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].

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What good practices do you use to secure KVM servers Host OS from Guest OS?

My questions: What good practices do you use for security on KVM servers? How do you protect Host OS from Guest OS (networking, cpu, memory)? How do you isolate Guest OS so that other Guest OSs are ...
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2answers
101 views

How do I activate a malware inside a virtual machine?

I have been doing research on malware detection and my current setup is: one host OS (Ubuntu 18.04) and one guest OS (Ubuntu 18.04) inside VirtualBox. I have downloaded and executed some malware (...
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1answer
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LAN Only Webserver

I am on a 192.x.x.x network and have a local server that hosts some webapps for the local users of the network. The server is running: Ubuntu VPN Nginx Reverse Proxy with the site.conf including: ...
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Could my Windows 7 VM access my network and perhaps my host internet history or data?

I have a Windows 7 Pro VM running on an Ubuntu 20.04 host. I'm a bit new to VirtualBox and set up the VM but it was too slow to do anything so I took a snapshot and closed it. I think my Ubuntu host ...
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1answer
80 views

How to make sure my laptop (Ubuntu 20.04) is secure with a Windows 7 VM?

I have an old laptop which is running Ubuntu 20.04 and I am planning to use a virtual machine of Windows 7 Pro (using VirtualBox maybe). As its an old laptop and not my primary source of using the ...
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97 views

Decompile a binary virus/worm

We got hacked, someone got access on our VPS machine. There are no ssh logs, there are no auth logs. There is no actual trace of remote access (that I could find and I'm not a security expert but I'm ...
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68 views

Lynis Audit Difference Between Found Known Binary and Just Found

When I run a Lynis audit of my Xubuntu system, under System Tools, binary scan, most of the binaries are returned as Found known binary: package (pkg category) - /path/to/binary But under /usr/bin ...
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100 views

How to do a post-mortem after being hacked [closed]

I am wondering what the general steps are in retrospect for trying to find out how one ends up being hacked. A couple of times I have had Linux servers that ended up being hacked. I noticed this in ...
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176 views

Cipher, for a rookie, what's safe and not safe 2021?

I'm a rookie in the cipher world, and I'm setting up squid as an TLS proxy. in an example it uses: cipher=EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:...
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1answer
143 views

How to check TCP sequence number to detect mitm?

I suspect that my router (I'm using an iPhone as router) has been owned and the attacker is making some kind of mitm attack. I suspect also that some html and js code has not been sent to my laptop ...
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1answer
165 views

Is VLC from the Ubuntu LTS official repository insecure?

Often it is impossible at first sight to understand if a package in a repository is up-to-date with security fixes, because the maintainers use a different naming when applying the patches to old ...
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299 views

Are Ubuntu Snaps more secure than the classic installation method from the official repos?

Today Ubuntu (and some other distros) offer a new way to install software, which is snaps. It's software packaged with all its dependencies, run with some kind of containerization, and auto-updated. ...
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Is this profile for AppArmor insecure?

I'm using PHP-FPM with Apache2 on my server, as PHP-FPM doesn't run as Apache2 module, I figured it would need a profile for it. This is my first time working with AppArmor, so I'm afraid of crashing ...
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1answer
300 views

How should GNU/Linux noobs harden their dekstop OS?

I'm interested in using GNU/Linux for different reasons. Partly for freedom, privacy, and security. But also to force myself to learn Linux. One issue I’ve found is that desktop Linux seems to have ...
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72 views

Should I change the default folder for uploads?

PHP 7 uses the default system folder (/tmp) to store uploaded files. PHP allows you to change the settings and change the upload destination directory. Some sites indicate to change this folder to ...
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1answer
95 views

Is there an effective way to disable root access on linux in an office setting

I'm currently working for SaaS a company and as part of a security audit we were advised to remove all administrative access from all laptops/end-user pc's for a Principle of Least Permissions. Is ...
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4answers
185 views

Mouse moving while unattended, how can I check for intrusions

A few hours ago, I spotted my unattended mouse moving and seeming to click on tabs. I promptly rebooted my system and removed Teamviewer (it's the only remote connection app that I have installed), ...
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3answers
3k views

Concerning GET request in logs

I have a Django application running on a Digital Ocean Ubuntu server. I am using NGINX and Daphne to serve the application because I am using Django Channels. My websockets keep crashing, and I ...
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3answers
7k views

How is it possible for boss to know I am finding a job?

