Questions tagged [unix]

Unix is a family of multiuser, multitasking operating system that is widely used in workstations, servers and embedded devices. The best-known Unix variant is Linux.

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15
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1answer
2k views

Linux /etc/shadow password change security

I wonder what happens what happens when I am changing my password on a Linux system. Basically all passwords are stored in a file called /etc/shadow or /etc/master.passwd in BSD-like systems as I do ...
11
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3answers
7k views

Shellshock Bash bug on mobile systems

Does the bug in Bash affect Android or iOS mobile systems?
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2answers
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"Shell shock" - exploitable when `system()` syscall or `exec(bash)`, right?

Is my understanding correct that in order to exploit via "Shell Shock", binary we influence needs to execute bash (and we need to have influence on command line)? Therefore, am I correct, that if ...
0
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1answer
515 views

Detecting port scans in OSX kernel

Is it possible to detect port scans on OSX at the kernel level? I would like to write a kext that detects the ip addresses of systems scanning my computers ports. How exactly does a stealth scan work?...
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7answers
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Is it wrong to root login with SSH?

I've long been under the impression that with unix, you should never login as root. Now I've started using Virtual Private Servers over at DigitalOcean, and some advice is to use SSH keys to login as ...
7
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2answers
790 views

Where can I “hide” easter eggs for students learning about Linux security?

I feel like this isn't the best place to ask this (since there's no single right answer), but I can't think of a better place. If you have a better recommendation, could you please recommend it and I ...
61
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6answers
29k views

Unix execute permission can be easily bypassed. Is it superfluous, or what's the intention behind it?

The unix read permission is actually the same as the execute permission, so if e.g. one process has write access it's also able to execute the same file. This can be done pretty easily:First this ...
0
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2answers
695 views

Given an IP address can you ssh into /tmp without password?

I'm a Software Engineer, but I have no experience in security, so i'm trying to learn by doing (woot Experiential learning!). I know that the permission settings on the tmp folder are very relaxed. ...
0
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2answers
206 views

Creative vulnerabilities in unix eval command [closed]

I'm reading through past exams for an information security subject and I came across this. #!/bin/sh #applications launcher X=$1 eval "$X" "Do you think the program is vulnerable to attacks? Explain ...
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1answer
111 views

Identity theft from ubuntu machine? [closed]

Recently my debit card information went to another hand, and he/she started to using it until my bank reports that there is an overdraft. I use Ubuntu 14.04 machine. I am sure I am not a victim of ...
3
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2answers
422 views

OBSD X11 as non-root?

If running X11 as root is not a very good idea, then can anyone mention a method/solution, how to still use a GUI, and not having X11 as root?
1
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1answer
386 views

Do I need logging enabled in my rules in IPFW for sshguard-ipfw to work/blacklist ip's?

From the FreeBSD handbook: Even with the logging facility enabled, IPFW will not generate any rule logging on its own. The firewall administrator decides which rules in the ruleset will be logged, ...
4
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1answer
183 views

Dangerous to open a unix socket within www root?

My web server is chrooted into /var/www, and its contents are available over the network. One of my web applications needs access to a unix socket, and so that socket needs to be somewhere in /var/...
4
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2answers
184 views

What are the benefits of having multiple overwriting patterns for secure deletion? [duplicate]

When installing a new AIX server, there is a possibility to use several patterns for secure deletion. My question: Is it necessary to use several patterns? What is the benefit from having several ...
3
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0answers
208 views

BSD encryption advantages [closed]

If someone who knows about the BSD project has a moment to answer this, I'm wondering a few things about the encryption used. It's more than what I'm finding in the docs and on Wiki/Google (even the ...
5
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1answer
713 views

OpenBSD-based LiveCD/LiveDVD - is it secure? is it offical?

Does the OpenBSD LiveCD/LiveDVD get deeply audited like the original OpenBSD? Is it an official "port"? Experiences with it?
7
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2answers
318 views

What output can a program, when executed from a command line, output to generate behavior that is a vulnerability on the terminal emulator?

