Securing Linux systems and applications; understanding Linux security features.

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How important is a static IP address when authenticating with my server?

I am looking to move my business into a small office. I have found somewhere very suitable but unfortunately they cannot provide a static IP address. Currently, to connect to my server from home I ...
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3answers
51 views

How secure are webservers from linux repos?

how secure are Webserver like Apache2 or Nginx on a current linux, e.g. Debian, when downloaded from a repo of this distro? Of course, they have to configured correct and must be up to date. If they ...
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21 views

What is purpose of fipscheck utility and fipscheck library on Linux?

So I am messing around with dracut and I am trying to get my Linux system in FIPS 140 mode by passing fips=1 to my linux kernel at the boot time from grub. However, I got confused on why dracut ...
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29 views

How crypto module integrity checks mandated by FIPS 140 standard help to make Linux based appliances safer?

After browsing dracut and hmaccalc rpm package source code I found out sha512hmac utility that is used to do do integrity checks for linux kernel (and other binaries) from initramfs boot stage uses ...
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52 views

How can I understand this extract, concerning basic heap overflow?

Unfortunately, I dont seem to understand one minor concept in the "Art of Exploitation" book, concerning heap overflow: a new root shell is being added to the passwd file. From page 168: However, ...
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19 views

Does altering the routing table to my hub defeat the purpose of a VPN?

I am running a VPN on my server with openvpn. When running openvpn I have a shell script that runs afterwards: ip rule add from 192.168.0.19 table 128 ip route add table 128 to 192.168.0.0/24 dev ...
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5answers
79 views

Is it beneficial to run the browser from a different user account for personal devices?

On Linux, when launching the browser does it help security if I don't run it from my main user (not root, but still has my personal information in it) as follows: su FirefoxUserName -c 'firefox' ...
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42 views

Error Running command shell :TimeoutError Operation Time out

I am Testing a Payload linux/x86/meterpreter/reverse_tcp in my Test Linux network to Exploit, I got a Meterpreter Session by Metasploit using it, I tried several commands like getuid, cat and all ...
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3answers
156 views

How can I execute shell in this CTF exercise?

I am playing a CTF wargame and unfortunatley got stuck at this level, so I want to "crowdsource" it. No need for complete answer, but hints would be enough. How can I: Make strcmp to be 0 (evaluate ...
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2answers
151 views

Is there a reason why /proc/interrupts is world-readable?

Reading this recent research paper on how to use information from /proc/interrupts to attack a system, I was wondering whether there is a particular reason why /proc/interrupts is world-readable. ...
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58 views

Why isn't ettercap working

I am working on an ARP poisoning/browser redirection project with Ettercap but even if I follow all the steps right it still doesn't work. I tried disabling firewalls too. What I do is: Start ...
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1answer
231 views

Air-gap implementation for personal computer use

I recently read over Bruce Schneier's article on setting up an air-gapped computer and am looking to improve my setup (compared to my current "use one Windows PC for everything" model). The main ...
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70 views

Safe to connect a USB to Linux?

A "friend" offerred me a USB with files. I plugged it into my Ubuntu (version 12 or 14, don't remember) PC and an error appeared (don't remember exactly what was written..). So I wasn't able to browse ...
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1answer
27 views

Using virtual server for backing up files

I've purchased a virtual server which I need to run some custom tools every once in a while. I actually don't use any server features of my virtual server, I really just need a Linux machine which is ...
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1answer
43 views

How are DNS requests sent when using ovenvpn? Are they encrypted?

I use openvpn in thru the gnome network manager. When my computer is connected to the vpn do DNS requests look like they come from the vpn exit ip or from my real ip? Are the DNS requests sent in the ...
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1answer
105 views

Hidden service security SSH

Pretend I have a Tor hidden service. For ultimate security I would firewall the internet entirely, except for Tor, to try to reduce IP address leakage and other security risks. My problem is how ...
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58 views

Why there is no shell prompt by exploiting this script?