Today, when my boss talking with me, he suddenly said: No you don't need to worry about it, everyday you have 3 or 4 messages with agent in Linkedin right? I am very very surprised, because : I work ...
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101 views

Spawning child processes from root using runuser command

I am working as an intern for an online coding platform startup (similar to LeetCode or HackerRank). The backend is written in Nodejs. Instead of running the code in a sandbox of some sort, the lead ...
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73 views

Does snapd enforce cryptographic authentication and integrity validation by default for all packages? (debian, ubuntu)

Does the snapd package manager in Debian-based systems require successful cryptographic authentication and integrity validation for all packages? I know that software downloaded with apt-get packages ...
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1answer
129 views

Does apt-get enforce cryptographic authentication and integrity validation by default for all packages? (debian, ubuntu)

Does the built-in apt package manager in Debian-based systems require successful cryptographic authentication and integrity validation for all packages? My understanding was that software downloaded ...
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117 views

ARP Spoof dropping ALL connections involved

Please note I have clicked nearly every possible link describing this issue online, and none of them have explained nor assisted in fixing the phenomena. I have a three-computer system, in which one ...
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1answer
395 views

- Exploit aborted due to failure: not-found: Can't find base64 decode on target

So. I am having some issues at metasploit. I am trying to exploit exploit/multi/http/wp_crop_rce. I am using Docker, in order to install wordpress version: 4.8.9. PHP 7.2.12 (cli) (built: Nov 28 2018 ...
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1answer
111 views

Possible to inject in the middle of a ROOT NOPASSWD command with a wild card?

I'm testing for privilege escalations on a Ubuntu 18.04 host, and after running sudo -l , I've discovered a couple of root NOPASSWD commands for a standard user (w/unknown password). These commands ...
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3answers
488 views

is there a way to close 22 ssh port from public, ubuntu?

I am using putty and private key to access my development server. I used Nmap online port scanner, to see which ports are visible to the public, and in fact, the 22 is open. My question is, is it ...
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98 views

Security implications of automatic signing of kernel modules on Debian/Ubuntu (like VirtualBox does)

In the past, to install VirtualBox on Debian/Ubuntu you needed to sign some kernel modules, otherwise it would not work. The process involved creating a key pair, importing the public key as a MOK (...
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90 views

Intercept HTTP requests for invalid domains in Linux

I am using Ubuntu 18.04. When making a HTTP request to invalid domains, I get a HTML page with javascript code that redirects me to uniregistry a landing page. More specifically, when trying to load ...
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2answers
267 views

Was there ever any malware found in Debian/Ubuntu packages?

With over 30,000 projects packaged by Debian, it doesn't seem too unlikely that some of them may contain malware. On Ubuntu's side, the review process is apparently rather superficial, aimed at ...
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440 views

Maximum password length for user accounts on Ubuntu

I have a VPS hosted at a remote location. Obviously the host can login directly (without SSH or any keys) on this box and I want to make brute force password guessing as hard as possible for a bad ...
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2answers
241 views

I found an unknown UFW rule on my ubuntu server - have I been compromised?

The server is running the Kubuntu Desktop variant of Ubuntu (I transformed it into a server, I had things configured that would have been a pain to transfer to another installation.). One day I ...
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1answer
186 views

Trojan detected in windows 10 can it affect dual boot Ubuntu

My windows defender detected this trojan: win32/credentialaccess!rfn and I tried to remove it. I use dual boot with Ubuntu: can this also effect ubuntu? If i reset my windows completely can it come ...
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1answer
154 views

Step by step protocol for complete system wipe (suspecting persistent backdoor)

I have reason to believe that there is a persistent backdoor on my device, one which is not removed after a re installation of the OS. I wanted to know the step by step protocol of system wipe to ...
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1answer
138 views

