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License Project Status: Active – The project has reached a stable, usable state and is being actively developed.

About Elkeid(AgentSmith-HIDS) Driver

English | 简体中文

Elkeid Driver is a one-of-a-kind Kernel Space HIDS agent designed for Cyber-Security.

Elkeid Driver hooks kernel functions via Kprobe, providing rich and accurate data collection capabilities, including kernel-level process execve probing, privilege escalation monitoring, network audition, and much more. The Driver treats Container-based monitoring as a first-class citizen as Host-based data collection by supporting Linux Namespace. Compare to User Space agents on the market, Elkeid provides more comprehensive information with massive performance improvement.

Elkeid has already been deployed massively for HIDS usage in world-class production environments. With its marvelous data collection ability, Elkeid also supports Sandbox, Honeypot, and Audition data requirements.

Notice

DO NOT insmod the ko in the production machines if you have not well tested it.

Quick Test

First you need install Linux Headers

# clone and build
git clone https://github.com/bytedance/Elkeid.git
cd Elkeid/driver/LKM/
make clean && make
< CentOS only: run build script instead >
sh ./centos_build_ko.sh

# load and test (should run as root)
insmod hids_driver.ko
dmesg | tail -n 20
test/rst -q
< "CTRL + C" to quit >

# unload
rmmod hids_driver

Pre-build Ko

How To Get

If all urls failed, please build elkeid kernel module yourself.

wget "http://lf26-elkeid.bytetos.com/obj/elkeid-download/ko/hids_driver_1.7.0.10_$(uname -r)_amd64.ko"

How to Test

You can test the kernel module with LTP (better with KASAN turned on). Here's the LTP-test-case configuration file for your reference: LTP-test-case.

About the compatibility with Linux distributions

Distro Version x64 kernel Suffix
Debian 8,9,10 3.16~5.4.X -
Ubuntu 14.04,16.04,18.04,20.04 3.12~5.4.X generic
CentOS 6.X,7.X,8.X 2.6.32.0~5.4.X el6,el7,el8
Amazon 2 4.9.X~4.14.X amzn2
AlibabaCloudLinux 3 4.19.X~5.10.X al7,al8
EulerOS V2.0 3.10.X -

About ARM64 (AArch64) Support

  • Yes

About the compatibility with Kernel versions

  • Linux Kernel Version >= 2.6.32 && <= 6.3

About the compatibility with Containers

Source Nodename
Host hostname
Docker container name
K8s pod name

Hook List

Hook DataType Note Default
write 1 OFF
open 2 OFF
mprotect 10 only PROT_EXEC OFF
nanosleep 35 OFF
connect 42 ON
accept 43 OFF
bind 49 ON
execve 59 ON
process exit 60 OFF
kill 62 OFF
rename 82 ON
link 86 ON
ptrace 101 only PTRACE_POKETEXT or PTRACE_POKEDATA ON
setsid 112 ON
prctl 157 only PR_SET_NAME ON
mount 165 ON
tkill 200 OFF
exit_group 231 OFF
memfd_create 356 ON
dns query 601 ON
create_file 602 ON
load_module 603 ON
update_cred 604 only old uid ≠0 && new uid == 0 ON
unlink 605 OFF
rmdir 606 OFF
call_usermodehelper_exec 607 ON
file_write 608 OFF
file_read 609 OFF
usb_device_event 610 ON
privilege_escalation 611 ON
port-scan detection 612 tunable via module param: psad_switch OFF

Anti Rootkit List

Rootkit DataType Default
interrupt table hook 703 ON
syscall table hook 701 ON
proc file hook 700 ON
hidden kernel module 702 ON

Driver TransData Pattern

Data Protocol

Every hit of the hook-points above will generate a record, and the records are separated by deliminator '\x17'.

Each record contains several data items, which are separated by deliminator '\x1e'.

A record generally contains Common Data and Private Data, with the exception of Anti-rootkit, which does NOT have Common Data.

Common Data

-------------------------------------------------------------------------------
|1        |2  |3  |4  |5   |6   |7   |8  |9   |10      |11       |12 |13      |
-------------------------------------------------------------------------------
|data_type|uid|exe|pid|ppid|pgid|tgid|sid|comm|nodename|sessionid|pns|root_pns|
-------------------------------------------------------------------------------

Write Data (1)

-----------
|14   |15 | 
-----------
|file||buf|
-----------

Open Data (2)

---------------------
|14   |15  |16      | 
---------------------
|flags|mode|filename|
---------------------

Mprotect Data (10)

-----------------------------------------------------
|14           |15       |16        |17     |18      |
-----------------------------------------------------
|mprotect_prot|owner_pid|owner_file|vm_file|pid_tree|
-----------------------------------------------------

Nanosleep Data (35)

----------
|14 |15  |
----------
|sec|nsec|
----------

Connect Data (42)

-----------------------------------
|14       |15 |16   |17 |18   |19 |
-----------------------------------
|sa_family|dip|dport|sip|sport|res|
-----------------------------------

