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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how to compile with gcc for another architecture and kernel version [on hold]

I am working on: Linux 3.18.0-kali3-586 #1 Debian 3.18.6-1~kali2 (2015-03-02) i686 GNU/Linux I want to compile a C file using gcc for another Linux system: Linux version 2.6.9-89.EL ...
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2answers
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How to track down and remove Mac malware that is calling out?

Little Snitch periodically brings up a dialog that says: Terminal via node wants to accept an incoming connection from X on port 3000 (remoteware-cl). X are different IPs in eastern europe. A full ...
7
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3answers
162 views

MSFConsole/Kali Linux - gain root access to unix system

I am messing around with Kali Linux, MSFConsole and DVWA (Damn Vulnerable Web Application). I have successfully been able to get into the system (Raspberry Pi) by creating a PHP backdoor and uploaded ...
5
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1answer
137 views

Why require root to be the first entry in /etc/passwd?

Security policies sometimes demand that root be the first entry in the /etc/passwd file. Is there a valid reason for requiring this, or is it just conventional to do so since the root account is the ...
3
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1answer
48 views

Unauthorized file writes on Linux

Suppose my web browser or any other web-connected app has a minor security hole that won't allow an attacker to run code but will allow them to write a piece of text into a text file I own. On a ...
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3answers
132 views

How to detect port scan on SIEM within LAN or same Network?

Let's suppose a host machine in the client environment has been infected and its performing port scanning on other machine within the LAN or same Network without passing through Firewall: On what ...
2
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2answers
202 views

nmap detects opened port but can't connect with telnet

I've made an scan to one single IP with nmap and it reports that the port 65301 is opened, and even it detects that it's maybe the service pcanywhere. sudo nmap -p 65000-65535 -sV x.x.x.x Starting ...
2
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1answer
63 views

explanation of an nmap behaviour

I'm testing some vulnerabilities on a machine which has the port 22333 opened (it's used as the ssh port, and I can connect to it without any problem and the telned command get connected): $ telnet ...
2
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1answer
49 views

Privileges separation over parent/children processes on UNIX systems?

I was scrolling through a Google Research paper related to privileges separation and I felt lost while reading this : In Unix, every process runs within its own protection domain, i.e., the ...
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1answer
26 views

Expand user login in Path - Filter malicious values

I have a function that takes a pathname and substitutes every occurrence of '%u' with a given String. For my scenario this given String is the login that a user/attacker enters via ssh during ...
0
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1answer
71 views

SSL certificate appending

On my Linux server I have a keystore which contains SSL certificates and these certs are going to expire in 20 days. Before expiry of old certs, I have installed new SSL certificates to avoid any ...
2
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1answer
172 views

How to view all SSH authorized_keys for a unix server

How would I view all the authorised SSH clients from a unix server? I know that cat ~/.ssh/authorized_keys shows authorised keys if logged in from root. Can other users set their own authorised keys ...
2
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2answers
167 views

How to remove meta and sensitive data from PDF file?

I've some PDF files generated from different sources (such as web-browser, Photoshop, etc.) on Unix. How do I make sure PDF doesn't contain any sensitive information such as IP address, OS, user ...
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2answers
202 views

Is `arc4random` secure enough?

I need to generate many many initialization vectors and session keys in C++ code. I am wondering if arc4random is up to the task. Last I heard, there are many weaknesses in the RC4 cipher. Should I ...
4
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1answer
101 views

Is symlink race a very common vulnerability in UNIX systems

As far as I know, when I am creating a new file or directory in a directory that can be written by multiple users (and thus an adversary can have made a symlink there), the only way to protect myself ...
1
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1answer
58 views

How do you determine if an open source script contains malicious code?

I am trying to analyze an open source auditing tool to determine if it makes unnecessary and potentially harmful changes to the system. I am interested in determining if the script calls any binaries ...
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0answers
323 views

What is the “crafted DBGCMD_LQUERYLV” in CVE-2014-8904

https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-8904 lquerylv in cmdlvm in IBM AIX 5.3, 6.1, and 7.1 and VIOS 2.2.x allows local users to gain privileges via a crafted DBGCMD_LQUERYLV ...
15
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1answer
826 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 ...
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3answers
678 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 ...
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1answer
589 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
337 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 ...
10
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3answers
6k views

Shellshock Bash bug on mobile systems

Does the bug in Bash affect Android or iOS mobile systems?
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1answer
144 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 ...
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7answers
528 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
242 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 ...
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6answers
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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 ...
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1answer
100 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 ...
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2answers
422 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. ...
2
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2answers
203 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 ...
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2answers
83 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
67 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 ...
2
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1answer
405 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 ?
14
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1answer
2k 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 ...
2
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5answers
159 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
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1answer
113 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
106 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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126 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 ...
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2answers
244 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
175 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
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1answer
4k 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
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1answer
432 views

Would adding root to a group open a security hole? [closed]

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 ...
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1answer
133 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 ...
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4answers
4k 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
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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 ...
104
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5answers
3k 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 ...
2
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2answers
13k 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 ?
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1answer
223 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
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2answers
327 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
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1answer
131 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 ...
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3k 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? ...