LibZeroEvil & the Research Rootkit project.
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LibZeroEvil & the Research Rootkit project

This is LibZeroEvil & the Research Rootkit project, in which there are step-by-step, experiment-based courses that help to get you started and keep your hands dirty with offensive or defensive development in the Linux kernel, and also guide you with demonstrative examples through the underlying core library, LibZeroEvil, which attempts to be a real-world consumable programming framework for any evil or good kernel-land invaders or defenders.

That being said, it's just the beginning and LibZeroEvil is still in its infancy, serving educational purposes mainly.

Warning

It's never recommended to perform kernel module experiments on a physical machine, unless the owner will never complain about frequent rebooting or forced halting and possible data or work loss.

You have been warned.

Guidelines on Creating New Issues or Contributing

If a course doesn't compile, or do compile but doesn't work as expected, e.g. crashing or hanging your system, feel free to create a new issue. But before that, consider the following.

  1. Search existing issues to ensure that it won't be duplicated.

  2. Attach detailed information of your system, e.g., uname --all, and what your compiler throws on you, i.e., the error information, so that others can successfully reproduce your issue and manage to help you out.

    If you can't figure out which error is the most significant one, paste all of them verbatim inside Markdown triple quotes.

  3. Remember that kernel compatibility issues are the most common ones, since the author paid virtually no attention to that. However, it's my pleasure to learn about and fix them.

  4. Some courses are x64 only for the time being.

Information on Kernel Compatibility

Tested Kernel

My major development environment.

  • Kali

    Linux anon 4.6.0-kali1-amd64 #1 SMP Debian 4.6.3-1kali1 (2016-07-12) x86_64 GNU/Linux.

Compilable Kernel

That is, ./tests/makeall.sh --quiet reports no error, but I haven't tested the functionality.

  • Arch

    Linux anon 4.6.4-1-ARCH #1 SMP PREEMPT Mon Jul 11 19:12:32 CEST 2016 x86_64 GNU/Linux.

  • Ubuntu 14.04

    Linux anon 4.2.0-42-generic #49~14.04.1-Ubuntu SMP Wed Jun 29 20:22:11 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Known Unresolved Compatibility Issues

  • struct dir_context doesn't exist on kernel version 3.10 and earlier.

    For example, CentOS 7, Linux localhost.localdomain 3.10.0-327.22.2.el7.x86_64 #1 SMP Thu Jun 23 17:05:11 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux.

Notice on Directory Structure

The directory structure of this repository might change drastically without any notifications.

Available Courses

More courses might be designed and added here later.

Course 1: Modifying / Hooking the sys_call_table

  • Experiment 1: hello

    Hello World! kernel module.

  • Experiment 2: sys_call_table

    Get sys_call_table 's address by brute-force memory searching starting from PAGE_OFFSET.

  • Experiment 3: write_protection

    Disable or enable Write Protection via the CR0 register.

  • Roundup Experiment 1: fsmon

    A primitive file monitor based on system call hooking.

    Hooked functions: open, unlink, unlinkat.

  • Roundup Experiment 2: psmon

    A primitive process monitor via system call hooking.

    Hooked functions: execve.

    • Notice

      I have seen reports that the method used in this experiment would not work normally due to inconsistent ABI of stub_execve, which requires further investigation.

  • Roundup Experiment 3: fshid

    A primitive file-hiding demonstration using system call hooking.

    Hooked functions: getdents, getdents64.

    Hidden files: 032416_525.mp4.

Course 2: Implementing fundamental functionalities of rootkits

  • Experiment 1: root

    Providing a root backdoor.

  • Experiment 2: komon

    Preventing modules from initializing and functioning by substituting their init and exit functions when MODULE_STATE_COMING is notified to module notifiers.

  • Experiment 3: fshid

    Hiding files by hooking filldir.

  • Experiment 4: pshid

    Hiding processes by hiding entries under /proc.

  • Experiment 5: pthid

    Hiding ports by filtering contents in /proc/net/tcp and the like by hooking the show function of their seq_file interfaces.

  • Experiment 6: kohid

    Hiding modules by hiding entries in /sys/module and filtering contents of /proc/modules by hooking its show function.

    This experiment combines the techniques demonstrated in Experiment 4: pshid and Experiment 5: pthid.

Course 3: Infecting critical kernel modules for persistence and more

  • Experiment 1: elf

    Providing elementary materials on ELF parsing and modifying.

    This experiment implemented an essential tool, i.e. setsym, for following experiments, and also two trivial tools, lssec resembling readelf -S and lssym resembling readelf -s / objdump -t.

    They are coded for 64-bit ELF only, but it shouldn't be difficult to adapt.

  • Experiment 2: noinj

    Hijacking / Hooking the init and exit function of the module with functions in the same module by modifying the symbol table.

  • Experiment 3: codeinj

    Injecting the adapted fshid (See Experiment 3 of Course 2) into a demonstrative simple module (i.e. without static __init or static __exit), and hooking / hijacking its init and exit functions by modifying the symbol table.

  • Roundup Experiment: real

    Injecting the adapted fshid (See Experiment 3 of Course 2) into a real-world kernel module (i.e. with static __init or static __exit) by linking, and hooking / hijacking its init and exit functions by modifying the symbol table.

Course 4: Modifying / Patching the entry_SYSCALL_64

This is x64 only. However, it's not difficult to adapt.

  • Experiment 1: get

    Getting the sys_call_table 's address in the machine code of entry_SYSCALL_64 by searching the identifying bytes ff 14 c5.

  • Experiment 2: set

    Patching the sys_call_table 's address in the machine code of entry_SYSCALL_64 with a faked but innocuous, i.e. unmodified, one.

  • Experiment 3: rec

    Recovering the sys_call_table 's address in the machine code of entry_SYSCALL_64 to that obtained via sys_close -based memory searching.

  • Roundup Experiment: ifmon

    Monitoring network flow (especially GET & POST) by hooking sys_sendto using the method demonstrated in the above three experiments on entry_SYSCALL_64.

Course 5: Inline Hooking

  • Experiment 1: jmp

    Patching the starting bytes of target functions with control flow redirection instructions, e.g. PUSH RET, JMP or INT, which transfer control to our function, where our tasks are performed, including restoring those bytes and invoking the victim function if necessary.

Projects Of Interests

References & Further Readings