Next steps as an Incident Handler

As an Incident Handler, you wish to perform quick triage and find patient-zero as soon as possible. Dissect has some great features to help you with this! The following steps will guide you through quickly obtaining essential information from potentially affected machines and how to analyse the critical information afterwards.

Creating a forensic container

In case of a larger incident, you’ll probably have multiple suspect machines or important crown jewels that you want to investigate as soon as possible. These can be large servers or virtual disks, where taking a full forensic image is a slow process. On top of that, most of the copied information might not be relevant for the incident at hand. acquire has especially been developed to help in this situation. It is capable of rapidly collecting the most essential information from a (live) system into a small sized container (0.5-3.0 GB).

Usually, you’ll find yourself in a situation where you want to make an image of a live system. But for this example, let’s say you wish to have a lightweight forensic container of IE11-Win81-VMWare-disk1.vmdk, instead of the full VMDK file. Using Acquire with the minimal profile results in obtaining the basic relevant artefacts in a small sized container.

Let’s run acquire on the .vmdk file and compare the file sizes afterwards.

$ acquire targets/IE11-Win81-VMWare-disk1.vmdk --profile minimal
$ du targets/{*.vmdk,*.tar} -sh
8.0G    ./IE11-Win81-VMWare-disk1.vmdk
469M    ./MSEDGEWIN10.tar

We end up with a 0.5 GB acquire container, which is 17 times smaller than the original 8 GB .vmdk!

See also

Refer to acquire for a more in-depth explanation of what acquire can do.

If you want to obtain artefacts on a larger scale, you can do so using the examples described in Deployment. It allows you to pack Acquire into a standalone executeable and deploy it in a network!

Creating an MFT timeline

In case of a NTFS file system, creating an MFT timeline is a great way to get a quick initial impression of what happened on a system. To create such a timeline, we can use the special mft_timeline function. It parses the MFT file and returns a human readable output. Since the MFT is an important artefact in the context of digital forensics, the minimal Acquire profile collects this file. To show this, we use the MSEDGEWIN10.tar as a target to produce the MFT timeline with the following command:

$ target-query targets/MSEDGEWIN10.tar -f mft_timeline | sort > MSEDGEWIN10_timeline.txt
$ cat MSEDGEWIN10_timeline.txt
2020-08-10 15:53:20+00:00 SM 105369 c:\Windows\System32\CatRoot\{F7 50E6C3-38EE-11D1-85E5-00C04FC295EE}\ - InUse:True Resident:False Owner:S-1-5-18 Size:10333 VolumeUUID:3fa6fe91-916a-4c89-ab18-cd58de1c8fab
2020-08-10 15:53:22+00:00 SB 105154 c:\Program Files\Common Files\VMware\Drivers\efifw\Win8\efifwver.dll - InUse:True Resident:False Owner:S-1-5-18 Size:2048 VolumeUUID:3fa6fe91-916a-4c89-ab18-cd58de1c8fab
2020-08-10 15:53:22+00:00 SM 105154 c:\Program Files\Common Files\VMware\Drivers\efifw\Win8\efifwver.dll - InUse:True Resident:False Owner:S-1-5-18 Size:2048 VolumeUUID:3fa6fe91-916a-4c89-ab18-cd58de1c8fab
2021-01-22 10:01:00+00:00 F1C 684 c:\Users\Default\Downloads\random_01.dll - InUse:True Resident:False Owner:S-1-5-32-544 Size:3443712 VolumeUUID:3fa6fe91-916a-4c89-ab18-cd58de1c8fab

After sort is complete you can open the MFT timeline in your favorite text editor / pager like vim or less and use common text manipulation tools such as grep, rg, or awk to start your triage!

This example is not limited to the mft_timeline function. For example, for the Windows event logs we can achieve the same thing with a similar command:

$ target-query targets/MSEDGEWIN10.tar -f evtx -s | sort > MSEDGEWIN10_evtx.txt

Note that we have to add the -s (or --string) argument now to get human readable output, because the evt and evtx functions return records, whereas the mft_timeline directly returned lines of text.

Look for signs of persistence

Once attackers gain access to a system, it is quite likely that they want to use some sort of persistence. Since it’s crucial for a digital forensic investigation to find possible used persistence techniques, we would like to check the locations signs of persistence can be found for each target. Some of the functions we can use include:

  • runkeys

  • services

  • tasks

  • clsid

  • startupinfo

Let’s use them by running the following command:

$ target-query targets/ -f runkeys,services,tasks,clsid,startupinfo

For analysis of the results, you can use your favourite search platform or perform a similar search as explained in the investigation steps for a security analyst like Finding hijacked CLSIDs.

Write target-query functions output to a file

target-query will quickly become your best friend during an investigation. From the Introduction page, you’ve seen how you can easily query information and artefacts from your targets by using the functions that are available to you. There are a couple of functions that return information and artefacts that you would almost always want to take a look at during an investigation, including but not limited to:

  • evtx

  • evt

  • mft

  • usnjrnl

  • prefetch

  • services

  • tasks

  • cronjobs

  • bashhistory

  • btmp, wtmp

Since time is an Incident Handler’s worst enemy, you probably don’t want to run each of these function separately for each target. Therefore, let’s create a small bash script that loops over these functions and writes the output to separate output files:

functions=("evt" "evtx") # add additional plugins to be executed plugins as you see fit!
find targets/ -type l -print0 |
    while IFS= read -r -d '' t; do
        target=$(basename "$t")
        echo "[+] Running functions for target: $t"
        mkdir -p "host/$target"
        for f in ${functions[@]}; do
                echo "[-] Running function $f"
                target-query $t -f $f -q 2>> "host/$target/$f.log" > "host/$target/$f.rec"

Now, for each host in the host/ folder, we have separate record files for each function. Note that some functions are OS based, which make them incompatible with another OS. However, target-query will just skip a target when the function is not compatible (which can be seen in the log files). So there is no need to change the essential function list for each target.

To further speed up this process, you could use xargs to run multiple instances of target-query at the same time.

Load records into a search platform

One of the things you probably wish to do with the obtained records, is importing them to your search platform of choice. We will discuss how to do this for two of the common ones here, namely Splunk and Elastic Search. Using rdump makes this really easy, since it contains adapters for both of these. These adapters can be invoked when using rdump in combination with the -w parameter.


rdump can produce Elastic and Splunk compatible output out of the box. Setting up these environments is left as an exercise to the reader.

Now, let’s assume that we are running the search platforms on our local machine (port 1337 and 1338 for Splunk and Elastic, respectively). The following small bash script will import all record files in the host/ directory to the platforms:

find host/ -type f -print0 |
    while IFS= read -r -d '' r; do
        echo "[+] Importing $r into search platforms"
        rdump "$r" -w splunk://localhost:1337 2>> "${r%.log}"
        rdump "$r" -w elastic://localhost:1338 2>> "${r%.log}"