Check TRIM space on SSD

Is it possible to 'view' the space that TRIM would take care of to see if that space was really wiped? I am using both Windows and Linux.
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1answer
2k views

Investigating HP sure start triggering security warnings

The following question belongs more to the HP forums but unfortunately I am not gaining any traction there. Please move the question to another SE if its off topic for this community. Recently I've ...
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1answer
83 views

WordPress script injections [duplicate]

I manage an Ubuntu server that runs a number of WordPress sites. This morning one of them went down and was showing the exception PHP Fatal error: Namespace declaration statement has to be the very ...
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2answers
180 views

Unusal GET requests in my nodejs journal - has my nginx/node been hacked? [duplicate]

Saw this in the journalctl for a service I have: jul 29 12:39:05 ubuntu-18 node[796]: GET http://www.123cha.com/ 200 147.463 ms - 8485 jul 29 12:39:10 ubuntu-18 node[796]: GET http://www.rfa.org/...
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1answer
94 views

Laravel | Why create a public_html folder and link/move it?

I am using laravel on shared hosting. Under my domain in my folder is the laravel app. Now I see online that many people do weird stuff with the laravel public folder, they either move it to a ...
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4answers
2k views

How safe is dm-crypt/LUKS? Would TPM make me more secure in this case?

I’ve been looking to purchase a new laptop and I need to have security in mind. I’ve specifically been looking for laptops with discrete or integrated TPM because it’s been my understanding that TPM ...
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5answers
4k views

What are the potential vulnerabilities of allowing non-root users to run apt-get?

There are two ways I can think of doing this: On a system with sudo, by modifying /etc/sudoers. On a system without sudo (such as a Docker environment), by writing a program similar to the below and ...
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2answers
4k views

Constant POST request spam to /cgi-bin/ViewLog.asp endpoint

I've got a DigitalOcean server that I use for different temporary servers. Lately I've found that sometimes I get a constant spam of the following requests: POST http://127.0.0.1/cgi-bin/ViewLog.asp ...
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1answer
243 views

If someone steals my unencrypted, password protected laptop, would they be able to get into my Google account?

I have a laptop with Ubuntu 20.04 operating system. I am logged into my Chrome browser using my Google account. This means, every time I open my browser, I am already logged into all the Google ...
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2answers
597 views

Encrypt backup files and send them to AWS S3

I have a backup routine via crontab on Ubuntu. This routine generates a compressed tar.gz file and sends it to AWS S3. But I want to encrypt these files and be able to decrypt them when necessary on ...
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4answers
14k views

Aren't keyfiles defeating the purpose of encryption?

I just added a drive to my system which is basically a partition mounted for extra storage. I'd like to encrypt it to protect my data in case of god knows what, and by doing that I'd need to enter the ...
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2answers
674 views

How to detect malicious files or web shell on a vps web server

How is it possible to detect malicious files or web shell on a vps web server? I used to use a shared hosting, and when I tried to upload any malicious code for testing it got deleted automatically. ...
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121 views

How to secure an IoT device

Which is the proper way to prevent users to read sensible information stored inside an IoT device (e.g. source code / private keys...)? Fully disk encryption is of course an option, but is it ...
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1answer
92 views

Loopholes in secured file server

My system to share private data works like this: I rent a virtual server at a hosting company. There I have a self-signed certificate installed. The folder with the files inside is password ...
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1answer
93 views

VPN as a firewall in a public network

My configuration is: allow only OpenVpn traffic and block any other (income/outcome) traffic with UFW on my ubuntu laptop. unreal scenario: let’s say i have ubuntu with chrome version 50 [2016] on ...
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8answers
4k views

Is a firewall enough of a security measure for an Ubuntu server that hosts a website?

I recently got a VPS with Ubuntu on it, and I'd like to start creating a very basic website. However, I don't know what steps I should take to secure this server. I'm new with Ubuntu, new with ...
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1answer
89 views

Are security scrutinies conducted by independent agencies on open source software like Ubuntu or Mozilla Firefox?

Any intentional malware injected into open source software by the same people who are developing them may eventually get known as the source code is open to the public. However, if the code base is ...

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