Content related to computer security., i.e. content about policies, mechanisms, etc. needed make sure data is not leaked or corrupted and services available in all circumstances.

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18
votes
3answers
5k views

Why does the 'bin' user need a login shell?

During an audit of /var/log/auth.log on one of my public webservers, I found this: Jan 10 03:38:11 Bucksnort sshd[3571]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 ...
1
vote
0answers
45 views

Files associated with Thunderbird - Security mechanism for local storage

I am trying to know how Thunderbird stores the mails, associated files in the local machine. I use Ubuntu 13.10 and Thunderbird 24.6.0. When I see in the local profile folder in the location in ...
-1
votes
1answer
115 views

How can I update BASH [duplicate]

How can I update BASH? I noticed that there are version 4.2.45 env x='() { :;}; echo vulnerable' bash -c "echo this is a test" this is a test cat /etc/redhat-release CentOS release 5.11 (Final) rpm ...
1
vote
1answer
132 views

Shellshock - not vulnerable with bash version 4.1?

We have several Amazon servers. It has bash version 4.1.2. Kaspersky claims that all bash versions up to 4.3 are unsafe. When I do this test... env x='() { :;}; echo vulnerable' bash -c 'echo hello' ...
18
votes
11answers
4k views

How to create strong passwords in Linux?

I wonder how I can create strong passwords on Linux (for both normal and admin users) and if there are specific programs to do that.
1
vote
3answers
91 views

Securely passing user input to command

I have a daemon daemon running in Server A. There, there's an argument based script to control the daemon daemon_adm.py (Server A). Through this script I can insert "messages" to daemon coming from ...
0
votes
2answers
54 views

ClamAV found virus, if I should delete this virus? [closed]

ClamAV has found two viruses on my server. Is this a virus? Should I delete it? /tmp/back: Perl.Shellbot-8 FOUND /var/tmp/back: Perl.Shellbot-8 FOUND
2
votes
2answers
42 views

What is best and secure way to save application settings?

Let's say I have an application which has plugins, daemons, etc. Now It has to save its settings and plugins settings as well as too. Most of all applications use users home folder for it but it is ...
0
votes
0answers
45 views

Cannot label F2FS (SELinux)

I'm running Arch Linux [testing] x86_64 For some reasons, I can't relabel my root file system (F2FS) with SELinux (custom kernel compiled, using refpolicy) Kernel ver $ uname -a ...
6
votes
3answers
633 views

Is w command safe for users?

Some applications allow to pass password as an argument. For example: mysql --user=user_name --password=your_password db_name Is it safe? Besides the fact that typed password would be saved in bash ...
8
votes
2answers
7k views

How to apply the fix for CVE-2014-6271 bash vulnerability on cygwin?

I would like to find out how do I apply the fix for this vulnerability on cygwin. I am running the CYGWIN_NT-6.1 MYHOSTNAME 1.7.30(0.272/5/3) 2014-05-23 10:36 x86_64 Cygwin of cygwin on Windows 7. ...
1
vote
1answer
3k views

Which Debian patches fixes shellshock lcamtuf CVE-2014-6277 and CVE-2014-6278? [closed]

Note that this question is definitely not a duplicate of: When was the shellshock (CVE-2014-6271/7169) bug introduced, and what is the patch that fully fixes it? According to: ...
7
votes
4answers
19k views

How to only install security updates on debian

Because of the Shell Shock bug I need to make updates on some of our machines. But I am not sure if all of the packages suggested in apt-get upgrade are OK for my system. In other words I am not sure ...
0
votes
0answers
68 views

SC_ERR_NOT_SUPPORTED(225) with Suricata on CentOS 6.5

I have just installed installed Suricata 2.0.3 RELEASE on CentOS 6.5. I try running it with sudo suricata -c /etc/suricata/suricata.yaml -i eth0 and get the following warning <Warning> - ...
8
votes
2answers
160 views

Why is the ability to definine functions in an enviromental variable not a security risk in itself?

As I understand it, generally it is considered safe to let anyone provide information that will be stored in an environmental variable. The shellshock vulnerability is an issue here because it means ...
3
votes
1answer
28 views

How can I lock down a user account to the point that it can read/write/execute as little as possible?

