Securing Linux systems and applications; understanding Linux security features.

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4
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2answers
64 views

SSH: Security of Pubkey Authentication vs Password

Why is Pubkey Authentication considered more secure than a password, and does this apply to my situation (described in more detail below)? I'm a scientist (no formal IT training), but I built and ...
3
votes
1answer
99 views

Is a newly installed server with no services running (but connected to the web) at risk?

A new server has just been installed but literally has nothing else running on it, no services setup to SSH in or anything yet (it's a Linux server). However, it is hooked up to the web so I can ...
0
votes
1answer
78 views

Server full disk encryption protection from malware

A group of LINUX servers is using dm-crypt to encrypt data. The servers do not store data long-term but are only temporary stopping points for data before it is sent to other systems. The time the ...
2
votes
0answers
60 views

chroot ssh users [closed]

I am using CentOS 7. I need to give shell access to ssh users but restrict them in a jail. I have used jailkit to set up the jail. I have copied all necessary libraries, binaries that are needed for ...
1
vote
1answer
56 views

Linux Kernel module signing

If the linux kernel is compiled to check for kernel modules signing, it checks the validity of the public key (X.509) w.r.t the current system time. For the first time the system is booting up, it ...
4
votes
1answer
86 views

How can I delete a password and lock the account in one step?

I have a minimal server install on a remote machine with a root password set to a temporary, but chosen, value. I have added a separate administrator user. This user has an authorized key for SSH, no ...
5
votes
1answer
2k 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/ ...
4
votes
1answer
154 views

/dev/random in EC2 cloud

is /dev/random any good in AWS EC2 for use in making a shared key that will be passed over a secure channel? i am concerned that a launched instance would have not much entropy to begin with. what ...
1
vote
0answers
57 views

Linux: Chinese Unionpay plugin, Ubuntu 64-bit - Spamware / Trojan?

China / Linux / Bank / Trojan / Backdoor / Executables Hey guys. I've got an account with a Chinese bank (I live here), and in the process of setting up an online account for the Chinese version of ...
15
votes
7answers
4k 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. ...
0
votes
2answers
77 views

How hard would it be to scramble crypto keys in memory on command?

I'm looking for a way locate a set of keys in memory on command. Use case would be cold boot attack prevention: a trigger on rack open, scramble the keys in memory followed by shutdown in full disk ...
-1
votes
1answer
103 views

Can I use a VPN to disguise internet traffic at work? [closed]

I have seen this question asked before; I want to know if I can use a VPN to disguise my internet traffic so my employer can't see what websites I'm visiting while at work. However, unlike most ...
2
votes
1answer
697 views

GnuTLS ServerHello exploit (CVE-2014-3466) - how to verify?

So pretty much all of the GNUTLS world is worrying about CVE-2014-3466. I checked my Kali and it responds with this - # apt-cache rdepends libgnutls26 | grep -v lib Reverse Depends: ...
2
votes
1answer
384 views

Are there any security implications in creating an SSH key for the root user?

I've written an install script on a server to quickly set up new sites in the /srv directory. It needs to do a git clone, and has to be run via sudo in order to have the permissions to do all the ...
1
vote
2answers
120 views

Code Vulnerability in Shell script

I was given an assignment for my Computer Security class. We we were given a piece of code to analyze and determine the vulnerabilities that it might have. #!/bin/sh # shell script to create a copy ...
0
votes
1answer
116 views

Moving /tmp to an encrypted tmpfs

BLUF: I'm using an SSD on my system, so my primary reason to use tmpfs to increase the life of my drive by moving high read/write files to volatile memory. But from a security point of view, I'd also ...
2
votes
3answers
187 views

How bad is it to *not* reboot a server after kernel updates?

I’m administrating a few Debian Linux server, and install package updates when apticron notifies me of them. Occasionally I see updates to linux-image-[something] packages, but don’t bother to reboot ...
2
votes
0answers
45 views

GUI isolation in X11 when entering Truecrypt password

I have been getting a bit paranoid regarding some of my old TrueCrypt containers. The paranoia has got nothing to do with suspicions regarding TrueCrypt itself (after the shut-down last year), rather ...
0
votes
0answers
27 views

Apache.exe trojan attack on xp server, wiped it with a linux install am i safe? [duplicate]

Hello I ran a apache web server on a windows xp pc on my home network. My antivirus picked up an attack, but didn't prevent it. It seems I had a Trojan attack on my apache.exe that got through. I know ...
70
votes
9answers
14k views

Hardening Linux Server

We have already had questions on here about Hardening Apache, Hardening PHP and Securing SSH. To continue this trend I am interested in what steps people take to harden Linux servers. As in what ...
42
votes
7answers
9k 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? ...
0
votes
0answers
43 views

Is it possible to lock guest VMs (or processes) to sticks of physical RAM to prevent row hammer attacks?

I was wondering if it is possible through some means to isolate processes (or preferably guest VMs) to physical sticks of RAM. This would be to prevent row hammer like attacks from using physical ...
4
votes
1answer
90 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 ...
1
vote
1answer
198 views

Securing a VPS network with a VPN and a DMZ

I've got several VPS boxes (Digital Ocean boxes w/Ubuntu) that I would like to lock down from the outside world. I want to have several private boxes (web servers, db servers, puppet/master boxes ...
0
votes
1answer
73 views

OWASP + Atomic ModSecurity Rulesets - Too much?

