Volshell - A CLI tool for working with memory
Volshell is a utility to access the volatility framework interactively with a specific memory image. It allows for direct introspection and access to all features of the volatility library from within a command line environment.
Starting volshell
Volshell is started in much the same way as volatility. Rather than providing a plugin, you just specify the file. If the operating system of the memory image is known, a flag can be provided allowing additional methods for the specific operating system.
$ volshell.py -f <path-to-memory-image> [-w|-m|-l]
The flags to specify a known operating system are -w for windows, -m for mac and -l for linux. Volshell will run through the usual automagic, trying to load the memory image. If no operating system is specified, all automagic will be run.
When volshell starts, it will show the version of volshell, a brief message indicating how to get more help, the current operating system mode for volshell, and the current layer available for use.
Volshell (Volatility 3 Framework) 2.0.2
Readline imported successfully PDB scanning finished
Call help() to see available functions
Volshell mode : Generic
Current Layer : primary
Current Symbol Table : None
Current Kernel Name : None
(primary) >>>
Volshell itself is essentially a plugin, but an interactive one. As such, most values are accessed through self although there is also a context object whenever a context must be provided.
The prompt for the tool will indicate the name of the current layer (which can be accessed as self.current_layer from within the tool).
The generic mode is quite limited, won’t have any symbols loaded and therefore won’t be able to display much information. When an operating system is chosen, the appropriate symbols should be loaded and additional functions become available. The mode cannot easily be changed once the tool has started.
Accessing objects
All operating systems come with their equivalent of a process list, aliased to the function ps(). Running this will provide a list of volatility objects, based on the operating system in question. We will use these objects to run our examples against.
We’ll start by creating a process variable, and putting the first result from ps() in it. Since the shell is a python environment, we can do the following:
(layer_name) >>> proc = ps()[0]
(layer_name) >>> proc
<EPROCESS symbol_table_name1!_EPROCESS: layer_name @ 0xe08ff2459040 #1968>
When printing a volatility structure, various information is output, in this case the type_name, the layer and offset that it’s been constructed on, and the size of the structure.
We can directly access the volatility information about a structure, using the .vol attribute, which contains basic information such as structure size, type_name, and the list of members amongst others. However, volshell has a built-in mechanism for providing more information about a structure, called display_type or dt. This can be given either a type name (which if not prefixed with symbol table name, will use the kernel symbol table identified by the automagic).
(layer_name) >>> dt('_EPROCESS')
symbol_table_name1!_EPROCESS (1968 bytes)
0x0 : Pcb symbol_table_name1!_KPROCESS
0x2d8 : ProcessLock symbol_table_name1!_EX_PUSH_LOCK
0x2e0 : RundownProtect symbol_table_name1!_EX_RUNDOWN_REF
0x2e8 : UniqueProcessId symbol_table_name1!pointer
...
It can also be provided with an object and will interpret the data for each in the process:
(layer_name) >>> dt(proc)
symbol_table_name1!_EPROCESS (1968 bytes)
0x0 : Pcb symbol_table_name1!_KPROCESS 0xe08ff2459040
0x2d8 : ProcessLock symbol_table_name1!_EX_PUSH_LOCK 0xe08ff2459318
0x2e0 : RundownProtect symbol_table_name1!_EX_RUNDOWN_REF 0xe08ff2459320
0x2e8 : UniqueProcessId symbol_table_name1!pointer 4
...
These values can be accessed directly as attributes
(layer_name) >>> proc.UniqueProcessId
356
Pointer structures contain the value they point to, but attributes accessed are forwarded to the object they point to. This means that pointers do not need to be explicitly dereferenced to access underling objects.
(layer_name) >>> proc.Pcb.DirectoryTableBase
4355817472
Running plugins
It’s possible to run any plugin by importing it appropriately and passing it to the display_plugin_output or dpo method. In the following example we’ll provide no additional parameters. Volatility will show us which parameters were required:
(layer_name) >>> from volatility3.plugins.windows import pslist
(layer_name) >>> display_plugin_output(pslist.PsList)
Unable to validate the plugin requirements: ['plugins.Volshell.VH3FSA1JBG0QP9E62Z8OT5UCIMLNYKW4.PsList.kernel']
We can see that it’s made a temporary configuration path for the plugin, and that the kernel requirement was not fulfilled.
