Securing Linux systems and applications; understanding Linux security features.
5
votes
3answers
496 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
2answers
477 views
Difference between vulnerabilities on windows/linux/mac for same program
If someone finds a vulnerability like buffer overflow in a program such as Google Chrome or Mozilla Firefox running on a linux machine, are there any chances that this vulnerability will persist on ...
3
votes
2answers
2k 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.
...
5
votes
2answers
810 views
Breaking out of a strict linux sandbox running virtually under windows: do the linux-sandbox access control policies even matter?
I am developing an application which will run untrusted code. I have been designing it for linux, thinking that I can just run it in a virtual machine on windows when the need arises. The linux ...
10
votes
8answers
4k views
How anonymous is my setup?
my friend and I are trying to make the most anonymous setup for a computer to do things across the internet without being known the location from which it came.
Our setup is as follows:
A windows ...
6
votes
1answer
793 views
Securing restricted shell environments
I've read a few things to indicate that restricted shells can be broken out of if not implemented properly (even wikipedia, for instance).
I'm looking for some guidance on what causes security holes ...
8
votes
2answers
1k views
Which Linux kernel vulnerabilities allow installing a kernel-level rootkit?
My question is related to vulnerabilities that allow installing a Linux kernel-level rootkit (for example, to modify the execution flow inside the kernel; for return-oriented attacks; or to modify ...
6
votes
2answers
4k views
Sudo password when authenticating via passwordless SSH
I've got a few boxes all networked together on Amazon EC2, each of which are in automated communication with each other via SSH (rsync, etc). As such, I've created SSH keys on each of these machines ...
3
votes
7answers
1k views
Server compromised for 2nd time, cannot locate source of attack
I need some help tracing a vulnerability on my server. For the second time, my server has been compromised with files being replaced with virus-ridden downloads.
According to the filesystem dates, ...
2
votes
3answers
991 views
Privilege Escalation Ubuntu
I am trying to learn how an attacker can escalate privileges in Ubuntu 10.04. I have heard that this can be done but no one has ever said how to do it. The best defense is knowing how it is done and ...
6
votes
1answer
1k views
loop-aes or dm-crypt for linux hard encryption?
loop-aes and dm-crypt are both used by partman-crypto for linux hard encryption, but dm-crypt needs no patch to kernel and is more supported.
dm-crypt keeps it's key on first hard block, is it a ...
0
votes
0answers
431 views
Ubuntu home folder encryption, compared with file vault [closed]
I want to know if there are any limitations that are imposed on you when you enable home folder encryption in ubuntu.
Example, in the mac file vault, at least on Snow Leopard, time machine, and ...
0
votes
1answer
492 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?
3
votes
2answers
140 views
How do shared hosts protect different sites?
I host all my websites from a single Linode VPN, and am about to sell some limited space of my Linode to a friend to host their new blog (it's going to be a simple wordpress blog).
It'll simply be ...
3
votes
1answer
797 views
ARP-poisoning on wireless network - no packets
I've started working with ettercap and ARP-poisoning; however, I've sumbled upon some problems. I've executed the following command:
ettercap -i wlan0 -w log -T -M arp:remote /192.168.1.254/ ...
11
votes
5answers
678 views
Convenient cross-platform help on checking secure hashes like SHA-256
It is often helpful to be able to obtain a good cryptographic checksum of a file, e.g. the SHA-256 hash. This can be used to verify file integrity, so long as you have a reliable source for the hash.
...
5
votes
4answers
3k views
Monitoring system calls (in a reliable and secure way)
It there a reliable method of “monitoring” system calls under Linux?
There is strace for example to monitor system calls and signals. Is there a way for a process to dodge out of strace? If yes, is ...
4
votes
3answers
593 views
Wrapping system call (in reliable and secure way)
It there reliable method of "wrapping" system calls under Linux ?
(Like LD_PRELOAD for wrapping shared library function calls.)
Is there reliable, secure method of "wrapping" system calls (and, maybe ...
12
votes
6answers
791 views
Securely building a local pentest lab in a VM
I'd like to set up OWASP WebGoat or a similar vulnerable web app in a VM (probably VirtualBox on Linux). For convenience's sake, I'd like to get it running on one of the primary machines I use (say, a ...
5
votes
3answers
736 views
Fastest way to “lockdown” CentOS and have network intrusion detection, firewall, etc up and running?
Are there any proven concepts or "installers" to get up and running based on the best practices securing and locking down a CentOS installation?
Something that would scan the CentOS give suggestions ...
4
votes
2answers
1k views
Preventing Attacks Scanning for PHPMyAdmin etc
I have a Linux web server running Rails and each time I check the Nginx logs I find attempts to access PHPMyAdmin, database and admin directories such as this:
190.196.161.110 - - ...
1
vote
1answer
270 views
Should Windows 2008 R2 be used as an externally facing DNS name server?
When compared to more traditional DNS name servers, what are the benefits / drawbacks of using a Windows 2008 R2 as a public ns record for a company.
What limitations, or security issues would I ...
22
votes
6answers
2k views
Keeping secrets from root on Linux
I am looking for ways to harden a linux system so that even when gaining full root access (through legit or non-legit means), some secrets remain inaccessible. But first a little background.
Many of ...
2
votes
0answers
324 views
Adding an alternative password change scheme to passwd using PAM modules [closed]
I am trying to set up a PAM module that lets one add a conditional password change scheme. The intended behavior is like this:
passwd
do you want to change authentication token for ...
18
votes
4answers
3k views
How do you know your server has been compromised?
I recently helped a client who had their server hacked. The hackers added some PHP code into the header of the homepage redirecting the user to a porn website — but only if they came from Google. This ...
