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
kernel 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 effect 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.
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 showing 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 function.
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
gathered 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 sourceforge
(
http://sourceforge.net/projects/unhide/)
With recent versions of Linux kernel (> 2.6.33), the sysinfo test may report
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 occurence of the problem. This is currently under investigation.
SEE ALSO¶
unhide-tcp (8).
AUTHOR¶
This manual page was written by Francois Marier francois@debian.org and Patrick
Gouin. Permission is granted to copy, distribute and/or modify this document
under 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/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO
WARRANTY, to the extent permitted by law.