Reading this post, titled "Fixing Unix/Linux/POSIX filenames", I came across a VERY interesting phrase by the author, which says: Oh, and don’t display filenames. Filenames could contain control ...
3
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1answer
315 views

S/Key as an alternative to UNIX passwords

There is this password system called S/Key I saw on the Internet. Can someone give me a brief description about S/Key and how it works? Can S/Key be an alternative solution to the UNIX password system?...
2
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1answer
231 views

Eavesdropping a communication between a local application and the network

After some digging on the Internet, I've been unable to find a satisfying solution for my curiosity... Here's the thing : using a shell script, I've been able to obtain a list of IP addresses ...
8
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4answers
9k views

SHA-512 unix passwords. How secure are those hashes, really?

I came across this very alarming sounding thread which indicates a GPU with about half the compute capacity of the GPU currently powering the monitor I type this on is capable of 11.5k c/s. I'm not ...
5
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2answers
308 views

What is the meaning of the term "simple string" for the SALT string in Unix crypt using SHA-256 and SHA-512?

In Unix crypt using SHA-256 and SHA-512 the author, Ulrich Drepper, introduces the SALT string as the following (highlight by me): For the SHA-based methods the SALT string can be a simple string ...
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2answers
122k views

Where is my password stored on Linux? [duplicate]

Is there a specific location where the passwords are stored ? Is it depending on which version is used ? Are they salted ?
3
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2answers
812 views

Does glibc2 version of the crypt function still use DES for alternative hashing methods?

I'm trying to understand how typical Linux distributions generate the password field for entries in /etc/shadow. I can't figure out what encryption algorithm is being used to produce the encrypted ...
18
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3answers
32k views

How do I ensure data encryption on Samba transmission on *NIX systems?

I have a heterogeneous system (both MS and *nix) that communicates with CIFS/SMB. How can I ensure proper data encryption at the application layer?
4
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3answers
7k views

Are file permissions set in Unix/Linux effective in Windows or Any other OS?

Consider some files and folder in Unix/Linux OS which are configured for only read access by root, if the hard drive stolen, and used in Windows Environment, are these permissions are still effective? ...
2
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2answers
755 views

What's the secure way to change UNIX permissions on a harcoded file often?

I'm writing a daemon that monitors something in the OS and flips execution permissions on a file in /run/ back and forth. The file has static contents and the file name is hardcoded in the daemon. I ...
2
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1answer
297 views

unix malicious scripts/ksh execution

I'm wondering whether my architecture poses a security risk. Details: The whole website is not ROOT owned but still, the APACHE user used instead has some pretty advanced permissions. I have a folder ...
4
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4answers
2k views

What mechanism enforces user permissions in Unix/Linux?

One of the core pieces of security in Unix/Linux systems is limiting privileges by user. For instance, certain actions can only be done by the root user. In theory, this can keep a malicious process ...
2
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1answer
287 views

is root@localhost the same as Unix root with GUID = 0 and ID = 0?

Is a Mysql root user (root@localhost) the same as the computer root account (GUID = 0, ID = 0) ? I mean, is it the root which is executing the script? How can I know if the users are the same?
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2answers
853 views

How a malware executes remote payload

Let's assume a malware was installed (on a UNIX-based platform) with some social engineering tricks. The original installed code itself may be benign, but the only malicious activity is that the ...
3
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5answers
4k views

Security purpose of asking admin password to mount partition on Linux

So I divided my 250GB laptop drive into 2 partitions and some swap. On the second partition which is an ext4 60GB partition I installed Fedora 17. On the other bigger NTFS partition I've got Win XP ...
3
votes
1answer
2k views

Is the mount manpage saying nosuid *is* secure, or is *not*?

I'm a bit confused about the description of nosuid in the mount manpage on this RedHat system I'm setting up: nosuid Do not allow set-user-identifier or set-group-identifier bits to take ...
5
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3answers
303 views

Could browsers improve security of stored passwords by using setuid?