Accept Data (43)

-----------------------------------
|14       |15 |16   |17 |18   |19 |
-----------------------------------
|sa_family|dip|dport|sip|sport|res|
-----------------------------------

Bind Data (49)

-------------------------
|14       |15 |16   |17 |
-------------------------
|sa_family|sip|sport|res|
-------------------------

Execve Data (59)

-----------------------------------------------------------------------------------------------------
|14  |15      |16   |17    |18 |19   |20 |21   |22       |23      |24 |25        |26 |27        |28 |
-----------------------------------------------------------------------------------------------------
|argv|run_path|stdin|stdout|dip|dport|sip|sport|sa_family|pid_tree|tty|socket_pid|ssh|ld_preload|res|
-----------------------------------------------------------------------------------------------------

Note:

  • socket_exe/dip/dport/sip/sport/sa_family is collected from the process's fds

  • ssh/ld_preload is collected from the process's env

Process Exit Data (60)

Only contains fields in Common Data

Kill Data (62)

----------------
|14        |15 |
----------------
|target_pid|sig|
----------------

Rename Data (82)

-------------------------
|14      |15      |16   |
-------------------------
|old_name|new_name|sb_id|
-------------------------

Link Data (86)

-------------------------
|14      |15      |16   |
-------------------------
|old_name|new_name|sb_id|
-------------------------

Ptrace Data (101)

----------------------------------------------
|14            |15        |16  |17  |18      |
----------------------------------------------
|ptrace_request|target_pid|addr|data|pid_tree|
----------------------------------------------

Setsid Data (112)

Only contains fields in Common Data

Prctl Data (157)

_________________
|14    |15      | 
-----------------
|option|new_name|
-----------------

Mount Data (165)

_____________________________________
|14      |15 |16       |17    |18   | 
-------------------------------------
|pid_tree|dev|file_path|fstype|flags|
-------------------------------------

Tkill data (200)

----------------
|14        |15 |
----------------
|target_pid|sig|
----------------

Exit Group Data (231)

Only contains fields in Common Data

Memfd Create Data (356)

______________
|14    |15   | 
--------------
|fdname|flags|
--------------

Dns Query Data (601)

--------------------------------------------------
|14   |15       |16 |17   |18 |19   |20    |21   |
--------------------------------------------------
|query|sa_family|dip|dport|sip|sport|opcode|rcode|
--------------------------------------------------

Create File data (602)

----------------------------------------------------------
|14 	  |15 |16   |17 |18   |19       |20        |21   |
----------------------------------------------------------
|file_path|dip|dport|sip|sport|sa_family|socket_pid|sb_id|
----------------------------------------------------------

Load Module Data (603)

---------------------------
|14      |15      |16     |
---------------------------
|ko_file|pid_tree|run_path|
---------------------------

Update Cred Data (604)

----------------------
|14      |15     |16 | 
----------------------
|pid_tree|old_uid|res|
----------------------

Unlink Data (605)

------
|14  |
------
|file|
------

Rmdir Data (606)

------
|14  |
------
|file|
------

call_usermodehelper_exec Data (607)

-------------------------
|1        |2  |3   |4   |
-------------------------
|data_type|exe|argv|wait|
-------------------------

File Write Data (608)

------------
|14  |15   |
------------
|file|sb_id|
------------
Need to join the to-watch list through Diver Filter, see "About Driver Filter" section for details

File Read Data (609)

------------
|14  |15   |
------------
|file|sb_id|
------------
Need to join the to-watch list through Diver Filter, see "About Driver Filter" section for details

USB Device Event Data (610)

-----------------------------------------
|14          |15          |16    |17    |
-----------------------------------------
|product_info|manufacturer|serial|action|
-----------------------------------------
action = 1 is USB_DEVICE_ADD
action = 2 is USB_DEVICE_REMOVE

Privilege Escalation (611)

------------------------------
|14   |15      |16    |17    |
------------------------------
|p_pid|pid_tree|p_cred|c_cred|
------------------------------
p_cred = uid|euid|suid|fsuid|gid|egid|sgid|fsgid
c_cred = uid|euid|suid|fsuid|gid|egid|sgid|fsgid

Port-scan attack detection (612)

------------------------------------------
|1   |2        |3  |4    |5  |6    |7    |
------------------------------------------
|type|sa_family|sip|sport|dip|dport|flags|
------------------------------------------

Proc File Hook (700)

-----------------------
|1        |2          |
-----------------------
|data_type|module_name|
-----------------------

Syscall Table Hook Data (701)

--------------------------------------
|1        |2          |3             |
--------------------------------------
|data_type|module_name|syscall_number|
--------------------------------------

Hidden Kernel Module Data (702)

-----------------------
|1        |2          |
-----------------------
|data_type|module_name|
-----------------------

Interrupt Table Hook Data (703)

----------------------------------------
|1        |2          |3               |
----------------------------------------
|data_type|module_name|interrupt_number|
----------------------------------------

