Securing Linux systems and applications; understanding Linux security features.

learn more… | top users | synonyms

3
votes
1answer
108 views

Hacked debian server alternative boot

The server of a customer has been hacked last night. It is a standard debian distribution with mysql, apache and ssh for remote access. The way it has been hacked is very peculiar. The standard URL ...
61
votes
8answers
14k views

Should I change the default SSH port on linux servers?

Is there any advantage in changing the SSH port, I've seen people do that, but I can't seem to find the reason why. If you have a strong password and/or a certificate, is it useful for anything? ...
10
votes
1answer
253 views

Using TPM with well-known SRK/owner passwords?

First, I will explain roughly how I plan to use the TPM: I am using something called tpm-luks which stores a key in both TPM NVRAM and adds the key to one of the LUKS keyslots. The initramfs then ...
4
votes
3answers
4k views

How Tor, Privoxy, Vidalia and Polipo are getting together?

I realized that these applications are frequently used together. What is the role of each software in the mission of anonymity and privacy on the web? While I understand Vidalia is a GUI provider, I ...
2
votes
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 ...
-5
votes
3answers
4k views

Can I do hacking using Windows OS? [closed]

I have searched the web a numerous times but haven't found an explicit answer to my question. I've studied (at school and on my own) computer networks for 2 years, doing active programming for 4 years ...
1
vote
0answers
70 views

From xss to rce in client side [closed]

I found a desktop application in Linux w/c getsvand that displays items from site xyz. xyz is vulnerable to XSS and code injected there is also executed on client side's desktop app.similar to this ...
3
votes
1answer
66 views

Blocking all incoming traffic, will it still accept a response from a request I initiated?

I am a 'newbie' when it comes to firewalls, but I am trying to launch some machines that will connect to Facebook's Graphs API. I only want these machines to contact Facebook and nothing else. By this ...
1
vote
1answer
65 views

MitM attempt resulting in ICMP redirects

I am trying to 'man in the middle' a device on my wifi network. I have configured it to use my Linux machine (also in the wifi network) as a default gateway. On the Linux (attack) host, I switched on ...
3
votes
5answers
666 views

Home Banking, antivirus safe environments OR Linux on virtual machines?

Which is the safest way to do home banking, given that I do use Windows on a tablet, I do connect to both private and public networks and I cannot use a Linux live distro right now? I've been ...
6
votes
1answer
140 views

Is there any security risk allowing regular Linux users to run arbitrary code?

I'd like to allow untrusted users to run arbitrary Node apps. If I use iptables to block everything except trusted servers, make each user's home folder only visible to them, and use runuser to start ...
1
vote
1answer
96 views

security updates for embedded firmware Tomato (router) [closed]

I installed on my Linksys router Tomato firmware. I saw and now don't understand how security updates work. It can't be that there is no vulnerability since 2010. Tomato Firmware v1.28.1816 ...
0
votes
1answer
177 views

Is BSD more secure than GNU/Linux? [closed]

BSD controls the OS while Linux is just a kernel. BSD is less popular than Linux, but which one is better in terms of security?
3
votes
1answer
90 views

IPSEC End to End Tunnel Throughput

I have established a IPSEC tunnel ( standard configuration , with ESP) , on two Linux machines (centos6 , core i7) communicating over 1 gbps LAN , and i'am checking the communication throughput. It ...
5
votes
2answers
167 views

Securely decommissioning a dedicated server

One of my dedicated hosting CentOS servers hit 12 years. I received an end-of-life notice on it, and I started receiving SMART errors as well. I guess it's time to let it go. But before I do, I'd like ...
0
votes
1answer
57 views

Test the security of my Linux setup [closed]

I have a Ubuntu installation running in VirtualBox. I have made a few modifications to it (some kernel modules and startup scripts) that I hope would make it very secure. Is there anyway I can test ...
4
votes
2answers
226 views

How do shared hosts protect different sites?

