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2
votes
1answer
25 views

Setuid, SUID bit not providing root privileges

I've written and compiled a short program to allow any user to change the contents of my /sys/class/backlight/intel_backlight/brightness file, but I fail to escalate their permissions. What could I be ...
-3
votes
2answers
38 views

How can I identify if a binary file is set-user-ID? [closed]

In Linux, how can I identify if a binary file is set-user-ID? Can I use ls -l?
1
vote
1answer
62 views

Difference between owner/root and RUID/EUID

I am relatively new to the concepts mentioned in the question and reading about them from different sources only makes them more confusing. So this is what I understood so far: When we are given ...
0
votes
1answer
17 views

Not able to write a file when in the same group using PHP posix_setuid()

I'm running a PHP process from root which calls posix_setuid(1500); and then tries to open a file output.log The ls -l output.log shows this output: -rwxrwxr-x 1 www-data www-data 2294376 Mar 19 ...
0
votes
2answers
34 views

Why is the suid bit having no effect on a shell or perl script? [duplicate]

As an experiment in playing with the suid bit, I tried writing a script to run apt-get update from a bash script, and then set the suid bit on it, so I could just run ~/update or something. apt-get ...
0
votes
5answers
53 views

setuid (and other) permissions lost when copying / elsewhere - what to do?

I sort-of-cloned an existing Debian 7.x distro by copying the contents of the root filesystem (not the special dirs of course) to another HDD. I booted, things seem to run, but - I get some weird ...
2
votes
2answers
62 views

linux setuid does not work

I am learning linux suid,so I have written a small c program with the following content to test it #include<stdio.h> int main(){ system("echo 100 >> test.txt"); return 0; } -rwsr-xr-x 1 ...
-1
votes
2answers
38 views

Adding setuid permissions to a file

I am hosting a php application on my CentOS 5 server. The application runs some commands via a ssh file called openmgr. For that I want to give a permission of -rwsr-xr-x to the file. I tried chmod ...
0
votes
0answers
12 views

Running a script with elevated privileges [duplicate]

I need to find a way to run a script with elevated privileges but without compromising security. One suggested that i should use setuid but i don't think that is an option since it can cause serious ...
0
votes
1answer
123 views

How to enable a non-root user to empty the linux buffer cache

I'm required to empty the linux buffer cache in a python script, that runs on a Debian wheezy VM. As root I run sync; echo 3 | sudo tee /proc/sys/vm/drop_caches, but the script is run by a user, ...
0
votes
1answer
164 views

crontab not executing my script?

I added this rule to the bottom of my crontab * * * * * /root/test.sh It basically resets iptables so I can fool around. If I mess up I won't be locked out of my box. When I run the script in bash ...
2
votes
1answer
53 views

Security of capabilities vs setuid (LD_PRELOAD, etc)

I know that if a process is run setuid that it's protected against various things that could subvert the process, like LD_PRELOAD and ptrace (debugging). But I haven't been able to find anything on ...
17
votes
2answers
1k views

Using the setuid bit properly

I have a process that needs root privileges when run by a normal user. Apparently I can use the "setuid bit" to accomplish this. What is the proper way of doing this on a POSIX system? Also, how ...
2
votes
2answers
207 views

print the /etc/shadow file in the console

How do I change the permissions of an executable file to access the /etc/shadow file? So far I have the following bash script: #!/bin/bash gcc print.c -o print chmod +s print ./print exit 0 and ...
1
vote
2answers
158 views

Why the S_ISUID and S_ISGID mode bits got cleared when the owner or group of an executable file are changed by an unprivileged user

I was reading the man page of chown. I don't understand why S_ISUID and S_ISGID mode should be cleared when the function returns successfully.
2
votes
2answers
176 views

what is the purpose of setuid enabled with no executable bit?

I am trying to understand permissions in detail. I was reading about setuid and it's uses. However, this particular case confuses me. I have made a small script and now I have set the suid bit for ...
1
vote
1answer
150 views

SUID-bit not working for executables within /tmp directory

Printing the value of getuid() and geteuid() from an executable with SUID-bit (chmod +s) turned-on, seems to result with the original caller ID instead of the owner id if the executable is located ...
2
votes
2answers
86 views

Why does FreeBSD require terminal programs to be started as root?

