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Questions tagged [ubuntu]

Ubuntu is a Linux version derived from Debian. For questions about Ubuntu that are not about security, please post on [AskUbuntu.SE].

2
votes
1answer
21 views

Do openssl CA certificates get updated with apt-get upgrade?

I use Ubunut 18.04. I need to know if OpenSSL CA certificates that are in this file: /etc/ssl/certs/ca-certificates.crt get updated when I upgrade my system using: apt-get upgrade? I have a ...
0
votes
2answers
93 views

Boot from live usb to avoid being spied on

Suppose the government wants to spy on you using government-designed malware. If you then want to visit sensitive pages on the internet, would it be more secure to use Tor browser within a USB - live ...
0
votes
0answers
16 views

Kalil linux Gnome 3 freezes [closed]

I have installed Kali linux light version. When I update to full version , After login the screen freezes. Installed kali in laptop, with intel graphics and nvidia geforce 1050.
0
votes
0answers
4 views

CA certificates location in Ubuntu 18.04 [migrated]

Can you please point to me where can I locate the CA certificates file in Ubuntu 18.04? I have a program that needs the path that point to the CAs directory for certs. validation.
2
votes
2answers
39 views

How do i know if my ubuntu apache version is secure?

I am running Ubuntu 16.04 LTS and checking dpkg -l apache2 gives me version 2.4.18-2ubuntu3.9. How do i know that 2ubuntu3.9 has the latest security patches listed here at https://httpd.apache.org/...
0
votes
0answers
39 views

Debian repository security: Is switching mirrors dangerous?

I have been recently alerted about https://blog.packagecloud.io/eng/2018/02/21/attacks-against-secure-apt-repositories/ . The site claims that "Acquire::AllowInsecureRepositories" is enabled by ...
-1
votes
1answer
59 views

How to switch from Ubuntu 18.04 to kali linux? [closed]

I am using now ubuntu 18.04.1 and i wanna make dual boot with kali linux. How to do that?
44
votes
4answers
12k views

Should I close port 80 forever and ever since the 2018 Google-indicated web-security initiatives?

I often establish Ubuntu-LAMP environments on which I host a few Drupal web applications that I myself own (I don't provide any hosting services and never done so in the past). Whenever I establish ...
2
votes
1answer
42 views

Containerization vs. Chroot in shared hosting

Forgive my rudimentary understanding of server security, but one thing I've always struggled with was understanding how to setup chroot to separate folders (which are discrete WP installations) in a /...
6
votes
2answers
2k views

Why can 'Others' read files by default in Ubuntu?

I am trying to figure out why when creating new files and directories in, let's say, the Documents folder, they get assigned, by default, the following permissions: -rw-rw-r-- 1 hello world 0 Nov ...
-1
votes
0answers
12 views

OpenVPN can't establish connection on Ubuntu 18.4 [migrated]

My OpenVPN credentials work on Windows 10 but I am having difficulty connecting from Ubuntu 18.4. It is simply reporting that the connection failed on Ubuntu. The config files, cert and key are all ...
-1
votes
2answers
78 views

How can i access any useful information in a wordpress site?

While penetration testing for a university assignment, I found an exploit that might be the one the teacher has been hinting for, found here: https://www.exploit-db.com/exploits/45439/ I used it and ...
0
votes
1answer
59 views

Read-only to the root user

Is there a permanent and secure (as in integrity) way to make the entire Ubuntu system of a VPS (virtual private server) read-only to all users (including the root user)?
2
votes
1answer
33 views

Limit rights for user applications

I have a website, where users are available to upload small applications which runs 24/7 on my server. So if the user upload an application, some folders will be created: /{USER_ID}/{APP_ID}/ (if ...
3
votes
1answer
101 views

How to enforce on the OS level to recognise only certain keyboards

I give employees AES wireless keyboards. I would like to enforce the OS to only recognise the keyboard we supply. Is that possible? Assuming my employees OS are Windows 10, Ubuntu, Mac OSX. How could ...
5
votes
5answers
169 views

Unix Privilege Escalation: “sudo must be owned by uid 0 and have the setuid bit set”

It seems protections are harcoded into sudo that prevent the binary from executing as a low-privileged user. Running it in Ubuntu as a normal user returns the following error: "sudo must be owned ...
1
vote
1answer
45 views

OpenVPN one account multiple servers & Load Balancing

I have recently been experimenting with OpenVPN. My aim is to create a group of servers in different locations with a single username and password for each user stored in a central database. For ...
1
vote
1answer
97 views