I tried to get a shell prompt in the following vulnerable code, I think that I found the vulnerability, actually it is a simple stack buffer overflow, but now I have a problem with exploiting the ...
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33 views

Process of auditd -s enable/disable persists for a long time

I have setup auditd on my system, with some basic rules from CIS Benchmark paper and the following auditd.conf file: log_file = /var/log/audit/audit.log log_format = RAW log_group = root ...
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Can we trust the information displayed by the linux utility commands for a vulnerable machine?

After checking a vulnerable linux machine for rootkit and deleting them, we need to get some informations about the process , port ,incoming or outgoing connections... , using some useful commands as ...
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110 views

How does this privilege escalation vulnerability on Elastix work?

Here is a privilege escalation vulnerability on Elastix: # id # uid=100(asterisk) gid=101(asterisk) # sudo nmap --interactive # Starting Nmap V. 4.11 ( http://www.insecure.org/nmap/ ) # Welcome to ...
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1answer
48 views

Is there a functional difference between `chage -M 99999`and `chage -M -1`on Linux?

My group just requested a security scan on some of our development systems and were informed that a number of system type accounts were insecure because the password did not have a maximum time limit. ...
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2answers
446 views

How to prevent the latest ImageMagick vulnerability?

According to the CVE-2016–3714 there are a some vulnerabilities in the ImageMagick program (4 packages) : Insufficient filtering for filename passed to delegate's command allows remote code ...
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3answers
96 views

Mutual authentication of SFTP server

We can use public/private key pairs for client authentication when connecting to a SFTP server. Can we also have mutual authentication so the client also verifies a public key from the server? Both ...
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31 views

Can linux cgroups and namespaces assist hiding malware?

Reading about sandboxing/security possibilities I was looking a bit into cgroups and namespaces and asked myself: How do I know that my linux root account is indeed the real root account and not ...
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1answer
139 views

Raspberry Pi IDS/FireWall - Should I? [closed]

I was excited to setup an IDS/FireWall with my new Raspberry Pi on a standard home network. Reading threats to SSH and Linux, now I am not so sure. Setup by an experienced amateur I'm now concerned ...
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1answer
143 views

Is it possible to use the Linux “echo” command maliciously?

While testing a web application today, I came across a function that passed arguments to dig in linux terminal. After some fiddling about I was able to pass the echo command using pipes and echo my ...
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Is VLC on Linux vulnerable to an attack from .wmv files designed to install viruses? [duplicate]

I was stupid and did not check a video file I downloaded from an untrustworthy source. It was .wmv file with no readable properties of the video. I know that .wmv videos can download viruses. What I ...
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165 views

Prevent keyloggers on Linux?

Are there any mechanisms in the Linux desktop architecture to prevent malicious software keyloggers? What would be an ideal Linux setup to make it very difficult for an attacker to install a keylogger ...
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28 views

Inserting XSRF header token in Hydra

I'm trying to break a login form with Hydra. The site is built with the Angular framework, and an XSRF token must be sent through the header and through the POST request. I notice that the XSRF ...
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49 views

Does KDE System Tray Extra Items “Clipboard” have the same security threats as the system clipboard?

Does the clipboard under kUbuntu's KDE System Tray > Extra Items "Clipboard" have the same security threats as the system clipboard? The following articles point out the insecure nature of the ...
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6answers
4k views

Why is it considered safe to install something as a non-root user in Linux environments?

We always hear it is safe to run unknown programs as non-root users in Linux because non-root users are sandboxed from the system level and can't change anything out of their permission scope. If ...
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37 views

What can possibly happen to a public SSH server?

I'm writing a console emulator in JQuery, which will connect to a server through SSH and dynamically send commands (through AJAX) and receive output. Basically it will be a remote ssh console on a ...
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48 views

Defense-In-Depth With Common Security Controls

Many operating systems implement system capabilities, Posix access controls (DAC/ACLs) and mandatory access controls (SELinux), each using different underlying security controls to provide individual ...
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51 views

Does an account with a !! /etc/shadow entry have to still expire?