Looking to implement some additional mod_sec rulesets on our server. OWASP and Atomic keep coming up as the best of the best. Would it be wise to implement both? Or, would one or the other be ...
2
votes
1answer
52 views

How to verify installed packages [closed]

On Linux (Debian x64) I recently installed some software with: apt-get install the_package_name APT told me some packages couldn't be authenticated but I ignored the warning and installed anyway. ...
28
votes
4answers
22k 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 ...
6
votes
2answers
561 views

Linux kernel entropy - does it matter to /dev/urandom and what is a minimum?

This question had been asked several times, but still something's not clearly understood from other answers I have a few servers running with a custom built linux kernel (minimal driver modules etc), ...
5
votes
2answers
377 views

IPsec on multicast

I am trying to implement IPSec for multicast communication, I tried strongSwan for setting up IPSec for unicast but it doesn't support any standard for multicast ipsec as listed here ...
0
votes
2answers
6k views

Hydra https-form-post

I have never experimented much with online password crackers. I attempted to use Hydra today on this website www.athena2.harker.org and I keep getting false positives. This is what I have done so ...
2
votes
1answer
239 views

linux hidden OS

I have been reading about hidden volume OS with truecrypt, and now with its successor, VeraCrypt. https://veracrypt.codeplex.com/wikipage?title=VeraCrypt%20Hidden%20Operating%20System But Couldn't ...
5
votes
2answers
100 views

Linux random number compliance

Not sure if this is the right forum, and I am pretty sure that his must have been answered before (I searched a lot but I haven't found a definitive answer). Do the Linux random number generators ...
2
votes
1answer
159 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 ...
2
votes
0answers
126 views

Snort alerts analysis (web interface) [closed]

I have a question about Snort (or maybe any other IDS/IPS, any working solutions would be ok). The goal is to set up some web interface providing a way to view the whole TCP stream packets of each ...
22
votes
3answers
2k views

Linux-based Turla trojan

There are several articles describing the newly discovered Linux-based Turla trojan. But basically, all these articles repeat the same, very limited, information. Can anybody provide more details, ...
-2
votes
1answer
75 views

Official proof (document) that Linux is safer and faster than Windows [closed]

I work for the Mexican government, and even though everyone involved in Linux knows that it is safer and runs faster in most instances, I have not found an official document or authority that I can ...
1
vote
2answers
146 views

Vmware over unsecure os

I run VMWare with Linux through my Windows OS. I want to use the Linux VM for online transactions. Is it possible for a virus, spy or worm to attack my Linux VM from the Windows host? Is my Linux ...
6
votes
1answer
192 views

Is it possible to emulate real network printer i.e. to run some actual firmware in VM?

I've got to the section related to network printers exploitation while going through one security course. Under "network printer" I understand standalone devices with a dedicated ethernet\wireless ...
1
vote
2answers
295 views

Setting up a security lab, looking for a little guidance [duplicate]

I'm new here. Over the past couple of years I've had a growing interest in the security aspects of IT/CS. Recently, I've started setting up a lab for myself based on a kali/win7 dualboot and I've ...
9
votes
4answers
3k views

How to detect Meterpreter and similar malware?

Is it possible to find Meterpreter or similar malware which doesn't modify the hard disk but is only stored in RAM? Most common anti-rootkit software like rkhunter and chkrootkit don't find it.
5
votes
3answers
1k views

Is GPG suitable as part of a password manager and generator?

I assume that GPG is very strong to crack, guess, etc. Since I have confidence in GPG, would it be appropriate to use my GPG key as the master key for a password manager or generator?
0
votes
1answer
52 views

Linux Updates to Shellshock

My question is about the community response to Shellshock. What improvements were made in either the Linux development cycle or in the recommendation to its users to prevent something like ...
-1
votes
2answers
70 views

Server Files Got Exposed, What Security Steps Should I Take? [duplicate]

so I made a script that would accept a GET request through a script on my page download the url in the GET and then echo the response. Sort of like an in browser proxy. Basically someone found out ...
2
votes
1answer
179 views

exploiting Heap Overflow in gdb segfaults

I have been trying to exploit the heap overflow vulnerability for the program below, I am running Linux 14.04. #include <stdio.h> #include <string.h> #include <stdlib.h> int n = 5; ...
2
votes
1answer
341 views

How does SELinux affect the Linux Kernel networking stack?

I'm interested in how SELinux effects the processing of packets through the networking stack. I've found the following questions and answers: Network policies under AppArmor/SELinux Filtering ...
0
votes
1answer
59 views

is return-to-libc attacks possible Now?

I'v read that to make a successful return to lib-c attack, the attacker should store the address of the command (for example "bin/sh") in stack exactly after the return address to 'system' function ...
-1
votes
2answers
53 views

How can I detect mode interface of other machine is promiscuous [closed]

I have a project that is to protect my box from attack man in the middle arp poison. I should detect if interface mode of other machine is promiscuous. I must write script python or command linux.
2
votes
1answer
119 views

How to find stack pointer for overflow bug?

I've read that stack usually starts in same address so the attacker may guess the starting point of the buffer to overflow. This is necessary to know this address to make the malicious code run. I ...
0
votes
0answers
15 views

I Use Precompiled Open Source Software. Is There a Backdoor? [duplicate]

I'm new to Linux world (3-4 months with Linux). But I did compile some programs from source and had one failed attempt to compile a custom Linux kernel. One thing that I'm wondering about is the ...
4
votes
1answer
101 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 ...