Files on external drives executable by default with exFAT or NTFS under Ubuntu

On Ubuntu, if you use (external) drives formatted as exFAT or NTFS, i.e. not ext4 or something made for the UNIX world, you may end up with a situation where all files are executable. This is because ...
2
votes
1answer
45 views

Securely Download lubuntu from Non-Ubuntu System

The recommended way to find out which public key you need to verify the Ubuntu hashes is to attempt to check a signature of the hash file (both of which were downloaded in the clear). This produces an ...
1
vote
2answers
45 views

Add main user account to docker group

I recently installed ubuntu on my home system. As I am going to mainly use it for machine learning research, I tried to set up a python environment. I tried doing this with docker to make things ...
0
votes
1answer
82 views

Unexplained DNS connections on boot

I was on an Ubuntu VPS today, with a bind9 DNS server (without DNSSEC configured) installed and running. Immediately after booting the machine I ran: netstat -tanp And received this output: Proto ...
0
votes
0answers
114 views

Uninstall metasploit completely on Ubuntu

So I want to remove completely Metasploit because there was a problem that I couldn't describe. And I want to reinstall it after that. I couldn't find the uninstall script so I deleted 2 folders ...
0
votes
1answer
87 views

Is my Vino server being attacked?

I installed vino on LUbuntu 18.04, and configured and started my vino server according to https://askubuntu.com/a/530196/1471 without understanding what the commands mean: $ export DISPLAY=:0 $ ...
3
votes
0answers
129 views

Weird attack making my server CPU super high

I noticed that my server CPU is super high and the reason is grep "A" command After a deep look, that what I've found in my active internet connections list (netstat -tupn) tcp 0 0 ...
1
vote
0answers
138 views

Buffer overflow experiment: shell code executed but got “failed to read 0 bytes” error

I've doing a buffer overflow experiment on a Ubuntu 16.04 VM (Linux ubuntu 4.10.0-28-generic #32~16.04.2-Ubuntu SMP Thu Jul 20 10:19:48 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux) and got a puzzling ...
3
votes
2answers
326 views

What is this SSH attack, am I hacked?

I see this in my Ubuntu server's log file: in my ssh my user is root but i see other user Disconnected like "teamspeak", what does that mean? auth.log Jul 3 21:39:01 vmi189193 CRON[25937]: ...
1
vote
3answers
178 views

When hardening a LINUX system what command line tools would you remove first in order to make an attackers life really difficult? [closed]

When hardening a LINUX system what command line tools would you remove first in order to make an attackers life really difficult?
2
votes
1answer
60 views

Is there a security tracker aggregated file for Ubuntu server like Debian has?

Debian has a JSON file containing all CVE<->Fixed package versions map. Link: https://security-tracker.debian.org/tracker/data/json Does Ubuntu have something similar?
16
votes
1answer
489 views

Password shown on screen after crash on Linux, any idea why?

So, my computer crashed during the night and when I came to work in the morning I had the following screen on. I did not type the password a single time after the crash. It appears to be related to ...
1
vote
0answers
279 views

2ip.io/privacy/ and 'Defining tunnel (two way ping)' on SOCKS5 proxy

I was able to setup my first proxy server on Ubuntu 14 using danted. However, when I visit 2ip.io/privacy/ and run their privacy test, they return: Defining tunnel (two way ping) found This is ...
55
votes
3answers
16k views

Why has Ubuntu 18.04 moved back to insecure Xorg?

After reading Xorg becomes the default display server again and considering the security risk of xorg, I am wondering why the developers left Wayland. The fact that a few programs do not work on ...
1
vote
0answers
49 views

SUID not executing as root [duplicate]

I am trying to learn about SUIDs and have run into bit of a stumbling block - I have a ubuntu 16.04 system. I have set a few default binaries such as vim, find et al. to have SUID permissions as ...
-1
votes
2answers
95 views

Why have distributions default HTTP package sources instead of HTTPS [duplicate]

Many distributions have HTTP links in their sources list for packages. Proof: https://docs.parrotsec.org/doku.php/mirrors-list https://docs.kali.org/general-use/kali-linux-sources-list-repositories ...
2
votes
2answers
264 views

VPN doesn't function properly on google websites

Why do google sites display content in my original country's language even if i'm connected to the internet through a VPN? For exapmple: google.com and youtube displays content in my actual language, ...
0
votes
1answer
50 views

Disable guest access in / directory Ubuntu [duplicate]

Follow up from: https://stackoverflow.com/questions/49703000/how-to-see-into-guest-account-filesystem-from-root I am root, and I need to restrict write or read access to / directory for a certain ...
1
vote
1answer
31 views

How to verify Ruby on Rails projects are at current patch levels?

