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.

       -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 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 GitHub (https://github.com/YJesus/Unhide/issues)
       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 occurrence 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
       (patrickg.github@free.fr).
       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.