Securing Linux systems and applications; understanding Linux security features.

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3
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3answers
1k views

Disable Perl for some/most Linux users?

One of my server's web accounts got hacked a couple of times. Each time someone downloaded a Perl script via some phpBB forum and used the Perl script to do whatever they wanted to do (mostly connect ...
1
vote
1answer
80 views

How many connections can TCP_WRAPPERS handle?

As we know that TCP_WRAPPERS is a good way of security on linux/unix system, to disallow or allow remote user to connect to the specific services. Assume that if there have a large number of ...
1
vote
1answer
300 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
4answers
9k views

Netcat IP Spoofing

I am connecting to a server nc -v 192.168.0.1 1111 But I want to do IP spoofing because the server on 192.168.0.1 only accepting commands from 7.7.7.7. We are two friends, I am 192.168.1.1, and my ...
0
votes
4answers
719 views

What voip client support manual encryption?

In pidgin there is a plugin that we can use to encrypt our messages in chat windows .. Is there anything simular for voip (pc to pc) ? any client that support manual encryption for voice data?(linux)
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votes
2answers
139 views

how to protect a personal computer? [closed]

I am Linux user with no knowledge on security , up to now i dont know that is my system was in attack or not . I havent felt anything wrong with my system . but every Computer user must have some ...
5
votes
1answer
90 views

Testing a chroot environment for privilege escalation vulnerabilities

I'm looking for holes in my current implementation of a chroot jail that I have implemented for a group of users. Is there anything I can do better here? I utilized the following packages: RHEL6 ...
3
votes
2answers
200 views

How likely is an infection with an outdated skype on linux? [closed]

Today I found an article about a skype hotfix and noticed that the repo I use on my linux notebook: deb http://download.skype.com/linux/repos/debian/ stable non-free Doesn't have the new version, ...
4
votes
3answers
215 views

What would the cryptographic impact be of knowing the output of /dev/urandom?

Another noob question, I know, but something I'm unsure about. If I somehow magically knew the output of /dev/urandom at any given time, how much would that weaken a given encryption system? Or, ...
6
votes
7answers
4k views

Physical computer security, how to disable USB ports when the computer is 'locked'?

Lets say my PC & server is in an environment where a theoretical attacker has physical access to the machine while I'm not there. Now the data is encrypted on the hard drive with TrueCrypt. ...
10
votes
2answers
2k views

Security Concerns with X11 Forwarding

What are some of the security concerns and reasons either for or against allowing X11 Forwarding. I have generally taken an approach of not allowing it under the blanket guise of security. Recently, ...
1
vote
3answers
403 views

Danger of Path Traversal Attacks

I have setup a test application in Linux. I havent checked for paths in it, so if user enter /etc/passwd , then that file gets displayed to him. However, I want to understand what more can be done if ...
4
votes
1answer
3k 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 ...
15
votes
3answers
560 views

If I have two identical linux virtual machine images, will they generate identical random numbers?

A really noob question, I know, but something I was wondering about this morning. If this were the case, would they encrypt things identically? Or maybe someone could direct me to a helpful research ...
7
votes
4answers
3k views

What do I need to configure, to make sure my software uses /dev/urandom?

When setting up a server, what configuration changes do I need to make sure that all of the software uses /dev/urandom instead of /dev/random? Some servers don't have much entropy in the entropy pool ...
2
votes
3answers
2k views

Writing a sample virus (not harmful)

I don't know if such a question is allowed on this site, sorry if it's not For educational purposes I am asked to write a small virus running on Linux, which should just be able to inject itself into ...
0
votes
1answer
384 views