On Unix-esque systems, Mozilla Firefox stores a users' preferences, web history and stored passwords in a set of files that are readible and writeable by that particular user. This makes sense: when ...
10
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4answers
2k views

Does UNIX have a dual approval mechanism?

Sudo and logging is used to keep administrators accountable. But is there a command/configuration that lets you enforce a dual approval type control such as the the "Two Person Concept"? (eg. Two ...
1
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1answer
714 views

Installing applications with different user accounts on linux

I have basic question about installing applications on Linux operating system, using the Oracle database as an example. When installing the Oracle database package, I created a user called ora112, a ...
4
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2answers
1k views

Security issues with an append-only log in UNIX

I'm going over past exam papers for a security module I'm taking at university and there is a question which I can't give a great answer for. As a security manager in a bank you are asked to ...
2
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2answers
743 views

Why superuser or administrator account should never locked?

Why should administrator or superuser account never locked regardless how many incorrect login attempts are made? What should be done instead to alert the staff to the attempted instrusion?
3
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2answers
2k views

vulnerable getlogin

I was reading "A taxonomy of Coding Errors" and I have a doubt regarding the point mentioned in C/C++ >> API Abuse >> Often Misused: Authentication(getlogin). I fail to understand the attack vector ...
97
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7answers
38k views

How does hacking work?

I am specifically talking about web servers, running Unix. I have always been curious of how hackers get the entry point. I mean I don't see how a hacker can hack into the webpage when the only entry ...
12
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2answers
5k views

What are the dangers of storing webserver temp files in the /tmp/ folder?

I have configured my first publicly accessible nginx server. I have configured it to use a /tmp/nginx folder to store temp files. This includes the body of http requests, proxy files etc. The /tmp ...
5
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3answers
4k views

Making passwd/shadow files more secure

The passwd/shadow files in a unix-like OS contain sensitive info such as a user's password. In addition those files aren't necessarily secured: with a live CD we can access those files on the hard ...
1
vote
1answer
3k views

Can Solaris' shadow hashes be created by better algorithms than the default DES-based hash?

By default, Solaris uses Traditional DES to encrypt password hashes in the shadow file. Is there a way to harden the security by changing this default behaviour and make it to be hashed using a ...
2
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3answers
665 views

Security Implications of setting passwd as suid

When the passwd command is executed, it runs as the root user. Can't this be exploited? If not, why?
7
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3answers
254 views

Is it safe to attach a potentially malicious hard drive to a Solaris machine?

We bring in hard drives from un-trusted sources and would like to ensure that they will not contain any harmful content. What kind of risk is there for Solaris? As in, if Solaris is running, and I ...
2
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2answers
716 views

Sun ILOM / Out of band management security concerns

I would like to get some outside opinion on this if possible, although I do not know what to ask. Sun ILOM is an Out-of-band management system. I understand it is a separate OS on the box that is ...
11
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3answers
633 views

Is it insecure to have an SSH server on a workstation?

I know one systems administrator who runs SSH Server on his workstation to push files to it and check things from a phone but I think it is a bad idea for several reasons: An operations workstation ...
14
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7answers
735 views

UNIX Servers: Possible intrusions or attacks that do not use any of the open listen sockets

What type of attacks are there that do not use open TCP or open UDP ports? Is it safe to assume that no open ports means no remote access? (Excluding the possibility that there is a badware already ...
6
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2answers
437 views

How is the password prompt going to protect me from ruining my computer?

On Unix based systems, I'm often prompted to enter my password before installing or running a program. Why does this protect me? If I'm running a kiosk, I understand that a password might prevent ...
10
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1answer
325 views

What is your default umask set to?

What is your default umask set to? Did you run into any problem setting a stricter default umask?
11
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3answers
2k views

What prevents this exploit from working (unix SUID)?

If I have a user on a unix system where Im allowed to create new files, what prevents me from downloading an executable file onto that system which is already SUID'ed to root on a different system? ...

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