We can see all the options that the plugin can accept by access the get_requirements() method of the plugin. This is a classmethod, so can be called on an uninstantiated copy of the plugin.
(layer_name) >>> pslist.PsList.get_requirements()
[<ModuleRequirement: kernel>, <BooleanRequirement: physical>, <ListRequirement: pid>, <BooleanRequirement: dump>]
We can provide arguments via the dpo method call:
(layer_name) >>> display_plugin_output(pslist.PsList, kernel = self.config['kernel'])
PID PPID ImageFileName Offset(V) Threads Handles SessionId Wow64 CreateTime ExitTime File output
4 0 System 0x8c0bcac87040 143 - N/A False 2021-03-13 17:25:33.000000 N/A Disabled
92 4 Registry 0x8c0bcac5d080 4 - N/A False 2021-03-13 17:25:28.000000 N/A Disabled
356 4 smss.exe 0x8c0bccf8d040 3 - N/A False 2021-03-13 17:25:33.000000 N/A Disabled
...
Here we’ve provided the kernel name that was requested by the volshell plugin itself (the generic volshell does not load a kernel module, and instead only has a TranslationLayerRequirement). A different module could be created and provided instead. The context used by the dpo method is always context.
Instead of printing the results directly to screen, they can be gathered into a TreeGrid objects for direct access by using the generate_treegrid or gt command.
(layer_name) >>> treegrid = gt(pslist.PsList, kernel = self.config['kernel'])
(layer_name) >>> treegrid.populate()
Treegrids must be populated before the data in them can be accessed. This is where the plugin actually runs and produces data.
Running scripts
It might be beneficial to code up a small snippet of code, and execute that on a memory image, rather than writing a full plugin.
The snippet should be lines that will be executed within the volshell context (as such they can immediately access self and context, for example). These can be executed using the run_script or rs command, or by providing the file on the command line with –script.
For example, to load a layer and extract bytes from a particular offset into a new file, the following snippet could be used:
import volatility3.framework.layers.mynewlayer as mynewlayer
layer = cc(mynewlayer.MyNewLayer, on_top_of = 'primary', other_parameter = 'important')
with open('output.dmp', 'wb') as fp:
for i in range(0, 0x4000000, 0x1000):
data = layer.read(i, 0x1000, pad = True)
fp.write(data)
As this demonstrates, all of the python is accessible, as are the volshell built in functions (such as cc which creates a constructable, like a layer or a symbol table).
User Convenience
There are functions available that make often-done tasks easier, and generally provide a shell-like experience. These can be listed using help() which, as already mentioned, is advertised when volshell starts.
Loading files
Files can be loaded as physical layers using the load_file or lf command, which takes a filename or a URI. This will be added to context.layers and can be accessed by the name returned by lf.
Regex
It is easy to scan for some bytes or a pattern using regex_scan or rx.
(layer_name) >>> rx(rb"(Linux version|Darwin Kernel Version) [0-9]+\.[0-9]+\.[0-9]+")
0x880001400070 4c 69 6e 75 78 20 76 65 72 73 69 6f 6e 20 33 2e Linux.version.3.
0x880001400080 32 2e 30 2d 34 2d 61 6d 64 36 34 20 28 64 65 62 2.0-4-amd64.(deb
0x880001400090 69 61 6e 2d 6b 65 72 6e 65 6c 40 6c 69 73 74 73 ian-kernel@lists
0x8800014000a0 2e 64 65 62 69 61 6e 2e 6f 72 67 29 20 28 67 63 .debian.org).(gc
0x8800014000b0 63 20 76 65 72 73 69 6f 6e 20 34 2e 36 2e 33 20 c.version.4.6.3.
