Questions tagged [security]

Security covers a wide-ranging set of topics including Users, Permissions, Authentication, Authorisation, Upgrades, Firewalling, Hardening, etc.

438 questions with no upvoted or accepted answers
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1answer
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List and remove unofficially installed CA certificates

This article expose how around 18% of HTTPS connections are being detected as intercepted by MITM proxies. As the great related paper state: To circumvent this validation, local software injects a ...
7
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1answer
5k views

How can I add an SSL client certificate/key globally in Ubuntu?

I have a web server which requires a client certificate to establish an SSL connection (SSLVerifyClient require in apache). In firefox or chrome, I simply import the .p12-file containing my ...
6
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1answer
297 views

Apport error reporting privacy issues

As apport is enabled by default since 12.04 I thought it would be important to get some much needed clarifications on certain privacy questions that have been bugging me. How paranoid is apport about ...
5
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1answer
406 views

How to install an isolated or sandboxed debian package?

Suppose there exists a particular debian package in the Ubuntu repositories, which upon installation pulls the actual software from an external repository such as sourceforge. The software itself ...
5
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1answer
843 views

How is the guest account prevented from using su and sudo?

It's already known that the guest account can't use su or sudo: Why is su disabled from guest sessions? Sudo not available in guest login How is this done? My guess would be apparmor. However, ...
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0answers
1k views

OpenJDK, IcedTea security settings

I am a beginner Linux user. From my knowledge the system uses OpenJDK and IcedTea only when I connect to a SAP IDES server through SAP GUI JAVA adding a string in it to connect to that server. I use ...
5
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1answer
233 views

Kernel security levels in ubuntu

Is there any ubuntu equivalent of BSD Kernel Security Level? If yes, how can one change the security level?
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0answers
1k views

Is there a guide for using GRSecurity and Precisew/ PAX?

I'd like to know if there is a guide of some kind for (successfully) configuring, compiling and installing GRSecurity w/PAX etc. in Precise? I basically am trying to build my own custom release ...
4
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1answer
46 views

How to prevent last screen from appearing after turning back on my computer

Each time I suspend my computer, after I turn it back on, the last screen state before suspension shows up in the blink of an eye - showing possibly web pages, terminals, applications etc. -, then the ...
4
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869 views

Chromium Password Manager NOT requiring password to view passwords

I'm using Ubuntu 16.04 and chrome://settings/passwords is what I'm talking about. I was going there to check a password that I forgot, and to my surprise, clicking the Show Password button shows me ...
4
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2answers
1k views
+50

How can I block traffic over wifi before the VPN connects?

I'd like to use a VPN when on public wifi for security. In order to establish my OpenVPN tunnel I need a working network connection. When I connect to a public wifi access point there is a window of ...
4
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1answer
231 views

How to secure myself from the libpng buffer overflow in png_set_PLTE security bug?

As of today, there is a security bug affecting the libpng library. The severity with this is, that the library is used by huge amount of projects: browsers, music players, games, Linux Distro's. ...
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547 views

How to disable mpm-itk for a specific virtualhost?

I've a main site on a server that needs to run a sudo command which I white listed via visudo. That worked fine until I installed apache-mpm-itk and then I started getting the following error: sudo: ...
4
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2answers
1k views

How to prevent users from deleting files that are already in use?

Consider this scenario: User is executing a command on a file. This file becomes 'in-use' now. $ tail -f somefile.log In another shell, user deletes the file. $ rm somefile.log Now, this file is '...
4
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1answer
1k views

Web server atacks

I have a server (vps) to use as a repository and testing (gitlab and redmine) server. However apache crashed, seeing the /var/log/apache2/error.log have many errors of this type: [Fri Jan 31 16:07:...
4
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1answer
715 views

Any CA Cert trusted by default on ubuntu?

I understand I can copy the CA cert to certain location and run script update-ca-certificate to import CA cert to the system. But I'm curious is there a list of CAs that are trusted by default on ...
3
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0answers
42 views

What are the meaning of the abbreviations DNE, needs,needs-triage and so on?

https://people.canonical.com/~ubuntu-security/cve/main.html ubuntu What are the meaning of the abbreviations DNE, needs,needs-triage and so on?
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886 views

How to sandbox Chromium that's installed via SNAP?

