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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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 ...
2
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3answers
77 views

Postfix master running as root

Does running /usr/lib/postfix/master as a root could cause a security threat ? A fresh installation, gives this : root 11622 0.0 0.0 4792 1432 ? Ss 19:11 0:00 ...
0
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1answer
542 views

ShellShock vulnerability and Java Web Applications

I am running a java webapplication ( Spring 3.2 based) on linux hosts. The linux hosts are vulnerable to the ShellShock vulnerability. Can someone exploit this vulnerabiity on my website ?
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2answers
190 views

“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 ...
11
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3answers
6k views

Shellshock Bash bug on mobile systems

Does the bug in Bash affect Android or iOS mobile systems?
0
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1answer
85 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 ...
2
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7answers
357 views

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 ...
6
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2answers
181 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 ...
38
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6answers
6k 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 ...
1
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1answer
85 views

Implications of Bash history [closed]

I am using Salt Cloud to script my deployments of a small collection of commercial servers. Since it is cheap to get things right the first time, I'd like to avoid obvious mistakes. If I leave my ...
0
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2answers
322 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. ...
1
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2answers
142 views

What's there to harden for a home Unix-box behind Comcast cable modem?

I'm learning that much of the security advice I come across under the "hardening" heading simply does not apply to a single-user home desktop box sitting in a private wireless IPv4 LAN behind a ...
0
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2answers
71 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? ...
0
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1answer
47 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 ...
1
vote
1answer
178 views

What RHSA, RHEA and RHBA stands for in the RedHat Erratas?

Do you know what does RHSA, RHEA and RHBA stands for in RedHat Errata ?
13
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1answer
1k views

Is mosh now recommended by the security experts? (2014)

Mosh has been around for a while now. Although it's claimed to be "a replacement for SSH" by its authors, mosh does actually depend on ssh to do the initial authentication, after which an instance of ...
1
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4answers
125 views

Why can't just any program use his own file-system-access-system?

This may sound stupid for everyone who knows more than me about the UNIX-System and security in software: Imagine you have a program trying to cause harm by deleting files. You just do something like ...
4
votes
1answer
90 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 ...
4
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2answers
83 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
113 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 ...
7
votes
2answers
223 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
votes
1answer
154 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 ...
2
votes
1answer
3k views

Create netcat listener and execute reverse shell in the same script

I'm coding an exploit in python that exploits a command injection vulnerability for a CTF and I'm wondering how could I start a netcat listener and then send the payload to the remote host and once ...
0
votes
1answer
285 views

Would adding root to a group open a security hole?

I have a server for which I have created a cron job "sendalerts" to users. Mind you this "sendalerts.php" should be runnable from two methods (via browser and also via a cron job) So cron's job is to ...
1
vote
1answer
125 views

Notification or report for security problem of unix systems? [duplicate]

I have unix systems(Solaris,Oracle,Redhat vs).I have to control all system for security problem,bugs,patch,vulnerabilities I'm looking for securty information for all security issue After that I'll ...
6
votes
4answers
3k 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
155 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 ...
73
votes
5answers
2k views

How can I protect myself from this kind of clipboard abuse?

Clipboard abuse from websites Many websites use JavaScript or CSS to stealthily insert or replace text in the user's clipboard whenever they copy information from the page. As far as I know this is ...
1
vote
2answers
7k 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 ?
1
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1answer
166 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 ...
3
votes
2answers
241 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 ...
2
votes
1answer
113 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 ...
0
votes
3answers
2k 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
votes
1answer
222 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 ...
4
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4answers
537 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 ...
1
vote
2answers
232 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 ...
6
votes
2answers
747 views

How is the available entropy in /dev/random calculated (or estimated)?

It seems (to a non-expert) that /dev/random is acclaimed to be useable as a source of pure random data. However, I am curious as to the analysis of the file /dev/random. /dev/random is a collection ...
2
votes
1answer
202 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?
6
votes
2answers
364 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
1k 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 ...
2
votes
1answer
1k 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
votes
3answers
234 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 ...
8
votes
4answers
576 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 ...
2
votes
3answers
336 views

unix config scanner / compliance checks

I'm looking for a tool, that scans unix operating systems for configuration issues. E.g. a script that finds PermitRootLogin yes in the ssh config file or with other words: a script that automates ...
18
votes
3answers
1k views

Is passing sensitive data through the process environment secure?

Recently I have been looking for the possibility to pass sensitive information from one process to another (at process startup time) without passing it through the command line or without using a ...
1
vote
1answer
362 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 ...
1
vote
2answers
562 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 ...
4
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1answer
5k views

what does it mean to be setuid root?

I am reading Tanenbaum's Modern Operating Systems 3e. He says "Suppose that the program being attacked [with malicious code] is SETUID root in UNIX (or has Administrator power in Windows). The ...
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2answers
344 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?
-1
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1answer
338 views

What time do dictionary attack take on salted passwords?

I was reading that the designers of UNIX password algorithm used a 12 bit salt to modify the E-table of the unix hashing function (the DES). Supposing i have a system with 2^(24) users? Is that ever ...