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 secure is it to use secret directory names to share files on unix?

There is an old trick on unix systems to allow a non-root user to "securely" share files with particular other users. mkdir share chmod 711 share #others can traverse share, but can't list its ...
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2answers
150 views

sharing private key sTunnel

All of the sTunnel guides and implementations at work do the same thing, they say once the private key and the public cert are created on the server, you need to cat them together and then share with ...
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1answer
18 views

What is the rationale for calling setgroups on a list of length one?

The Secure Programming Cookbook for C and C++ says that: "Ancillary groups are inherited by a process from its parent process, and they can only be altered by a process with superuser privileges. ...
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1answer
147 views

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

I have Unix systems (Solaris, Oracle,.Redhat etc.). I have to control all systems for security problem,bugs,patch,vulnerabilities. I'm looking for security information for all security issues. After ...
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2answers
762 views

Can UNIX Domain Sockets be locked by user ID?

If I created a folder /tmp/me with permissions 700, and started a process under me that starts a listen socket under /tmp/me/socket. I currently assume that a connection to that socket originated ...
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2answers
278 views

Security of o=rwx with classical Unix permissions

Is it in anyway insecure to go o=rw or o=rwx on files and directories confined to directories that are marked o=? In other words, given private (g=,o=) home directory, is it perfectly safe to write ...
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2answers
1k 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 ...
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1answer
36 views

Are path traversals attacks possible with invalid directories between?

Let's say I can control the variable $path and the full path is generated as follows: $full_path = "./valid_dir/docs/" . trim($path) ; readfile($full_path) ; where docs a non existent dir in the ...
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2answers
537 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 ...
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1answer
33 views

Always setgroups before setuid?

On GNU/Linux systems that are build using RPM packages, the rpmlint utility complains about programs that don't call setgroups before setuid. The idea is that before dropping privileges, a process ...
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0answers
65 views

Default accounts shutdown, halt, and sync - still shipping?

I'm curious as to whether, and if so why, Unix and Linux distributions still ship with default accounts shutdown, halt and sync. Specifically (from a Red Hat document), sync:x:5:0:sync:/sbin:/bin/...
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61 views

Integrated Windows Authentication and Java/Unix

I have a specific scenario where we have existing ASP.NET Web applications/services hosted in IIS and accessible via Integrated Windows Authentication. The challenge is to have a new web application ...
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5answers
4k views

Why should one use sudo? [duplicate]

Most modern Linux articles advice using sudo rather than logging into root. This advice is so ingrained, some distros don't automatically allow root login. Indeed they come pre-configured with sudo ...
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4answers
7k views

OpenBSD vs. NetBSD security

If I search for the two words: OpenBSD and NetBSD on http://www.exploit-db.com/ then I get 17 hits regarding security bugs on OpenBSD, and 8 hits regarding security bugs on NetBSD. So what are the ...
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1answer
522 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 ...
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4answers
731 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 ?
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2answers
5k 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 ...
126
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5answers
5k 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 ...
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2answers
3k 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 ...
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5answers
3k views

Is it possible for a file that is non-executable and read-only to run malicious code?

On a POSIX system, is there a possibility for a file which is non-executable and read-only (aka with a mode 444) to run malicious code on a machine? If so, can you explain how it would do so?
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2answers
2k views

Can you describe a real-life scenario of exploiting sticky bits?

Sticky bit are mentioned in every UNIX security book, but I couldn't find anyone that describes the exploitation of Sticky Bit set on a file. Can you?
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1answer
108 views

Should I compile as root?

When I am compiling software for local installation, what factors should I take into consideration when deciding whether to compile as root or to compile under my regular user account? ./configure ...
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3answers
2k 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 ...
3
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1answer
86 views

How to recover/log attempted passwords from a failed login [closed]

I saw the following question before: Is it legal to log passwords from failed logins? I think it raises another question: How do I log failed attempted passwords? That seems very useful when I need ...
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0answers
86 views

Pentesting - is there a way to check file permissions on linux remotely - KALI

I'm trying to modify a PHP file through a plugin on wordpress. Everything goes well, but I had to modify the permissions to 666 manually via terminal on the victim's machine, cause even when I'm ...
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1answer
193 views

What is the entropy of a password made with pwgen?

pwgen is a unix utility that generates "memorable" passwords randomly. The man page says the entropy is lower than truly random passwords with the same specification. What is the actual entropy of a ...
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2answers
64 views

Is it safe to expose a logging socket endpoint in a chrooted environment?

I'm trying to set up a file transfer server, which needs to be secured and logged. FTP was suggested, but that feels outdated so I automatically translated that to SFTP (OpenSSH) in my head. Using ...
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3answers
2k views

Why are people saying that X-windows is not secure?

Why are people saying that X is not secure? By X I mean: https://secure.wikimedia.org/wikipedia/en/wiki/X_Window_System The OpenBSD team succeeded with privilege separation in 2003; why didn't the "...
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2answers
212 views

How to track down and remove Mac malware that is calling out? [duplicate]

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 ...
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3answers
944 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 ...
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1answer
162 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
59 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
13k views

Finding environment variables with gdb, to exploit a buffer overflow

I have to exploit a very simple buffer overflow in a vulnerable C++ program for an assignment and I am not being able to find the environment variable SHELL. I have never worked with BoF before, and ...
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2answers
959 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
119 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 ...
3
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1answer
107 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
32 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 ...
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1answer
78 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 ...
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0answers
395 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 ...
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2answers
408 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 name,...
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2answers
481 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 ...
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1answer
628 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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4answers
750 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 ...
1
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1answer
86 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 ...
2
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5answers
229 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
8k 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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1answer
954 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
2k 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 /usr/lib/postfix/...
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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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2answers
534 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 ...