--- name: "unhide-linux26" section: "8" platform: "linux" package: "unhide" version: "20110113-4" release: "Debian 7 (Wheezy)" platforms: ["linux"] url: "https://new.carta.tech/unhide" --- # unhide-linux26(8) forensic tool to find hidden processes Part of [unhide(8)](/unhide/8.md). ## NAME unhide — forensic tool to find hidden processes ## SYNOPSIS **unhide** \[*OPTIONS*\] *TEST\_LIST* ## 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 - **-f** Write a log file (unhide.log) in the current directory. - **-h** Display help - **-m** Do more checks. As of 2010-11-21 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. The *checkproc* technique consists of comparing /proc with the output of /bin/ps.\ This technique is only available on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. 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 on Linux 2.6 kernels. ### Exit status: - 0 if OK, - 1 if a hidden or fake thread is found. ## BUGS Report **unhide** bugs on the bug tracker on sourceforge (http://sourceforge.net/projects/unhide/) ## 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 \.\ This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.