Sending Commands using Hping3

I want to send my command to destination server. I am using hping3. And; hping3 -p 9999(running daemon and commands executing on this server) -S 127.0.0.1 I want to send my command. How to?
9
votes
2answers
1k views

environment variable accessibility in Linux

Perhaps this is a trivial question, but how accessible are environment variables in Linux between different users? e.g. if Alice executes export FAVORITE_FOOD=`cat /home/alice/fav_food.txt` Can ...
2
votes
3answers
810 views

discover virus or spyware under Linux

I suspect to be the target of very skilled hackers. 5 or 6 years ago I found spyware on my Linux webserver, it was lkm masked as ppp_deflate module with md5 hash hijacked. I mean with the same md5 ...
0
votes
1answer
235 views

Looking for virus under Linux [closed]

if I am looking for a virus/spyware under linux, where should I have to look for to find it ? I suspect to be the target of very skilled hackers. 5 or 6 years ago I found a spyware on my linux box, ...
2
votes
2answers
1k views

NSA RHEL5 Checklist

The NSA has came up with the "Guide to the Secure Conguration of Red Hat Enterprise Linux 5" (http://www.nsa.gov/ia/_files/os/redhat/NSA_RHEL_5_GUIDE_v4.2.pdf) I have read through this guide and it is ...
2
votes
2answers
525 views

Allow apache to write to users' .ssh dir's

I know the title is just baiting the "your setup is insecure", but allow me to explain. I'm working on an application which aims to allow clients to rsync over SSH to our server. We need a web ...
-2
votes
3answers
3k views

Which tool (apart from nmap) can I use to scan a range of IPv6 addresses? [closed]

When I try to use nmap: # nmap -sP -6 FE80::1-234 [...] Failed to resolve given IPv6 hostname/IP: FE80::1-234. Note that you can't use '/mask' or '[1-4,7,100-]' style ranges for IPv6.[...] What ...
1
vote
4answers
3k views

How To - Learn basic hacking skills? [closed]

I'm interested in learning some basic hacking; and I've read online that Linux is a good place to start. Although, I've been a Windows user for as long as I can remember. So I was hoping I could get a ...
2
votes
1answer
111 views

Network abnormally slow during night hours

My network recently the last week as become abnormally slow around 11 pm. Very slow buffering youtube videos during all hours. Ive recently purchased the new router about two months ago but not ...
2
votes
2answers
1k views

What are the best IT auditing guidelines for Red Hat Linux 5.x+, including the critical data protection?

Currently, I am a junior application consultant and we are maintaining huge amounts of redhat machines as servers. I am given the chance and liberty by my boss (unbelieveable!) to go do my own ...
1
vote
0answers
242 views

Any suggestion for a good readerless smart card (security token) solution? [closed]

I'm developing a small CRM application that will have to store some sensitive data and I would like to (optionally) supply my users with the possibility to use a readerless smart card (aka "security ...
2
votes
2answers
243 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 ...
6
votes
6answers
7k views

Good file encryption tools

Could you please help me find a good file encryption tool? The target OS is Linux, but tools for Windows are welcome, too. FOSS tools are preferred. The tool must be reliable both for the recovery of ...
4
votes
2answers
264 views

Securing data on laptop's hdd

I was wondering which is the best way to secure/encrypt data in the hard disk on a laptop that runs Ubuntu Oneiric? Setting LVM encryption? I am mostly concerned about having my laptop lost or what ...
2
votes
2answers
575 views

up2date tools for security audit linux / centos

I'm setting up a new CentOS 6 server and am looking into some security audit tools to validate my configuration and to point out weak spots in the server. There are a lot of non up2date tools out ...
1
vote
0answers
247 views

Unauthorised Perl Scripts [closed]

One of my servers just had the memory exhausted by a load of Perl scripts, we use plesk and they seem to have appeared under the /var/www/vhosts/domainexample.com/cgi-bin/ directory, I managed to stop ...
7
votes
3answers
470 views

How to gain a shell?

I'm doing an exercise (exploit-exercises.com) that requires me to gain access to a shell running as another user. My question is this: I can create application that is guaranteed to be run by the ...
7
votes
2answers
299 views

In Linux, when I consider trusting a new software source, what do I need to evaluate?