I've got a few Ruby on Rails systems running Ubuntu 14.04LTS. The Ubuntu version of supported Ruby is 1.9.1 but the developers use a Gemfile and Bundler which (AFAIK) installs Ruby (and gems) out-of-...
1
vote
2answers
199 views

Malware techiques via Linux Chrome and its effects, non-root

Is it possible to visit a website with Chrome on Ubuntu and have that site execute shell code on my machine without explicitly downloading anything nor click on some Chrome execute question/popup? If ...
3
votes
2answers
332 views

odd ip address connected to my box

Today i went to the library. I was looking at my netstat -an output and i saw this. tcp 0 0 127.0.0.1:6379 127.0.0.1:46376 ESTABLISHED tcp 0 0 127.0.0.1:46376 ...
-5
votes
1answer
355 views

How does resolv.conf work? [closed]

Can someone try explaining (in simple terms) how Wi-Fi routers push nameservers and routes to my resolv.conf? I've noticed it gets changed automatically as I move between different Wi-Fi networks. I ...
0
votes
0answers
147 views

Why does Ubuntu deem 16.04 un-affected by CVE-2017-16995(Kernel Privilege Escalation) while it's not?

In both current OVAL definition and CVE Tracker, it says for Ubuntu 16.04 While related to the CVE in some way, the 'linux' package in xenial is not affected. But I have tested many kernel ...
24
votes
3answers
8k views

Is this what a brute force SSH attack looks like?

I reviewed the auth.log file on my Ubuntu server to find: [preauth] Feb 22 17:39:18 code-storage sshd[17271]: Disconnected from 147.135.192.203 port 49408 [preauth] Feb 22 17:40:15 code-storage sshd[...
0
votes
0answers
127 views

Auditd not writing to log after clearing without a service restart

I noticed that if everything is working fine with auditd on Ubuntu, and then the log at /var/log/audit/audit.log is cleared (all the text erased, the file is not deleted), auditd will no longer log ...
2
votes
1answer
266 views

SSL - Enabling Forward Secrecy with or without RC4

I'm running an Apache 2 server with Ubuntu 16. Here's my current configuration: SSLProtocol All -SSLv2 -SSLv3 SSLHonorCipherOrder on SSLCipherSuite I'm a bit confused as to what I should use for ...
2
votes
1answer
110 views

Appearance of yam bitcoin miner

I had a VM based on Ubuntu 16.04.03 and the only package added to it was OpenVPN. The purpose of it was to provide a VPN into my private network sited within the cloud environment. The hypervisor ...
1
vote
1answer
204 views

Can malware have its own GRUB/boot-loader and use it to be active?

I use Ubuntu 16.04. After I mounted an ISO which may or may not have had malware in it, my system sometimes ends up showing a blank screen after logging into Ubuntu or reboots a minute or two after I ...
0
votes
0answers
76 views

Shellcode on different Operating Systems?

Due I was testing some code, to learn. I tried to use a sample code in Assembly 32 bit, which I compiled. And exported it to an environment variable. Then I got the hex-address of the shell code ...
1
vote
0answers
69 views

Is there a way to make the login screen in ubuntu need ctrl-alt-del to put in your info? [closed]

In Windows, there is an option for a logon screen that looks like this: Image is there a way to do the same thing on Ubuntu?
2
votes
2answers
333 views

SSHguard: Does one to change any configuration for basic usage of the program?

I use Ubuntu 16.04 and I've installed SSHGuard (sudo apt-get install sshguard -y) to protect from Brute Force Attacks (BFAs) on whatever user. From reading about the program in ArchLinux wikipedia ...
2
votes
1answer
36 views

webapp directories should have the directory name as owner and group?

Some programmer told me that my usual way to change ownership and permissions to my webapp dirs isn't good: sudo chown www-data:www-data /var/www/html/* -R He told me that this could result in a ...
3
votes
1answer
164 views

How to set basic defense on Nginx-CMS?

As an Information Security amateur I did all in my might to protect my Ubuntu-Nginx-CMS (WordPress) environment from BFAs, MITMs, and database injections. sudo add-apt-repository ppa:certbot/certbot -...