add a guide on forensics

Author: 3hhh

README.md

@@ -61,6 +61,7 @@ requests](https://github.com/Qubes-Community/Contents/pulls).
 - [security guidelines](security/security-guidelines.md)
 - [split bitcoin](security/split-bitcoin.md)
 - [split gpg](security/split-gpg.md)
+- [forensics](docs/security/forensics.md)
 
 `system`
 - [understanding and fixing issues with time/clock](system/clock-time.md)

docs/security/forensics.md

@@ -0,0 +1,94 @@
+# Forensics
+
+Sometimes it may be necessary to forensically investigate a Qubes OS VM. This guide describes how this can be accomplished. It is intended for advanced users.
+
+For forensics of Qubes OS `dom0` please refer to any standard Linux forensics guide.
+
+## Disk Forensics
+
+You can [mount disks of all VMs to another investigation VM](https://www.qubes-os.org/doc/mount-lvm-image/) in both r/w and r/o fashion and use your favorite forensic analysis tools.
+
+Users of non-LVM [storage pools](https://dev.qubes-os.org/projects/core-admin-client/en/latest/manpages/qvm-pool.html) may refer to [this code](https://github.com/3hhh/blib/blob/bd993049f8ff6ba9507af06ab388c89f8fb86113/lib/os/qubes4/dom0#L1114).
+
+## Memory Forensics
+
+The following guide uses [volatility3](https://github.com/volatilityfoundation/volatility3) for memory forensics on a previously created memory dump.
+Other tools may work as well.
+
+The VM under analysis is called `vm`. The VM where the memory dump is analyzed is called `analysis-vm`.
+
+### (dom0) Use template VM kernels
+
+Since Qubes OS currently does [not provide kernel debug symbols](https://github.com/QubesOS/qubes-issues/issues/7831) for its default kernels, you will have to switch to VM template kernels at least for the VM under analysis _and_ the analysis VM. Without this step, the analysis tool (here [volatility3](https://github.com/volatilityfoundation/volatility3)) will be unable to interpret the memory dump.
+
+Please follow [the official guide on how to use a kernel installed inside a VM](https://www.qubes-os.org/doc/managing-vm-kernels/#using-kernel-installed-in-the-vm). The required package for `pvh` VMs is called `grub2-xen-pvh`.
+
+### (dom0) Pause the VM under analysis
+
+```
+qvm-pause vm
+```
+
+You can later unpause it via `qvm-unpause vm`. Skipping this step may cause memory smear and render the memory dump useless.
+
+### (dom0) Dump the memory
+
+```
+virsh -c xen:// dump vm vm.dump --live
+sudo chown [user]:[user] vm.dump
+```
+
+### (dom0) Create the analysis-vm
+
+```
+qvm-clone --class StandaloneVM debian-11 analysis-vm
+qvm-prefs analysis-vm label red
+qvm-prefs analysis-vm netvm sys-firewall
+qubes-vm-settings analysis-vm (make sure you have at least 7 GB free system storage and enough private storage to fit your memory dump)
+qvm-copy-to-vm analysis-vm vm.dump
+```
+
+### (analysis-vm) Install [volatility3](https://github.com/volatilityfoundation/volatility3/releases)
+
+Follow the install instructions inside the `REAMDE.md`.
+
+As of 2023 the volatility3 support for Xen memory dumps [is limited](https://github.com/volatilityfoundation/volatility3/issues/896). Your mileage may vary.
+
+### (analysis-vm) Create a volatility binary for convenience
+
+```
+sudo su
+echo '#!/bin/bash'$'\n''python3 "[path to vol.py]/vol.py" "$@"' > /usr/bin/volatility
+chmod +x /usr/bin/volatility
+exit
+```
+
+### (analysis-vm) Build and install [dwarf2json](https://github.com/volatilityfoundation/dwarf2json)
+
+You may have to install golang first (debian: `sudo apt install golang`).
+
+```
+cd ~
+git clone 'https://github.com/volatilityfoundation/dwarf2json'
+cd dwarf2json
+go build
+```
+
+### (analysis-vm) Generate the [symbol tables](https://volatility3.readthedocs.io/en/latest/symbol-tables.html) for volatility3
+
+On debian use `sudo apt install linux-image-amd64-dbg` to install the version matching the kernel version of the VM under analysis.
+
+Afterwards generate the symbol table lookups for volatility3 via `dwarf2json`:
+```
+./dwarf2json linux --elf /usr/lib/debug/boot/vmlinux-[kernel version]-amd64 --system-map /usr/lib/debug/boot/System.map-[kernel version]-amd64 > [volatility path]/volatility3/symbols/[kernel version]-amd64.json
+```
+
+### (analysis-vm) Analyze the memory dump
+
+```
+cd ~
+mv ~/QubesIncoming/dom0/vm.dump ~
+volatility isfinfo (should show the symbol file)
+volatility -f vm.dump banner
+volatility -f vm.dump linux.pslist
+```