8
votes
4answers
337 views
Best practices for physically securing a notebook
If the user knows that other people will repeatedly have physical access to her notebook - running Linux - while she is absent, and that there is no way around this, what are best practices for ...
4
votes
2answers
352 views
Protecting data on a laptop with linux
I'd like to keep some private data (photos, notes, ...) and my browsing data hidden. The rest is not so important. Most of the time I just put the laptop to sleep and don't shut it down often, making ...
13
votes
1answer
507 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 ...
3
votes
2answers
957 views
/dev/random security holes
I'm doing some reading into the security issues surrounding /dev/random but it's proving to be hard to find good sources of information. Can anybody help? I've asked Google and got a bunch of articles ...
2
votes
1answer
282 views
NFS and encrypted File systems
Can a NFS mounted file system be used for encrypted /home, and can the encrypted Home Directories be mounted/decrypted for the user when they login?
7
votes
2answers
311 views
Running proprietary software on Linux safely
As a summer project, I'm looking to prevent any piece of proprietary software like many games I run from have access to my personal files. After looking a lot at sandboxing, I've decided that anything ...
15
votes
5answers
1k views
How can I protect my computer from my potentially malicious colleagues?
So, I work in this small company (10 people) where we do stuff in programming, for various platforms. I started recently working there (2 months) right after I graduated. My work is not exactly ...
11
votes
2answers
323 views
Network policies under AppArmor/SELinux
I am attempting to sandbox some untrusted processes using Linux's MAC frameworks -- either SELinux or AppArmor.
I see that both SELinux and AppArmor allow the selected granting of socket level access ...
7
votes
5answers
1k views
Browsing on a USB OS (Linux) safe from malware?
Let's say I have a computer. It's a personal computer - the one you'd typically find in homes. In this scenario, it's running Windows XP SP3, although it could run 7, Vista, etc.
I have a USB drive ...
10
votes
3answers
829 views
Recommendations for Changing the Default Shell For Service Accounts
It seems as if most Linux systems use either /sbin/nologin or /bin/false as the default shell for service accounts. Many hardening guides, such as CIS benchmarks, recommend changing the default shell ...
5
votes
3answers
345 views
Increase security without using “dynamic” kernel modules?
I recently read that NOT using loadable kernel modules could increase security. In my interpretation this consist about recomplying the kernel with only built-in kernel modules. (how to disable ...
1
vote
3answers
243 views
Is there a security problem accessing my laptop via WIFI?
I'm developing a web application for mobile devices on my local server in my laptop. My laptop is connected to company network via LAN. And, my project manager, wants to check the web application ...
5
votes
3answers
320 views
What are the security considerations for setting up a basic security testing environment?
I only have 2 spare machines and both are very old, but I really want to set up an environment so that I can start practicing security. One of these machines has a Pentium 4 processor and 512 MB RAM; ...
5
votes
3answers
397 views
Appropriate defense for 404s in my logs - persistent web scans from one region
This seems to be a fairly easy question to figure out, but I wanted to make sure. I've got about a thousand entries on one of my web servers with phpmyadmin in the connection criterion, but as I ...
3
votes
2answers
176 views
Which access rights should be chosen for doku wiki?
I'm currently making my first experiences with a CMS called "DokuWiki" (Link). This CMS needs only PHP and writes the information to files (seems to be /dokuwiki/data/pages).
At the moment I gave the ...
7
votes
2answers
1k views
For LUKS: The most preferable and safest cipher?
I'm about to encrypt two of my hard drives using LUKS, since I can't really do it myself I use the guide on the Arch Linux wiki (which can be found here). In an example in the guide the cipher ...
12
votes
2answers
667 views
Can Windows malware harm a Linux computer when it's executed with Wine?
I am an (Ubuntu) Linux user. Sometimes, I have to use Wine for running Windows executables.
I would like to know if Windows malware (virus, trojan, worm,...), i.e. malware that was not intended to ...
4
votes
3answers
378 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 ...
7
votes
2answers
338 views
Is a rand from glibc's rand secure for a login key?
Same question as Is a rand from /dev/urandom secure for a login key, but with glibc's rand function instead of /dev/urandom. And what would be a sufficiently secure seed generator?
7
votes
2answers
1k views
Securing my web-server / website [closed]
Does anyone know of a comprehensive security guide about important basics / fundamentals which should be done to secure a web-server / website? A web link would do.
3
votes
1answer
344 views
Two questions about learning Linux exploit development fundamentals
getting ready to delve into the technical world of vulnerability assessment, and I have two questions about where to find certain information.
First, I plan on reading "Understanding the Linux ...
-5
votes
3answers
543 views
Why are people saying that X-windows is not secure?
Why are people saying that X is not secure?
With X I mean: https://secure.wikimedia.org/wikipedia/en/wiki/X_Window_System
p.s.: The OpenBSD team succeeded with priviledge separation in 2003, WHY ...
16
votes
2answers
8k views
Simple example auditd configuration?
Auditd was recommended in an answer to Linux command logging?
The default install on Ubuntu seems to barely log anything. There are several examples that come with it (capp.rules, nispom.rules, ...
10
votes
5answers
3k views
Linux command logging?
Recently someone broke into one of our linux servers as a non root user.
An excerpt from .bash_history:
[...]
perl
perl
set +o history
set +o history
set +o history
passwd
sdfsdf
passwd
exit
I ...
4
votes
4answers
9k views
Tips for a secure iptables config to defend from attacks. (client side!)
Own examples:
###############
# KERNEL PARAMETER CONFIGURATION
# PREVENT YOU SYSTEM FROM ANSWERING ICMP ECHO REQUESTS
echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all
# DROP ICMP ECHO-REQUEST ...
