Unhide is a forensic tool to find processes and TCP/UDP ports hidden by rootkits, Linux kernel modules or by other techniques. It includes two utilities: unhide and unhide-tcp. unhide detects hidden processes using the following six techniques: * Compare /proc vs /bin/ps output * Compare info gathered from /bin/ps with info gathered by walking thru the procfs. * Compare info gathered from /bin/ps with info gathered from syscalls (syscall scanning). * Full PIDs space occupation (PIDs bruteforcing) * Reverse search, verify that all thread seen by ps are also seen by the kernel (/bin/ps output vs /proc, procfs walking and syscall) * Quick compare /proc, procfs walking and syscall vs /bin/ps output unhide-tcp identifies TCP/UDP ports that are listening but are not listed in /bin/netstat through brute forcing of all TCP/UDP ports available. This package can be used by rkhunter in its daily scans. This package is useful for network security checks, in addition to forensics investigations.
unhide
Forensic tool to find hidden processes
root@kali:~# unhide -h
Unhide 20240509
Copyright © 2010-2024 Yago Jesus & Patrick Gouin
License GPLv3+ : GNU GPL version 3 or later
http://www.unhide-forensics.info
NOTE : This version of unhide is for systems using Linux >= 2.6
Usage: unhide [options] test_list
Option :
-V Show version and exit
-v verbose
-h display this help
-m more checks (available only with procfs, checkopendir & checkchdir commands)
-r use alternate sysinfo test in meta-test
-f log result into unhide-linux.log file
-o same as '-f'
-d do a double check in brute test
-u inhibit stdout buffering of subprocesses (needs stdbuf command)
Test_list :
Test_list is one or more of the following
Standard tests :
brute
proc
procall
procfs
quick
reverse
sys
Elementary tests :
checkbrute
checkchdir
checkgetaffinity
checkgetparam
checkgetpgid
checkgetprio
checkRRgetinterval
checkgetsched
checkgetsid
checkkill
checknoprocps
checkopendir
checkproc
checkquick
checkreaddir
checkreverse
checksysinfo
checksysinfo2
checksysinfo3
unhide-linux
Forensic tool to find hidden processes
root@kali:~# unhide-linux -h
Unhide 20240509
Copyright © 2010-2024 Yago Jesus & Patrick Gouin
License GPLv3+ : GNU GPL version 3 or later
http://www.unhide-forensics.info
NOTE : This version of unhide is for systems using Linux >= 2.6
Usage: unhide-linux [options] test_list
Option :
-V Show version and exit
-v verbose
-h display this help
-m more checks (available only with procfs, checkopendir & checkchdir commands)
-r use alternate sysinfo test in meta-test
-f log result into unhide-linux.log file
-o same as '-f'
-d do a double check in brute test
-u inhibit stdout buffering of subprocesses (needs stdbuf command)
Test_list :
Test_list is one or more of the following
Standard tests :
brute
proc
procall
procfs
quick
reverse
sys
Elementary tests :
checkbrute
checkchdir
checkgetaffinity
checkgetparam
checkgetpgid
checkgetprio
checkRRgetinterval
checkgetsched
checkgetsid
checkkill
checknoprocps
checkopendir
checkproc
checkquick
checkreaddir
checkreverse
checksysinfo
checksysinfo2
checksysinfo3
unhide-posix
Forensic tool to find hidden processes
root@kali:~# unhide-posix -h
Unhide-posix 20240509
Copyright © 2013-2024 Yago Jesus & Patrick Gouin
License GPLv3+ : GNU GPL version 3 or later
http://www.unhide-forensics.info
NOTE : This is legacy version of unhide, it is intended
for systems using Linux < 2.6 or other UNIX systems
usage: unhide-posix proc | sys
unhide-tcp
Forensic tool to find hidden TCP/UDP ports
root@kali:~# unhide-tcp -h
Unhide-tcp 20240509
Copyright © 2010-2024 Yago Jesus & Patrick Gouin
License GPLv3+ : GNU GPL version 3 or later
http://www.unhide-forensics.info
Usage: unhide-tcp [options]
Options :
-V Show version and exit
-v verbose
-h display this help
-f show fuser output for hidden ports
-l show lsof output for hidden ports
-o log result into unhide-tcp.log file
-s use very quick version for server with lot of opened ports
-n use netstat instead of ss
unhide_rb
Forensic tool to find hidden processes
root@kali:~# man unhide_rb
UNHIDE(8) System Manager's Manual UNHIDE(8)
NAME
unhide -- forensic tool to find hidden processes
SYNOPSIS
unhide [OPTIONS] TEST_LIST
unhide-posix proc | sys
DESCRIPTION
unhide is a forensic tool to find processes hidden by rootkits, Linux ker-
nel modules or by other techniques. It detects hidden processes using six
techniques.
OPTIONS
Options are only available for unhide-linux not for unhide-posix.
-d Do a double check in brute test to avoid false positive.
-f Write a log file (unhide-linux.log) in the current directory.
-h Display help
-m Do more checks. As of 2012-03-17 version, this option has only ef-
fect for the procfs, procall, checkopendir and checkchdir tests.
Implies -v
-r Use alternate version of sysinfo check in standard tests
-V Show version and exit
-v Be verbose, display warning message (default : don't display).
This option may be repeated more than once.
-u Do unbuffered write to stdout. This option could be useful when
unhide is spawned by another process (e.g. it's used by unhideGui).