I host all my websites from a single VPN, and am about to sell some limited space of my Linode to a friend to host their new blog. It'll simply be another entry in Apache, and then a dedicated folder ...
23
votes
5answers
5k 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 ...
4
votes
1answer
61 views

Protect sensitive information in a password-free, shared database

I'm working on a webserver that stores resources in Redis. To make swarm-deployments as hassle-free as possible, I'm implementing an option where the server doesn't need to access the filesystem to ...
4
votes
1answer
143 views

Mitm attack problem [closed]

I have a problem with implementing this attack. I have a kali linux machine on vmware workstation. My router is - 192.168.1.1 My victim ip is - 192.168.1.254 arpspoof -i eth0 -t 192.168.1.1 192.168....
3
votes
0answers
67 views

Practicing with return-2-libc exploits

I am trying to reproduce a return-to-libc for a simple vulnerable program. The tutorial is taken from https://sploitfun.wordpress.com/2015/05/08/bypassing-nx-bit-using-chained-return-to-libc/ I made ...
42
votes
2answers
6k views

What is happening now with the Grub backspace key security vulnerability?

I have just read an article about a new Grub vulnerability. The article said that you can bypass the password protection by pressing backspace about twenty eight times. I am a security guy and I am ...
0
votes
1answer
1k views

mprotect at kernel level

What would happen if a kernel-level process sets some of its memory pages as PROT_NONE with mprotect and another kernel-level process tries to read one of these protected pages? What is the equivalent ...
2
votes
2answers
432 views

Limit Packets Per Second

Since last week I have been seeing something fishy and it seems to be worsening. I tried many firewalls and they seem to be useless. I blocked all unwanted ports and only few ports are open so I found ...
67
votes
6answers
38k views

Should I get an antivirus for Ubuntu?

Considering the recent thread regarding anti-virus for the Mac I wonder how many of the arguments put forth are relevant today to Linux systems, specifically Ubuntu. There are no known Ubuntu ...
5
votes
2answers
120 views

Can malicious software be installed inside Linux swap partition?

Is it possible for a virus of any kind to be installed inside Linux swap partition? If so, could it be transferred to the system even after formatting the Linux partition only and reinstalling the OS (...
3
votes
1answer
127 views

Laptops SSD: Hardware Encryption plus DM-Crypt/Luks - Security and Performance

I just bought a new Thinkpad t450s, and put a Samsung 850 pro in it. My Cpu supports AES-NI and the SSD supports hard-ware based encryption. My question is, is there any reason to do Both Hardware-...
6
votes
1answer
583 views

How to detect malicious code sending information to attacker's server in linux

Suppose you have some malicious code on your linux laptop, for example a rootkit or trojan or something like that. Now restrict your attention to the case that the malicious code does transfer some ...
-4
votes
1answer
169 views

What is the most secure mobile os? Ubuntu? [closed]

What's the most secure mobile os for the average day to day user concerned with protecting online banking, personal data, photos etc? And is the new Ubuntu mobile os likely to have the same security ...
5
votes
2answers
1k 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?
1
vote
2answers
115 views

Are there any security benefits in deleting the private key of a https webserver after starting it?

Say you have a web server offering pages via HTTPS. After the process begins running, if you were to delete the private key, would this prevent private key recovery in case of server compromise? ...
1
vote
0answers
175 views

IPtables accepting SMTP without being configured?

While setting up the IPtables rules for a new server, I set up Postfix and send an email to try it out. To my surprise the email arrived without me declaring a rule for the port in IPtables. ...
5
votes
2answers
159 views

Is it possible become root through a broken symlink owned by root and globally writeable?

I'm looking for a vulnerability on a server. I'm looking in the /var directory and I get something like this: drwxr-xr-x 3 root root 4.0K Aug 14 21:02 kerberos drwxr-xr-x 12 root root 4.0K Nov 11 ...
1
vote
1answer
144 views

Strange SECCOMP entries for sshd in audit log

I've posted this over at ServerFault but haven't received a response over there. I'm not a security professional, but I'm curious as to what kind of attack this might be and how the attackers might be ...
5
votes
1answer
111 views

How to grant permission to read a text file to a specific application run by a regular user?