0x8800014000c0 28 44 65 62 69 61 6e 20 34 2e 36 2e 33 2d 31 34 (Debian.4.6.3-14
0x8800014000d0 29 20 29 20 23 31 20 53 4d 50 20 44 65 62 69 61 ).).#1.SMP.Debia
0x8800014000e0 6e 20 33 2e 32 2e 35 37 2d 33 2b 64 65 62 37 75 n.3.2.57-3+deb7u
0x880001769027 4c 69 6e 75 78 20 76 65 72 73 69 6f 6e 20 33 2e Linux.version.3.
0x880001769037 32 2e 30 2d 34 2d 61 6d 64 36 34 20 28 64 65 62 2.0-4-amd64.(deb
0x880001769047 69 61 6e 2d 6b 65 72 6e 65 6c 40 6c 69 73 74 73 ian-kernel@lists
0x880001769057 2e 64 65 62 69 61 6e 2e 6f 72 67 29 20 28 67 63 .debian.org).(gc
0x880001769067 63 20 76 65 72 73 69 6f 6e 20 34 2e 36 2e 33 20 c.version.4.6.3.
0x880001769077 28 44 65 62 69 61 6e 20 34 2e 36 2e 33 2d 31 34 (Debian.4.6.3-14
0x880001769087 29 20 29 20 23 31 20 53 4d 50 20 44 65 62 69 61 ).).#1.SMP.Debia
0x880001769097 6e 20 33 2e 32 2e 35 37 2d 33 2b 64 65 62 37 75 n.3.2.57-3+deb7u
0xffff81400070 4c 69 6e 75 78 20 76 65 72 73 69 6f 6e 20 33 2e Linux.version.3.
0xffff81400080 32 2e 30 2d 34 2d 61 6d 64 36 34 20 28 64 65 62 2.0-4-amd64.(deb
0xffff81400090 69 61 6e 2d 6b 65 72 6e 65 6c 40 6c 69 73 74 73 ian-kernel@lists
0xffff814000a0 2e 64 65 62 69 61 6e 2e 6f 72 67 29 20 28 67 63 .debian.org).(gc
0xffff814000b0 63 20 76 65 72 73 69 6f 6e 20 34 2e 36 2e 33 20 c.version.4.6.3.
0xffff814000c0 28 44 65 62 69 61 6e 20 34 2e 36 2e 33 2d 31 34 (Debian.4.6.3-14
0xffff814000d0 29 20 29 20 23 31 20 53 4d 50 20 44 65 62 69 61 ).).#1.SMP.Debia
0xffff814000e0 6e 20 33 2e 32 2e 35 37 2d 33 2b 64 65 62 37 75 n.3.2.57-3+deb7u
0xffff81769027 4c 69 6e 75 78 20 76 65 72 73 69 6f 6e 20 33 2e Linux.version.3.
0xffff81769037 32 2e 30 2d 34 2d 61 6d 64 36 34 20 28 64 65 62 2.0-4-amd64.(deb
0xffff81769047 69 61 6e 2d 6b 65 72 6e 65 6c 40 6c 69 73 74 73 ian-kernel@lists
0xffff81769057 2e 64 65 62 69 61 6e 2e 6f 72 67 29 20 28 67 63 .debian.org).(gc
0xffff81769067 63 20 76 65 72 73 69 6f 6e 20 34 2e 36 2e 33 20 c.version.4.6.3.
0xffff81769077 28 44 65 62 69 61 6e 20 34 2e 36 2e 33 2d 31 34 (Debian.4.6.3-14
0xffff81769087 29 20 29 20 23 31 20 53 4d 50 20 44 65 62 69 61 ).).#1.SMP.Debia
0xffff81769097 6e 20 33 2e 32 2e 35 37 2d 33 2b 64 65 62 37 75 n.3.2.57-3+deb7u
An optional size can be given for the displayed results as with the other fuctions (db, dw, dd, dq, etc).
You can, of course, specify a different layer name as well.