On FreeBSD all graphical terminal programs (e.g. xterm, rxvt) seem to be installed setuid root, or with setuid root wrappers. On Linux, this is not the case on any distribution I have ever used. Why ...
3
votes
1answer
127 views

Why doesn't Ubuntu use capabilities on ping?

After running, $ ls -l /bin/ping -rwsr-xr-x 1 root root 34740 Nov 5 2012 /bin/ping I wonder, why doesn't Ubuntu use capabilities (i.e. raw sockets) rather than setuid?
1
vote
2answers
757 views

Why setuid does not work on executable?

I know that enabling setuid on scripts has security issues and so is inactive by default, but expect that it works for executables. I created and executable which shows uid as an output following ...
2
votes
3answers
911 views

File permission with setuid and octal 4000

When we set setuid to a file, we do the following in the terminal: chmod u+s filename This works fine. But the octal number 4000 is always associated with setuid (in books etc). I understand (to ...
1
vote
1answer
86 views

Apache suexec won't work with strace

I have an Apache instance with mod_suexec enabled. I'm trying to debug a problem and am starting Apache with strace to try and see what's happening. However, when I start Apache like this: # strace ...
2
votes
1answer
65 views

Why isn't 'nethogs' installed with the setuid bit set?

I've been using nethogs for a while now, having to sudo every time, while ping has the setuid bit set. Today I set it for nethogs and it works: $ ls -l $(which nethogs) $(which ping) -rwxr-xr-x 1 ...
1
vote
0answers
75 views

Limit program execution to a list of arguments

I would like that my Unix users can only run a specific command insecurecommand with a controlled list of arguments stored in a file. The only solution I have found at this time is to : Create a ...
2
votes
3answers
1k views

How do I drop root privileges in shell scripts?

The "--up" option in OpenVPN is normally used for routing etc. And so it is processed before OpenVPN drops root privileges to run as nobody. However, I am invoking shell scripts that need to run as an ...
3
votes
1answer
660 views

Why doesn't setuid not work? [duplicate]

I want my program can only be run by user xyz using root privilege. So I set setuid with: chmod u+s program1.sh ls -l program1.sh rwsr-x--- 1 root house 1299 May 15 23:54 program1.sh And I let user ...
2
votes
1answer
238 views

Using setuid Properly

I've been scared too much by the warning about setuid. However I cannot find a way around using it. I want to be able to run: arp -s 198.51.100.1 00:53:00:12:34:56 as the user steven but arp -s ...
5
votes
2answers
901 views

Group memberships and setuid/setgid processes

Processes which de-escalate privileges via setuid() and setgid() do not seem to inherit the group memberships of the uid/gid they set. I have a server process that must be executed as root in order ...
3
votes
1answer
756 views

How to let a user execute a script owned by root? Setuid doesn't seem to work anymore [duplicate]

I have some bash scripts that I use with the user 'root' to manage iptable rules. The problem is that I want these things at the same time: The script must be owned by root Permissions must be 700 ...
3
votes
2answers
218 views

using SUID bit to drop privileges

So this is a description of the system I'm working on : a "manager" process spawns all the other applications. The manager application runs as root user. so now, any process that it spawns also ...
1
vote
1answer
130 views

Principle of least privilege: Does Authbind helper really need setuid root, or can it run with cap_net_bind_services?

Does Authbind's helper really need setuid root, or can it run with the CAP_NET_BIND_SERVICES capability and still work?
2
votes
2answers
157 views

set umask (permissions) similarly as setgid on a directory

I know how to use setgid on directories, to enforce that whole directory structure has uniform user:group ownership. Is there a similar way to set the umask for a directory, so that the whole ...
1
vote
1answer
104 views

Why doesn't setuid on /sbin/dhclient work as intended?

I am the only user on my machine, and prefer not to type sudo every time I use dhclient. Therefore, I tried sudo chmod u+s /sbin/dhclient. However, when I subsequently run dhclient wlan0 from a ...
6
votes
3answers
325 views

Under what scenarios would I want to set a SUID bit?