I would like to lock down an Arch Linux user account to the maximum extent possible. The only functionality required for the account is to accept a non-terminal SSH session which allows the client to ...
0
votes
0answers
18 views

DEBUG_RODATA option in the linux kernel

I am wondering what exactely the use of DEBUG_RODATA is in the linux kernel. The help says: CONFIG_DEBUG_RODATA: Mark the kernel read-only data as write-protected in the pagetables, in order to ...
4
votes
1answer
24 views

Yum security model OR Why can a hostile proxy deny updates without a warning?

A friend of mine just had the strangest kind of problem where his Fedora 20 would not update to (or even find) the current kernel 3.16.3 (and incidentally also not update the vulnerable bash version). ...
1
vote
0answers
22 views

Are there any loopholes in IP restricting sshd?

Say that i want to only allow username/password logins on my private network, but restrict all external sources on to key/cert login. I would do something like this: RSAAuthentication yes ...
1
vote
2answers
194 views

How does the latest “Bash Bug” or exploit affect systems that require authentication?

I'm curious to know how the latest Bash Bug affects systems that require a user login to access the shell. Isn't UNIX/Linux usually configured in a way that you have to be an authenticated user to ...
2
votes
0answers
29 views

Are there risks to auto-login/passwordless login other than physical access control?

Does auto-login/passwordless login leave the computer in exactly that same state as it would be after manually logging in, or does it create security risks of a type other than physical access ...
0
votes
0answers
49 views

Permission denied tmp dir on STIG RHEL

I am writing a program for a DISA STIG version of Red Hat Linux 6.5. I wrote a shell script to do self extracting on the program and when it self extracts put temporary files in the tmp directory that ...
7
votes
1answer
5k views

What is the severity of the new bash exploit (shellshock)? [duplicate]

Alternate title: Should I be worried? I've been reading up about the remote bash exploit and was wondering how severe it is and if I should be worried, especially since a new exploit has been found ...
4
votes
3answers
4k views

CVE-2014-6271 Bash Vulnerability example [duplicate]

I am trying to understand what could be the security concern of CVE-2014-6271 and all the links I see just gives me the below command. env x='() { :;}; echo vulnerable' bash -c "echo this is a test" ...
0
votes
1answer
42 views

What are the potential negatives of turning on process accounting (psacct package)?

I am looking into turning on process accounting on some EL6 servers. What are the potential pitfalls of turning this on? If you mitigate storage requirements with log rotation, any reason you would ...
5
votes
1answer
3k views

Linux: LUKS and multiple hard drives

I have a Debian Linux system (amd64) installed on a RAID-1 system encrypted device (LVM on LUKS) and will have a RAID-6 of >=4 disks where I'll put my data (LUKS and maybe LVM). I think the basic ...
0
votes
2answers
56 views

Accessing Linux server via VPN or Certificate based ssh?

My company has a fairly common security setup where you need to log in via VPN, when outside the company network in order to get access to the servers. The biome is mostly Windows machines. I'm ...
1
vote
1answer
63 views

Is the data transiting through a pipe confidential?

I read the following question (Shell Script mktemp, what's the best method to create temporary named pipe?) but I'm wondering whether it is preferable to use a temporary named pipe to transfer ...
0
votes
0answers
32 views

Security of Fedora third party repo RPMFusion

Due to the nature of Fedora licensing, it does not come with many propeitary software like adobe, flash, and codecs. So many Fedora users resort to using RPMFusion. My question is how safe is ...
0
votes
3answers
170 views

How to add a password to a specific command

I've been searching google on how to add additional security to a specific command without using sudo. Is it possible to add on a security feature without actually using sudo? For example: Whenever ...
3
votes
1answer
53 views

read only symlink or something similar? [duplicate]

I created myself a NAT for home use (Ubuntu+Samba+Greyhole+Apache+MySQL+other web server related stuff). 90% of files I store there are pictures that i really don't wanna loose (that's why Greyhole). ...
1
vote
0answers
41 views

Change password hashing to PBKDF2 on Debian-based OS

I'm looking for a way to change the hashing scheme on my Debian-based OS from sha512 to pbkdf2. Searching the internet hasn't helped much. The closest I've got is this question: Enable Blowfish-based ...
3
votes
1answer
66 views

How do I remedy SELinux not allowing legit programs in use access to my system?

I have a system where some programs are getting access denied in SELinux when performing their duties. These programs are ClamAV, fail2ban and Logwatch. I think I've managed to allow all the access ...
8
votes
2answers
9k views

How can I block a range of IP addresses with an Amazon EC2 instance?