A text file is situated in /opt/somefolder. It contains a pair login - password read by an application when authenticating on a server. The application is run by a regular user, so that the file can ...
0
votes
4answers
674 views

How can I use netcat like ping?

How can we use the netcat (nc) to determine whether a particular machine is running web, mail or SSH services?
3
votes
0answers
43 views

Address of environment variable different for each directory

I'm writing a return-to-libc attack for a school project. My script retrieves the system(), exit() and shell addresses as follows (it's a sh script that calls some c programs): Create the environment ...
7
votes
1answer
99 views

Impact of using a NON-SSL/TLS connection for API calls on same server

I have two domains hosted on the same server, Domain A and Domain B, both domains have different IP addresses, assuming IPs 1.1.1.1 for Domain A, and 2.2.2.2 for Domain B. Each domain has a different ...
3
votes
2answers
152 views

Is using Chrome and Tor Browser at the same time secure?

I question this recently because as I was using the Tor Browser, while in the same time my Google-Chrome was opened, and I right-clicked on a word to search it in 'Disconect', when the page loaded I ...
29
votes
4answers
3k views

Can the root user be removed from a *nix system to prevent privilege-escalation?

Once a *nix system is properly configured and hardened, is it a conceivable strategy to remove all super user/root users? Are there benefits to removing root from a system altogether to prevent super-...
1
vote
0answers
58 views

Under which circumstances is the default security profile of XRDP considered okay?

In xrdp.ini, the base install of xrdp on my raspberry pi*, there I have the following below. I changed crypt_level to high. [globals] bitmap_cache=yes bitmap_compression=yes port=3389 crypt_level=...
0
votes
1answer
61 views

How can I check whether file modified time has been spoofed on ext4?

On Debian based system (Ubuntu 14.04.3 server specifically), using ext4 filesystem. How would I discover if files have been changed, but the modified times have been made to look like the files have ...
11
votes
7answers
1k views

How are open-sourced operating systems and software kept secure?

I have been wondering about his for awhile. I have Linux running on a PC at home. I had a jailbroken iPhone. They both have attributes that make them very attractive, and they are also FREE! But I ...
5
votes
1answer
169 views

VM production server and low entropy

I'm monitoring a VM functioning as our production server. I noticed it has at many times, quite low entropy (/proc/sys/kernel/random/entropy_avail). On average our server(which among other stuff does ...
3
votes
1answer
46 views

Prevent snapshots of VPS

Pretend I have a server. Is there anyway to prevent (or make more difficult) the administrator from taking snapshots? Feel free to give me a software way, or suggest if I should change server types; ...
3
votes
2answers
200 views

Decoding injected PHP malicious code in my server

I've found on internet similar issues, and I compared the code. This one is different. I recently found out that the CentOS LAMP webserver we use for development in our office was infected by a piece ...
2
votes
1answer
117 views

Linux antivirus and files bigger then 4GB

I wish to scan files that are bigger then 4GB. For example video files. I noticed many antivirus software are limited to a maximum of 4GB (ClamAV for example). So: Is there a antivirus software ...
4
votes
1answer
47 views

Is protecting a parent folder secure enough to protect files within that folder?

So this topic came up during a hardening exercise on Unix/Linux machines where a parent folder was marked with chmod 740 but files within that folder were marked chmod 644, and the argument went that ...
-1
votes
1answer
106 views

Understanding HTTP response from Linux Server

I am working through a question that involves someone using a vulnerability in a Linux server in order to gain access to it. The first part of the question states In monitoring the network activity ...
0
votes
2answers
104 views

Is there a tool to detect what technologies a website uses? [closed]

I'm looking for the name of a tool I've used a long time ago, that for a given URL/website address would extract the technologies used for that site. For example that the site is running Apache, using ...