash: 84ed06ce5fb8461b72511ce2ed391f8d1e5656f2 ('sha1sum -b filename' on Linux)). Your job is to conduct a forensic examination of this hard drive image and document any evidence relating to the murder.

Tasks and deliverables

The deliverables for this project are your answers to the numbered questions below. Your answers should be complete but concise. None of the questions should require more than one or two paragraphs to answer.

For each prompt, explain the investigatory methods you used and the evidence that supports your conclusion. Submit your answers in HTML or PDF format, in a file called index.html or homework8.pdf. You may include recovered files in your submission, but your report should clearly indicate which of these files are relevant to each response.

As you investigate, be on the lookout for evidence of any other machines or network services that the suspect may have used. These may contain important evidence and raise further questions you'll need to investigate. Per Section 4.1, be sure to contact your supervisor (i.e., the teaching assistants) before attempting to access any such machines or accounts. Again, start early; management has been known to take up to 24 hours to respond on weekdays and longer on weekends, although we try to respond promptly.

Try booting the suspect's machine and using it normally. What specific behaviors of this machine make this a bad idea? We strongly recommend that you mount the suspect's drive from a safe system before continuing (see the hints on creating a raw image later in this section).
What operating system does the suspect use? Be careful and specific; e.g., say "Windows 2000" instead of just "Windows." (No attachment necessary.)
What is the username of the account typically used by the suspect? (No attachment necessary.)
Do you have any evidence that the suspect had an accomplice who was physically present on the night of the crime?
Were there any suspicious-looking encrypted files on the machine? If so, please attach their contents and a brief description of how you obtained the contents.
What evidence do you have that the suspect owned or was researching weapons of the kind involved in the murder? Please attach the specific evidence and a brief explanation.
Did the suspect try to delete any files before his arrest? Please attach the name(s) of the file(s) and any indications of their contents that you can find. (Hint: We will be impressed enough to give extra credit if you manage to recover the original contents of a particular incriminating file, but we do not expect you to do so.)
Is there anything else suspicious about the machine?

Submitting

You should write up your answers to the above questions as you have for previous assignments. Include these answers as well as any files from the image which you wish to use as exhibits to support those answers and submit them as a zip file here.

Hints and resources

In addition to the hints we've dropped elsewhere, here is an incomplete list of some things you may want to try:

Examine the system logs.
Check for deleted or encrypted files.
Search the drive image itself (e.g., using grep -a or strings) for strings that may indicate relevance to your investigation. You'll need to convert the disk image to a "raw" binary image; see the help for the VBoxManage clonehd command.

Some additional resources that may help you:

http://darkdust.net/writings/diskimagesminihowto explains how to find the partitions in a disk image and mount one of them, albeit in a different context than forensics. http://en.wikipedia.org/wiki/Disk_partitioning provides some background that you may be missing.
John the Ripper (http://www.openwall.com/john/) is the canonical Unix password cracker. Cain and Abel (http://oxid.it/cain.html) and Hydra (http://www.thc.org/thc-hydra/) are two other well-known general-purpose password crackers, frackzip (http://home.schmorp.dc/marc/fcrackzip.html) is a ZIP password cracker, and pdfcrack (http://sourceforge.net/projects/pdfcrack/) is a PDF password cracker. John, fcrackzip, and pdfcrack are conveniently available in the Debian package repositories and may be available for other Linux distros as well. When using a password cracker, it is wise to make sure that the password is not susceptible to a dictionary attack and does not use a restricted character set (e.g., lowercase letters, letters only, letters and numbers only) before spending time on a full brute-force crack. It is also a good idea to crack a very vulnerable password first to make sure you are using the tool correctly.
"Deleted files recovery howto" (http://e2undel.sourceforge.net/recovery-howto.html) explains how to recover deleted files on the ext2 filesystem using e2undel and debugfs. http://www.xs4all.nl/~carlo17/howto/undelete_ext3.html explains how to attempt to recover deletes files on the ext3 filesystem.
A general working knowledge of Linux is probably helpful for this project as well. If you don't have this yet, you may need to spend a little time Googling and/or experimenting to get up to speed. The TAs will also answer general Linux questions as a last resort.

Policies and mechanics

Ethics

In this project you will be investigating the use of computers as part of an entirely fictitious crime scenario. You may access Web pages and other obviously-public computer services in a read-only fashion, but you must not attempt to log into any computers or accounts over which you do not already have sole control, even if you recover authentication credentials for those accounts from your analysis. If you think that doing so is necessary (hint, hint), you must first email the teaching assistants.

Collaboration

As usual, you may not collaborate outside your group. The number of pieces of evidence you find, the techniques you try, how successful those techniques are, the general process you follow, etc., are considered part of your solution and must not be shared between groups.

If you get stuck

Given the nature of the assignment and its strict collaboration policy, we recognize the need for some hints. We have developed standard hints for each question we have asked in the assignment; if your group gets stuck, you may email the teaching assistants with the names of your group members, the question for which you would like a hint, and the progress you have made thus far on that question. Each group may receive up to three hints in total, and we will enforce a one-hour delay between hints for each group.

Requesting access to a remote machine does not count as a hint request, nor does asking for help with the first three questions, which are intended to help you get started.

We will respond to hint requests in a best-effort, first-come first-served fashion. In particular, you will not necessarily receive a hint before the homework deadline if you request one within 24 hours of the deadline. Start early!