In Ubuntu 19.04, you can install Chromium using snap like this: sudo snap install chromium However, when installing Chromium via snap, you cannot sandbox it with firejail like this: firejail ...
3
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2answers
755 views

Simplest and most scalable way to isolate ImageMagick in VM or container

For users of my web service running on Ubuntu Server 16.04 or 18.04, I’d like to integrate features from such useful programs as ImageMagick. For example, I’d like to crop their profile pictures or ...
3
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0answers
2k views

Allow a regular user to mount VeraCrypt volume without admin privileges

A regular user is unable to mount a VeraCrypt volume without first authenticating with an administrator password. According to the original TrueCrypt documentation, the workaround is to give the user ...
3
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1answer
133 views

Can VeraCrypt be made available for users securely on a server?

I have VeraCrypt installed on a server and want to think about making it available to users on the server to make encrypted files in their home directories. What are the security vulnerabilities to ...
3
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0answers
639 views

2 factor authentication using a USB drive

I want to set up 2 factor authentication using a usb stick/drive. I'm using Ubuntu 16.04 and it seems that libpam and pamusb no longer work for this version. I don't want to use google authenticator, ...
3
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2answers
397 views

Unknown binary file named “0” in /usr/local/src/

I was cleaning my server today and found a file in directory /usr/local/src/ File Attributes: Name: 0 Size: 975MBs Type: Binary (I tried to cat the file) Location: /usr/local/src/ Permissions: -rw-...
3
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1answer
712 views

DNS leaking on Ubuntu 16

I use a VPN. When I check DNS leak testing sites, my original ISP is shown. My government in the UK logs and spies on every internet connection legally and I don't want this to happen because although ...
3
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1answer
158 views

Ubuntu-make (umake) security: package signatures?

ubuntu-make (umake) can be used to install the latest version of a variety of popular developer tools. How secure is this process and how does it compare to the security built in to apt-get, such as ...
3
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2answers
96 views

Encrypt a file and destroy all unencrypted copies

I have a text file with various passwords, usernames and financial information on it. Suppose I want to encrypt it, then rsync copies to various devices. If I use GPG to encrypt the file, how can I ...
3
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0answers
84 views

Folder Access Log?

Most of the work I do is in a computer running ubuntu that I access via SSH, which is administered by a colleague of mine. Some of the data I have in a folder is somewhat sensitive and I would like to ...
3
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1answer
134 views

What are the possible reasons a kernel security update would fail to occur during unattended-upgrades?

I have setup unattended-upgrades along the lines of the Ubuntu AutomaticSecurityUpdates doc. However, it had not updated to the latest Linux kernel, which was definitely a "security" update. What are ...
3
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0answers
557 views

Is my Ubuntu Desktop under attack?

I am currently facing random freeze of my Ubuntu(16.04) desktop and screen fills up with the garbage pixels. I even cannot start command line using Ctrl-Shift-F1. Every time I have to manually do the ...
3
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0answers
468 views

After editing root .bashrc Unable to login even with tty1-6 and drop to prompt command from recovery mod

I have had the worse two weeks started with Ubuntu 12.04 , and updating to 14.04 had problem , just after a good luck of successfully installing brand new ubuntu 14.04 I now got the nightmare again ...
3
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0answers
945 views

Does Ubuntu store passwords from failed login attempts?

This is probably a stupid question, but if I type in an incorrect password while attempting to log into my account, does that password get stored anywhere? Assuming that I don't have any third-party ...
3
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2answers
2k views

Encrypt second hard disk with same password

I installed Ubuntu 14 LTS with disk encryption (selected during installation). I have two questions: 1- What is encryption algorithm of current encrypted disk? 2- I have a second hard disk and I ...
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0answers
715 views

Problem using 'ecryptfs-unwrap-passphrase'

I have 2 laptops running Ubuntu 14.04. 1> The Toshiba supplies the mount passphrase when I run 'ecryptfs-unwrap-passphrase' 2> When I run 'ecryptfs-unwrap-passphrase' the HP does not supply ...
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0answers
872 views

How can I use a Verbatim Secure'n'Go USB key?