Currently where I work, our password policy is set at 84 days. This is set in our login.defs on all of our Linux machines. We have policies that are set around PCI DSS 3.1 and the like, this goes for ...
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2answers
82 views

Tracing origin of malicious PHP script

I'm looking at a Linux server running Apache + mod_php. A malicious PHP script was uploaded during the night. It's owned by the Apache user and I would think it almost certain that the script was ...
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1answer
409 views

Turn RPi3 Wi-Fi adapter into monitor mode using airmon-ng

For some reason, I can't turn the built-in Wi-Fi adapter on the new Raspberry Pi 3 into monitor mode like I used to do on other platforms. First I kill the processes that interfere with sudo airmon-...
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2answers
88 views

Protect against virus and malware attacks from website ads with iptables

Lots of websites spread malware by publishing advertisements that distribute malware. Even YouTube's ad network has been compromised in the past. Browser ad blockers and related plugins have there own ...
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1answer
42 views

How to disable conntrack protocol parsing in the linux kernel?

Security researcher Jacob Appelbaum suggested to avoid certain code paths in the linux kernel that are related to conntrack that do protocol parsing (such as fdp, sip, etc.) right in the kernel for ...
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3answers
3k views

Does using a live CD make you more vulnerable to remote attacks?

Some people recommend the use of a Linux live CD for online banking, but doesn't that make you more vulnerable to network attacks since it's not updated? I tried installing updates and it required me ...
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1answer
84 views

What is the most valuable file you can get using a directory traversal hole [closed]

I am doing a penetration test and I found a directory traversal hole in the web application which enables me to download any readable file in the server. However, I could only download files that is ...
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1answer
257 views

My server was hacked and I am asked to pay to recover my files

Today I got a message when I logged on the server: Hi, please view: http://pastie.org/private/tlixxvclirxmut6djqyacq for further in ...
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3answers
99 views

Does a reverse proxy pass keep the backend server anonymous?

If I have an NGINX server at 1.1.1.1 and in the NGINX server you have the config that forwards on http traffic to 2.2.2.2: upstream 123 { server 2.2.2.2; } server { listen 80 default_server; ...
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64 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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1answer
78 views

Linux log files to back up and review for security

Good morning/afternoon/evening everyone, I am looking into what files I should consistently back up externally from my machine to be able to monitor for any unusual activity. I would look at the files ...
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62 views

Tuning auditd to be more operational friendly

We are in the process of pushing for a passing SOC-2 audit report, and part of that is to get our auditing act together. Specific to what I'm working on right now auditd. I have a nice set of rules, ...
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How do I execute a file under Linux Mint when it could be 'unsafe'? [duplicate]

Sometimes I find PDF's on the world wide web which I need for a project etc. But I'm afraid to get some sort of malware, virus or whatever on my PC too. I'm using Linux Mint. I would like to download ...
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110 views

X windows security: VNC and X server vs xpra

I have a CentOS server that currently has no X server on it. It will be used for doing statistical crunching and providing other services (probably via a web interface). The main security for the ...
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171 views

How to verify if a source code is safe before compiling it?

Sometimes Linux users need to to download a source code to be compiled then executed (the root privileges is granted). Is it possible for a source code to hide malicious code as a part of it? And how ...
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Port Knocking origination matching problem

I set up port knocking using first this method using knockd and then I tried using this method using only iptables directly but when both failed I thought I'd check a bit deeper into the problem. ...
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1answer
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Can going to a bad website on firefox, or installing a malcious firefox plugin, infect other parts of my home folder on a Linux system?

BTW, I don't mean root, just a plain user. I'm worried because I'm scared that if I do such things I could infect my Chromium folder. I got a huge case of OCD.