When I'm using the Linux software PackageKit, I get confused about what specific items of information I will need in order to decide whether to authorize software installation from a new software ...
3
votes
5answers
1k views

Secure mount options + partitioning on Ubuntu

What is the best solution for mount options/partitioning when having e.g.: an Ubuntu minimal install (11.04) for Desktop use? e.g.: put /tmp on different partition to give it mount options like: ...
3
votes
2answers
805 views

Securing a Ubuntu system on Amazon Web Services

I'm in the process of setting up a Ubuntu server on Amazon Web Services / EC2, which will need to host the following: A relatively simple Java-based website (using the Noir framework) A Java-based ...
8
votes
4answers
3k views

How to disable Firewire in OpenBSD/Linux to prevent attacks through Firewire?

Since Firewire lacks security, allowing a plugged-in device to access host memory, it's a good thing to fully disable it. If we're not using the BIOS to disable the Firewire port then how could we do ...
11
votes
3answers
3k views

Installing Development Tools on Production Server? Security Risk?

I am using an Amazon Linux EC2 instance as a web server. My web app uses ImageMagick. Because the Amazon Linux (CentOS) repository doesn't include an up-to-date version of ImageMagick, I am compiling ...
13
votes
1answer
706 views

Are there Linux rootkits circulating that directly modify the kernel (without modules)?

It has been said, over and over, that disabling dynamic kernel module loading on Linux increases security. I understand why people give this advice, but I've always assumed that a bad guy could ...
13
votes
3answers
1k views

VPS security best practice

I've just signed up for a linux VPS to host a website I've been creating and I need some advice on the best approach to secure it. I've previously been hosting it off a VM in the house, but I want to ...
10
votes
1answer
1k views

Effects of DDoS attacks on memory use under Linux

Can someone whose Linux system is under DDoS attacks give me exact data on the effects of the Low Orbit Ion Cannon (LOIC), the High Orbit Ion Cannon (HOIC), Slowloris, PyLoris, Hping etc. on memory ...
3
votes
2answers
348 views

Security for home server, wiki

I recently set up my own home server, running Ubuntu linux. The intent I'm having for this is to have a private wiki for my family, so we can have a place to collect information like phone numbers, ...
1
vote
2answers
1k views

How do I figure out how malware infected my server, and the subsequent sites on the server?

I recently was in charge of fixing our server at work, and cleaning the sites on it. We were infected with some malware that injected some code into some of our clients websites. Apparently, there was ...
3
votes
0answers
104 views

Apparmor policies w/ subprocess failing [closed]

Can anyone possibly explain why Apparmor is not picking up profiles for sub-processes of a process? Right now we use God to launch an unstoppable Ruby process (in this case it's /usr/local/bin/remote) ...
3
votes
1answer
694 views

Why ESTABLISHED,RELATED for INPUT only?

In many places and tutorials I see people add this line to their iptables: -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT And they do it only and only for "INPUT". What about OUTPUT and ...
4
votes
3answers
439 views

How do I protect myself against the attacks in this php script?

Due to a vulnerability in how PHP was installed (Shared VPS with PHP installed as an Apache module instead of CGI) and hence how OSCommerce was configured (with security of 777 on certain ...
1
vote
1answer
1k views

How can log poisoning be successful with a Local File Inclusion attack?

I just read a paper about Local File Inclusion on exploit-db.com, it can be found here. One technique with LFI is log poisoning as you may know already. You do an HTTP GET request that contains PHP ...
5
votes
3answers
757 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 ...
4
votes
3answers
1k views

How to use VNC with SSH tunnel - “is this howto secure”?

PC-A: the local machine, from where i want to see the remote machine [Fedora] PC-B: the remote machine, where the vnc server will be [Ubuntu] install a vnc client [from where you want to connect] on ...
5
votes
2answers
4k views

How to secure a dedicated linux server running a LAMP stack for commercial E-commerce use

To be more specific, I would like to get some help, either through a tutorial or through a book, on how to configure an apache server to run securely and minimize the risks for commercial use. ...