I have purchased a 4Gb USB key from Verbatim. How can I use it under Ubuntu? I do not need the "secure data" feature, and have still not saved anything on it, so formatting at low level would be OK. ...
3
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0answers
91 views

How to auto restart services when you get security updates?

That's related to the heartbleed bug. While my server (12.04 LTS) was configured to perform unattended install of all security updates, it seems that nginx was not restarted so it was still affected ...
3
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2answers
2k views

How to configure a SSH server to use a certain public key?

I have a dual boot Windows 7 / Ubuntu 12.04 desktop and I have installed openSSH server in both (using cygwin64 under windows). I connected from my laptop, running Ubuntu 12.04, to the Cygwin64 ...
3
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0answers
685 views

Apache shows blank white page after 2 to 10 hours

I am using ubuntu 12.04, it has to network cards, A = internal 10.0.0.0 and B public Ip , I have only apache2 installed, after 2 to 10 hours the website shows as a blank white page on the public ...
3
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1answer
1k views

Setting Up Users and Permissions for a Multi-purpose Home Server

I have decided to repurpose an old grey box computer to be a combination NAS/home media server, headless torrent server, and minecraft server. I am using this both as a practical piece of equipment ...
3
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2answers
62 views

is there some sort of all-purpose logging tool I can download as a package?

As in, a tool that will give me easy to read logging information all in one convenient place, divvied up into categories. Logs for say, ssh daemon, user logins/logouts and other activity, installed ...
3
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1answer
128 views

Setting up a intrusion system

I am trying to set up a intrusion system for 12.04 LTS and was pointed in the direction of using PAM to do so. How can I setup PAM and is there any other intrusion system out there for ubuntu?
3
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1answer
344 views

How can I monitor/control applications making network connections?

I found out about nethogs and iftop the other day, and ran them. I was surprised to see some applications running daemons I didn't know about. It's fine now that I know about them, but I'd like to be ...
3
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0answers
930 views

How can I check the checksum of an installed deb package against the same package in the repository?

Suppose someone got root access to my machine and replaced some files, e.g. Warning: The command '/bin/which' has been replaced by a script: /bin/which: POSIX shell script text executable Warning: ...
3
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0answers
1k views

Why does network manager automatically choose WEP over WPA & WPA2?

I am on Ubuntu 12.10 and for some reason my wireless connection is using WEP when it is set to use WPA/WPA2 Personal. Also I should mention that I used to be on 12.04 and was experiencing the ...
3
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1answer
927 views

How can I block a range of IPv6 addresses?

Are there any IP blocking applications or firewalls that support IPv6? The ones I know about (pgld, moblock (sunset?) , nfblock, iplist (looks old)) are only for IPv4.
3
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1answer
210 views

Is file permission secured when it transferred from Ubuntu to Windows?

I am having 9GB text file which is encrypted . This file contains some confidential data . Which is on my system(Ubuntu) and my external HDD (ntfs) . This file get daily updated and then encrypted . ...
2
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0answers
69 views

Linux security(?) issue Ctrl+Alt+F7/F8

Ubuntu Desktop 18.04 LTS amd64. User A logs into Ubuntu. Then he switches to user B. Now user B can access user A's GUI by pressing Ctrl+Alt+F7. User A can also access user B's GUI by pressing Ctrl+...
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0answers
44 views

block flow with iptables

To block packets containing some string we use the following iptables rule: iptables -I FORWARD 1 -p tcp --dport 80 -m string --string anypattern --algo bm -j DROP This will block the packet ...
2
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0answers
74 views

Unknown Device in power notifications

I'm new to Ubuntu. I kept seeing power notifications and assumed they were for the battery. But then I found that they actually were for another device: ELAN2514:00 04F3:262C. That device is unknown ...
2
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0answers
163 views

Why should all world-writable directories be owned by a privileged group?

I'm reading an Ubuntu security guide developed for the US Department of Defense, to be found here. Written for 16.04 but I don't think this particular item has changed much. The guide says, Group ID (...
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0answers
241 views

SCAP Workbench: Scan of 18.04 shows status “notapplicable”

I recently learned about OpenSCAP. Today I wanted to take a closer look, so in installed scap-workbench and tried to scan the machine with the provided Ubuntu profiles. I tried VMs with Ubuntu 18.04, ...

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