I know a certain range of IP addresses are causing problem with my server, 172.64.*.* what is the best way to block access to my Amazon EC2 instance? Is there a way to do this using security groups or ...
1
vote
2answers
66 views

How Does Whonix Keep The User Anonymous?

How does Whonix Linux keep a user secure? I am aware of how it works in terms of the Gateway which uses Tor, but how does the Whonix workstation ensure nothing is logged, or stored, on the OS and no ...
1
vote
1answer
25 views

What are these %(…)s strings in fail2ban's jail.conf file, and how do they work?

In setting up fail2ban there are what appear to be variables at the top of the jail.conf that look like this: mytime=300 . . . [ssh] bantime=%(mytime)s Or in this more complicated form like this: ...
1
vote
0answers
12 views

Is there a Linux capabilities(7) to allow a process to execute pam_authenticate?

I am writing a process that needs to periodically authenticate users (i.e. call pam_authenticate()). For security purposes I would prefer not to run this process with root privilege. I can use ...
2
votes
1answer
229 views

Do I have thousands of attempts to breach my system in this log from logwatch?

I'm setting my systems up to send me reports by email. I'm posting one log report (see below). This log shows that there are thousands of attempted break-ins. Questions: I have denyhosts and ...
2
votes
1answer
42 views

How to extract a list of user accounts deleted from the system over a period of 1 year? [closed]

I'm auditing an AIX and a Linux system and I would like to know how many user accounts were created and deleted over a 1 year period. Is there some way of getting this data from the Unix system?
34
votes
4answers
4k views

Why is root login via SSH so bad that everyone advises to disable it?

Everybody on the Internet advises to disable root login via SSH as it is a bad practice and a security hole in the system, but nobody explains why it is so. What is so dangerous in enabling root ...
0
votes
1answer
34 views

Not to ask for grub password

I set a superuser and password for grub in Ubuntu and whenever I turn my machine on it asks for username and password... I want when I hit e on my keyboard just asks me for username and password... ...
9
votes
1answer
217 views

Why does the location of Enviroment Variables vary that much?

Reading the book Hacking: The Art of Exploitation by Jon Erickson, I am trying to approximate the address of an environment variable SHELLCODE to exploit a program. Every time I run ...
1
vote
1answer
66 views

apache mod_security and performance

I have a list of bots to block, so I was thinking that fail2ban could be a solution until I realized that mod_security would be more efficient in this kind of tasks. The number of bots is huge, so ...
0
votes
1answer
246 views

I stopped MiniSSDPD, will something bad happen?

I have been trying to harden my Debian system by stopping and disabling the 20 or so unnecessary services listening by default. One of them is called "minissdpd". Apparently this provides "discovery" ...
0
votes
1answer
34 views

how many password generators are there in debian and how to know which are good

I know of two password generators in Debian. The first one which I have used is apg and it seems to generate some good passwords. $ apg -m 15 -M SNCL RefGav:quedTut7 {Shtetmigdybig1 ...
9
votes
2answers
3k views

How to ensure SSH port is only open to a specific IP address?

This is my /etc/sysconfig/iptables: It has two ports open 80 apache and 22 for ssh. # Firewall configuration written by system-config-firewall # Manual customization of this file is not recommended. ...
0
votes
0answers
39 views

ubuntu linux - security between applications

When I run a Ubuntu Linux on my machine, and if using only 1 user account, most of the applications executed are using the same uid. I want to know what risks do applications face in this ...
-1
votes
1answer
49 views

How to use partial IP address in /etc/sysconfig/iptables for the “-s” flag?

in this example it is a full ip ip is: 1.1.1.1 -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -s 1.1.1.1 -j ACCEPT but suppose i want to allow any ip that simply starts with: 1.1. ...
2
votes
0answers
32 views

How to use a separated user with GUI on OpenBSD?

A webbrowser is a GREAT attack vector since people use it to access the "dangerous" internet. Very bad things can come in through to the desktop. So in general for a desktop, we can do the ...
2
votes
1answer
30 views

How to verify one file of a package, not the RPM itself

For instance, can I somehow use rpm to verify that /etc/pam.d/system-auth is unchanged since it was installed on the system? I know I can do this with an entire RPM, but I want to know if I can do ...