Securing Linux systems and applications; understanding Linux security features.

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128 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 ...
2
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1answer
347 views

Dump linux password in clear text

Is it possible to dump a Linux password in clear text format? In Windows it is possible to do so using "Windows Credential Editor".
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1answer
73 views

RDRAND in Intel Celeron CPUs under Linux

Is there any reason to believe that the hardware RNG in an Intel Celeron CPU is more unreliable than in other CPUs? Can someone confirm that what Linus Torvalds says is true, namely that Linux does ...
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0answers
107 views

How 'private' is my setup?

I'm currently running QubesOS (so essentially a virtualized Fedora operating system), which I use to access an offshore VPS through I2P (using garliccat). I then route all my traffic through the VPS ...
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2answers
188 views

How to overwrite ebp on stack alignment?

I want to exploit a simple program #include <stdio.h> #include <string.h> int main(int argc, char** argv) { char buf[128]; strcpy(buf, argv[1]); return 0; } The disassembly ...
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0answers
23 views

At OpenSSH ssh server side key files has 0 data. I would like to know the reason for it

I am using the Monta Vista Linux. In this recently i have observed the ssh keys files has 0 data due to which the keys were not generating and i am not able to login to machine via ssh because of key ...
4
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1answer
159 views

Desktop Flickers Past Lock Screen

I'm using Fedora 22 with Gnome 3. I have a password set for my user account, so when my laptop awakens from sleep, I am presented with the lock screen and must enter my password before getting to my ...
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2answers
301 views

Does the new Fedora package manager allow unauthorized installations?

I just upgraded to Fedora 22. The biggest change from the previous version is that the yum package manager is now replaced with dnf. One change I've noticed is that if you try to execute a command ...
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2answers
70 views

Are there any dangers in sharing ifconfig information publicly?

If I were to share my ifconfig information from Linux publicly, is there any possible danger associated with this action?
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1answer
812 views

How to use wordlist [closed]

I have downloaded a wordlist from https://crackstation.net/buy-crackstation-wordlist-password-cracking-dictionary.htm The size of the wordlist is 4.2 GiB (compressed) or 15 GiB (uncompressed) The ...
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5answers
1k views

How secure is it to keep the salt with the password hash? [duplicate]

In Linux we have the salt just next to the password hash in the /etc/shadows file. I always hear that salt value prevents hashed passwords from being cracked by brute force methods. But if somehow we ...
5
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1answer
146 views

Video site requests Adblocker to be shut off, next day I have 3 “weird” bookmarks

I was on a site trying to view a video and the site requested that I turn off my adblocker to view the video. So I did and then the next day I noticed that I had 3 "weird" bookmarks in my bookmark ...
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2answers
413 views

How to make data in hard disk unrecoverable on linux [duplicate]

I need to wipe completely the data on my hard disk so it's unrecoverable. I'm actually using Linux, i have seen this command on the web, but I don't know if its secure. shred -zvn 35 /dev/sdb
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1answer
99 views

When can the exploit for CVE: 2006-7098 be used?

I'm studying the vulnerabilities of an old version of Apache, the 1.3.34. And I don't quite understand in what exact situation the CVE 2006-7098 vulnerability can be exploited. The README included in ...
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2answers
181 views

Can BTRFS provide authentication on an encrypted disk?

One of the problems of disk encryption is providing authentication. An attacker with access to the ciphertext can modify the ciphertext at will without consequence. Given, this isn't a likely attack, ...
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0answers
325 views

TPM Command Line Tools

I am trying to create a key storage hierarchy on TPM (Trusted Platform Module) on Linux (CentOS 6.4). The most commonly recommended TPM tool suite on Linux is TrouSerS. However, the command line suite ...
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2answers
176 views

PCI-DSS, what is the best distro? [closed]

What is the best distro of Linux to get PCI-DSS compliant? I am using Debian 8 because I think Debian is one of the most stable versions, but it seems not to be enough, I am struggling with a lot of ...
8
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1answer
1k views

Why is plain dm-crypt only recommended for experts?

I am curious about the following claim from the Cryptsetup FAQ: 2.4 What is the difference between "plain" and LUKS format? First, unless you happen to understand the cryptographic background ...
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2answers
557 views

Can I VPN a phone's connection to my home network, and then apply my home firewall to my phones network connections?

I have a decent firewall/router at home, and I was wondering whether it would be possible to use my home firewall for the connections that my phone makes, even when I'm not at home. It would mean ...
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2answers
87 views

How to use Aircrack-ng when knowing part of the password?

Let's say I know the password starts with "1234" and after that there is a commonly used password. I would like to use the word list I have for the second part of the password, but to include somehow ...
2
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2answers
50 views

Which software RNG for linux?

A headless server can suffer from a lack of entropy, which is a problem given that encryption needs random numbers. In the absence of a hardware random number generator (RNG) the numbers must be ...
5
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2answers
90 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
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1answer
118 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 ...
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2answers
170 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
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0answers
121 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
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1answer
58 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
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1answer
158 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 ...
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0answers
115 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 ...
4
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1answer
489 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 ...
38
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9answers
6k views

Is full disk encryption on a server in a secure data center pointless?

I am having a debate with several people regarding how much protection full disk encryption provides. dm-crypt is being used to encrypt data which is required by my company to be encrypted at rest. ...
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2answers
135 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 ...
0
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1answer
391 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
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1answer
522 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 ...
4
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1answer
429 views

What does a signed Linux kernel image get me?

On Ubuntu and possibly Debian systems, you can install packages which contain images which are signed by Ubuntu's EFI key. For example, linux-signed-image-generic-lts-trusty is one of these packages. ...
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3answers
677 views

Error message in Apache logs shows /bin/bash and wget

I am wondering if my server is compromised or not I just looked at my log and seen the following line in there [Thu May 14 09:10:42.587255 2015] [autoindex:error] [pid 3422] [client ...
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2answers
304 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
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1answer
360 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
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2answers
95 views

Vulnerability test for CVE-2014-2483?

I am in penetration testing on a server with Linux RHEL6/7 os. Vulnerability databases such as http://www.cvedetails.com/ mentioned the vulnerability CVE-2014-2483 for Java in Linux RHEL systems. I ...
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2answers
174 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 ...
3
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1answer
298 views

How to check whether my USB flash drive was infected by the BadUSB

After failing to check whether my USB stick firmware can be rewritten AT ALL, I want find out, whether it WAS rewritten when I sticked it in another computer. In particular the question is: how to ...
12
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1answer
3k views

How to check if my USB stick firmware can be rewritten via the USB port?

How can I know in Linux (or otherwise), if the firmware of my USB flash drive can be rewritten using the USB port (when sticking it in an USB port)? Eg. for a cheap EMTEC 16GB. I was thinking about ...
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3answers
393 views

Linux Plausibly Deniable File System

Is there any way to encrypt a linux filesystem in such a way to maintain plausible deniability? E.g. "Hidden OS support," the way Truecrypt and Veracrypt work, they only support Windows OS due to low ...
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52 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 ...
5
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1answer
164 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 ...
0
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1answer
114 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
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1answer
99 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. ...
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2answers
808 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), ...
2
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2answers
2k 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 ...
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2answers
158 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 ...
5
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2answers
697 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 ...