-H Provide a slightly human frienlier output. This option adds ending
messages to tests and indicates when no hidden process is found.
TEST_LIST
The checks to do consist of one or more of the following tests.
The standard tests are the aggregation of one or more elementary test(s).
Standard tests :
The brute technique consists of bruteforcing the all process IDs.
This technique is only available with version unhide-linux.
The proc technique consists of comparing /proc with the output of /bin/ps.
The procall technique combinates proc and procfs tests.
This technique is only available with version unhide-linux.
The procfs technique consists of comparing information gathered from
/bin/ps with information gathered by walking in the procfs.
With -m option, this test makes more checks, see checkchdir test.
This technique is only available with version unhide-linux.
The quick technique combines the proc, procfs and sys techniques in a
quick way. It's about 20 times faster but may give more false positives.
This technique is only available with version unhide-linux.
The reverse technique consists of verifying that all threads seen by ps
are also seen in procfs and by system calls. It is intended to verify that
a rootkit has not killed a security tool (IDS or other) and make ps show-
ing a fake process instead.
This technique is only available with version unhide-linux.
The sys technique consists of comparing information gathered from /bin/ps
with information gathered from system calls.
Elementary tests :
The checkbrute technique consists of bruteforcing the all process IDs.
This technique is only available with version unhide-linux.
The checkchdir technique consists of comparing information gathered from
/bin/ps with information gathered by making chdir() in the procfs.
With the -m option, it also verify that the thread appears in its "leader
process" threads list.
This technique is only available with version unhide-linux.
The checkgetaffinity technique consists of comparing information gathered
from /bin/ps with the result of call to the sched_getaffinity() system
function.
This technique is only available with version unhide-linux.
The checkgetparam technique consists of comparing information gathered
from /bin/ps with the result of call to the sched_getparam() system func-
tion.
This technique is only available with version unhide-linux.
The checkgetpgid technique consists of comparing information gathered from
/bin/ps with the result of call to the getpgid() system function.
This technique is only available with version unhide-linux.
The checkgetprio technique consists of comparing information gathered from
/bin/ps with the result of call to the getpriority() system function.
This technique is only available with version unhide-linux.
The checkRRgetinterval technique consists of comparing information gath-
ered from /bin/ps with the result of call to the sched_rr_get_interval()
system function.
This technique is only available with version unhide-linux.
The checkgetsched technique consists of comparing information gathered
from /bin/ps with the result of call to the sched_getscheduler() system
function.
This technique is only available with version unhide-linux.
The checkgetsid technique consists of comparing information gathered from
/bin/ps with the result of call to the getsid() system function.
This technique is only available with version unhide-linux.
The checkkill technique consists of comparing information gathered from
/bin/ps with the result of call to the kill() system function.
Note : no process is really killed by this test.
This technique is only available with version unhide-linux.
The checknoprocps technique consists of comparing the result of the call
to each of the system functions. No comparison is done against /proc or
the output of ps.
This technique is only available with version unhide-linux.
The checkopendir technique consists of comparing information gathered from
/bin/ps with information gathered by making opendir() in the procfs.
This technique is only available with version unhide-linux.
The checkproc technique consists of comparing /proc with the output of
/bin/ps.
This technique is only available with version unhide-linux.
The checkquick technique combines the proc, procfs and sys techniques in a
quick way. It's about 20 times faster but may give more false positives.
This technique is only available with version unhide-linux.
The checkreaddir technique consists of comparing information gathered from
/bin/ps with information gathered by making readdir() in /proc and
/proc/pid/task.
This technique is only available with version unhide-linux.
The checkreverse technique consists of verifying that all threads seen by
ps are also seen in procfs and by system calls. It is intended to verify
that a rootkit has not killed a security tool (IDS or other) and make ps
showing a fake process instead.
This technique is only available with version unhide-linux.
The checksysinfo technique consists of comparing the number of process
seen by /bin/ps with information obtained from sysinfo() system call.
This technique is only available with version unhide-linux.
The checksysinfo2 technique is an alternate version of checksysinfo test.
It might (or not) work better on kernel patched for RT, preempt or latency
and with kernel that don't use the standard scheduler.
It's also invoked by standard tests when using the -r option
This technique is only available with version unhide-linux.
Exit status:
0 if OK,
1 if a hidden or fake thread is found.
EXAMPLES
Quicker test:
unhide quick
Quick test:
unhide quick reverse
Standard test:
unhide sys proc
Deeper test:
unhide -m -d sys procall brute reverse
BUGS
Report unhide bugs on the bug tracker on GitHub (https://github.com/YJe-
sus/Unhide/issues)
With recent versions of Linux kernel (> 2.6.33), the sysinfo test may re-
port false positives. It may be due to optimization in the scheduler, the
use of cgroup or even the use of systemd. The use of the PREEMPT-RT patch
amplifies the occurrence of the problem. This is currently under investi-
gation.
SEE ALSO
unhide-tcp (8).
AUTHOR
This manual page was written by Francois Marier (francois@debian.org) and
Patrick Gouin (patrickg.github@free.fr).
Permission is granted to copy, distribute and/or modify this document un-
der the terms of the GNU General Public License, Version 3 or any later
version published by the Free Software Foundation.
LICENSE
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/li-
censes/gpl.html>.
This is free software: you are free to change and redistribute it. There
is NO WARRANTY, to the extent permitted by law.
Administration commands May 2024 UNHIDE(8)