About Driver Filter

Elkeid driver supports allowlist to filter out unwanted data. We provide two types of allowlists, 'exe' allowlist and 'argv' allowlist. 'exe' allowlist acts on execve/create file/dns query/connect hooks, while 'argv' allowlist only acts on execve hook. For performance and stability concerns, both 'exe' and 'argv' allowlist only supports 64-elements-wide capacity.

allowlist driver is in: /dev/hids_driver_allowlist

Operations Flag Example
ADD_EXECVE_EXE_SHITELIST Y(89) echo Y/bin/ls > /dev/someone_allowlist
DEL_EXECVE_EXE_SHITELIST F(70) echo F/bin/ls > /dev/someone_allowlist
DEL_ALL_EXECVE_EXE_SHITELIST w(119) echo w/del_all > /dev/someone_allowlist
EXECVE_EXE_CHECK y(121) echo y/bin/ls > /dev/someone_allowlist && dmesg
ADD_EXECVE_ARGV_SHITELIST m(109) echo m/bin/ls -l > /dev/someone_allowlist
DEL_EXECVE_ARGV_SHITELIST J(74) echo J/bin/ls -l > /dev/someone_allowlist
DEL_ALL_EXECVE_ARGV_SHITELIST u(117) echo u/del_all > /dev/someone_allowlist
EXECVE_ARGV_CHECK z(122) echo z/bin/ls -l > /dev/someone_allowlist && dmesg
PRINT_ALL_ALLOWLIST .(46) echo ./print_all > /dev/someone_allowlist && dmesg
ADD_WRITE_NOTIFI W(87) echo W/etc/passwd > /dev/someone_allowlist or echo W/etc/ssh/ > /dev/someone_allowlist support dir
DEL_WRITE_NOTIFI v(120) echo v/etc/passwd > /dev/someone_allowlist
ADD_READ_NOTIFI R(82) echo R/etc/passwd > /dev/someone_allowlist or echo R/etc/ssh/ > /dev/someone_allowlist support dir
DEL_READ_NOTIFI s(115) echo s/etc/passwd > /dev/someone_allowlist
DEL_ALL_NOTIFI A(65) echo A/del_all_file_notift > /dev/someone_allowlist

Filter define is:

#define ADD_EXECVE_EXE_SHITELIST 89         /* Y */
#define DEL_EXECVE_EXE_SHITELIST 70         /* F */
#define DEL_ALL_EXECVE_EXE_SHITELIST 119    /* w */
#define EXECVE_EXE_CHECK 121                /* y */
#define PRINT_ALL_ALLOWLIST 46              /* . */
#define ADD_EXECVE_ARGV_SHITELIST 109       /* m */
#define DEL_EXECVE_ARGV_SHITELIST 74        /* J */
#define DEL_ALL_EXECVE_ARGV_SHITELIST 117   /* u */
#define EXECVE_ARGV_CHECK 122               /* z */

#define ADD_WRITE_NOTIFI 87                 /* W */
#define DEL_WRITE_NOTIFI 120                /* v */
#define ADD_READ_NOTIFI 82                  /* R */
#define DEL_READ_NOTIFI 115                 /* s */
#define DEL_ALL_NOTIFI 65                   /* A */

Performance Stats of Elkeid Driver

Testing Environment(VM):

CPU Intel(R) Xeon(R) Platinum 8260 CPU @ 2.40GHz 8 Core
RAM 16GB
OS/Kernel Debian9 / Kernel Version 4.14

Testing Load:

syscall ltp
connect ./runltp -f syscalls -s connect -t 5m
bind ./runltp -f syscalls -s bind -t 5m
execve ./runltp -f syscalls -s execve -t 5m
security_inode_create ./runltp -f syscalls -s open -t 5m
ptrace ./runltp -f syscalls -s ptrace -t 5m

Key kprobe Handler Testing Result(90s)

hook function name Average Delay(us) TP99(us) TP95(us) TP90(us)
connect_syscall_handler 0.7454 3.5017 1.904 1.43
connect_syscall_entry_handler 0.0675 0.3 0.163 0.1149
udp_recvmsg_handler 9.1290 68.7043 18.5357 15.9528
udp_recvmsg_entry_handler 0.5882 7.5631 0.7811 0.3665
bind_handler 2.2558 10.0525 8.1996 7.041
bind_entry_handler 0.4704 1.0180 0.8234 0.6739
execve_entry_handler 6.9262 12.2824 9.437 8.638
execve_handler 15.2102 36.0903 25.9272 23.068
security_inode_create_pre_handler 1.5523 7.9454 5.5806 3.1441
ptrace_pre_handler 0.2039 0.4648 0.254 0.228

udp_recvmsg_handler will work only if the port is equal 53 or 5353

Original Testing Data: Benchmark Data

About Deploy

You can use DKMS or Pre-packaged ko file

  • install driver: insmod hids_driver.ko
  • remove driver: first you need kill userspace agent and rmmod hids_driver.ko

Known Bugs

License

Elkeid kernel module are distributed under the GNU GPLv2 license.