I'm struggling to wrap my mind around the concept of SUID bits and why they're would be useful. For example, let's say I have a program: -rwsr-xr-x 1 root root 12364 Jan 12 2013 ...
2
votes
0answers
61 views

LXC: Have rootfs mounted without nosuid

I have the container's rootfs in a volume mounted with the nosuid option. When I start the container, its / mounted is then also mounted nosuid, which breaks programs such as sudo. How can I avoid ...
5
votes
2answers
3k views

Setuid bit seems to have no effect on bash

I was experimenting a bit and noticed something strange: setting the setuid bit on a copy of bash located at /usr/bin/bash-test seemed to have no effect. When I ran an instance of bash-test, my home ...
3
votes
1answer
100 views

how to record command which execute a programme suid

My question: Is there a way to record all commands who execute a suid programme? Like what .bash_history do, but only the setuid programmes.
3
votes
1answer
262 views

How does having /dev/fd make running shell scripts under sudo safe?

At the end of the man page for sudo, there's the following remark: Running shell scripts via sudo can expose the same kernel bugs that make setuid shell scripts unsafe on some operating systems ...
26
votes
1answer
633 views

What would be the best way to work around this glibc problem?

I administer a Gentoo Hardened box that uses file capabilities to eliminate most of the need for setuid-root binaries (e.g. /bin/ping has CAP_NET_RAW, etc). Infact, the only binary I have left is ...
1
vote
1answer
1k views

How to suid iwconfig on Debian wheezy?

I have a script running under my own user account that takes care of all sorts of wireless interfaces. It (more or less) intelligently switches wireless LAN off and on and so forth. However, it does ...
2
votes
1answer
246 views

How to set up a script to run as root non-interactively?

I need to set up the following script to run as root whenever I log in: #!/bin/zsh truncate -s 0 ~yourstruly/.juniper_networks/network_connect/ncsvc.log I know how to run the script as root ...
2
votes
2answers
571 views

setuid programs don't seem to run setuid in TinyCore Linux

I want to demonstrate the vulnerability of setuid programs using the TinyCore Linux live cd. That is, I craft a special program, with special permissions, so that it runs as the owner of the file ...
4
votes
2answers
1k views

Purpose of using setuid() in SUID programs

I wonder that an SUID program like passwd is using the setuid() function call. Why does it drop root privileges? Against what types of attack does this help? Buffer-overflow?
4
votes
1answer
651 views

Clear setuid permission using numeric mode

On an Ubuntu Linux I have a directory with the setuid bit set (drwsr-xr-x) which I want to unset. Neither chmod 755 nor chmod 0755 nor chmod 00755 (I though maybe the first 0 is interpreted as just ...
2
votes
3answers
4k views

How does the set-user-ID mechanism work in Unix?

Can someone please explain the set-user-ID mechanism in Unix ? What was the rationale behind this design decision? How is it different from effective user id mechanism ?
3
votes
1answer
923 views

How to replace setuid with file-system capabilities

Inspired by this question here is the follow-up: As some of you may know setuid-binaries are dangerous, since some exploits use these to escalate their rights up to root. Now it seems that there has ...
3
votes
2answers
1k views

setuid and setgid confusion

I'm trying to fully grasp the concept of setuid and setgid, and I'm not quite sure in what way permissions are actually elevated. Let me provide an example: Users userA (groups: userA groupA) userB ...
5
votes
1answer
656 views

root owned program with setuid bit on

Ping is a a program owned by root with the user id bit set. $ ls -l `which ping` -rwsr-xr-x 1 root root 35752 Nov 4 2011 /bin/ping As I understand it, if a user runs the ping process, then the ...
4
votes
1answer
594 views

Environment settings on setuid executables

I am observing a curious behavior when running a program with setuid bit enabled. Program foo is owned by user bar with setuid bit set. User execbar runs foo foo reports that one of the dynamic ...
3
votes
1answer
176 views

Running setuid binary temporarily without setuid?

Currently setting up xpra, which wants to run an X instance as non-root using the dummy driver, but the system Xorg binary is SUID. Since the system auto-updates, I would prefer not making and ...