Securing Linux systems and applications; understanding Linux security features.

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What is the Linux Kernel attack surface?

What is the full Linux Kernel attack surface ? meaning what are the vectors through which untrusted or unprivileged access interacts with the Kernel. For instance, system calls are an attack vector, /...
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rdp connection with netcat pivoting

I want to connection from local computer to another local computer. I have 3 machine. for example A: 192.168.1.50 -> in local windows machine B: 50.3.52.110 -> linux server C: 192.168.5.25 -&...
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17 views

wpa_passphrase command encrpyting psk

Does the wpa_passphrase command turn an ASCII string into hexadecimal and what is the benefit of doing so? Is the psk sent in the header of packets? Can it be easy to sniff if it's in a string format? ...
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14 views

HPET effects on CSPRNG for Linux OS

HPET or High Precision Event Timer is a hardware built-in clock source available in most processors. I would use the computer to generate CSPRNG and do cryptographic operations. My question is: Is ...
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1answer
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Are the Linux community/universe repositories significantly less safe then the main repositories?

If so what makes community/universe less safe? Is there less testing or is it simply less safe because more people could put malware in them.
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685 views

Removing a Redirect Virus from Fedora Linux

Despite several attempts listed below certain websites are getting redirected to a certain ad website automatically, out of the blue on linux. When some website starts redirecting to this ad website ...
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1answer
559 views

How does SELinux affect the Linux Kernel networking stack?

I'm interested in how SELinux effects the processing of packets through the networking stack. I've found the following questions and answers: Network policies under AppArmor/SELinux Filtering ...
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1answer
67 views

What is the best way to upload a file securely? [on hold]

What is the best way to upload a file securely? My client is a .NET Desktop Application and server is Apache Tomcat running JSP Files, running on a Linux OS.
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Why is plain dm-crypt only recommended for experts?

I am curious about the following claim from the Cryptsetup FAQ: 2.4 What is the difference between "plain" and LUKS format? First, unless you happen to understand the cryptographic background ...
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40 views

Does stack (UNIX x86, x86-64, ARM) grow up or down, buffer overflow tutorials wrong explained?

when I read something about buffer overflows on the stack, the most or some tutorials show me examples about overwriting local variables (pointers) and then overwriting pointers in the global offset ...
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295 views

About SHA1 in default Disk Encryption in Linux

Link to the thread: Recommended options for LUKS (cryptsetup) I wonder what's the exact difference between SHA1 and SHA512. I know that SHA512 has a longer key but I've read that it doesn't matter ...
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2answers
539 views

How exactly does this Flash malware function on Ubuntu?

In this video, an experienced Ubuntu user manages to infect his system with some sort of malware. This is the first example I've ever seen of truly successful malware in the wild aside from privilege ...
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39 views

Why RedHat Linux has obtained separate FIPS 140-2 certificates for OpenSSL , NSS, Kernel Crypto API etc?

I am wondering why RedHat Enterprise has obtained separate FIPS 140-2 certificates for OpenSSL , NSS, Kernel Crypto API etc. Is it not enough to have FIPS 140-2 certification for only one ...
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1answer
106 views

Methods root can use to elevate itself to kernel mode

When most Linux users hear "root", they think of the maximum possible privilege on a computer. Some even think that root runs in ring 0. But in reality, root is just a regular user running in ring 3, ...
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23 views

Kali Linux: wrong kernel. What to do? [closed]

What does this mean : Unable to boot- please use a kernel appropriate for your CPU what do I have to do ?!
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3answers
99 views

Does a reverse proxy pass keep the backend server anonymous?

If I have an NGINX server at 1.1.1.1 and in the NGINX server you have the config that forwards on http traffic to 2.2.2.2: upstream 123 { server 2.2.2.2; } server { listen 80 default_server; ...
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3answers
5k views

Do simple Linux servers really need a non-root user for security reasons?

Playing devil's advocate, Let's assume I purchase a Linux server from a hosting provider. I am given a password for the root user and am told I may login using SSH. The only purpose this server has ...
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Tboot TXT boot failed [migrated]

I have followed Fedora's wiki to setup launch control policy with TXT enabled. here is the link: http://fedoraproject.org/wiki/Tboot After Tboot issues GETSEC, it reboots without any error message. ...
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1answer
95 views

How use snort with local.rules in offline mode?

I'm using SecurityOnion distro and I would to run snort on my pcap files. Is there a way to specify just one rule? I couldn't understand whether local.rules is used. How can I show only the result ...
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61 views

Very fast and efficient way to check that contents of the directory weren't modified

I need a way of determining whether contents of a folder containing some executable stuff have not been modified in any way a moment before I decide to execute the whatever is in it. Check every time ...
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33 views

Using hash of root password to encrypt files/folders (Debian 8 Linux)

I have an application that requires unattended decryption of files/folders. Would it be possible to utilize the hash of the root password to prevent an attack where a malicious user changes the root ...
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12 views

Differences between Intel TXT and Linux IMA

I understand that Intel TXT provides a Dynamic Root of Trust Measurement (DRTM). Does the Linux integrity measurement architecture do logically similar things? If not, what are the differences?
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2answers
70 views

How secure is it to use secret directory names to share files on unix?

There is an old trick on unix systems to allow a non-root user to "securely" share files with particular other users. mkdir share chmod 711 share #others can traverse share, but can't list its ...
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3answers
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How can I kill minerd malware on an AWS EC2 instance? [duplicate]

I have an AWS EC2 instance running RHEL 7.2 which seems to have been hacked by a BitCoin CPU Miner. When I run ps -eo pcpu,args --sort=-%cpu | head, it shows that there is a CPU miner that's taking up ...
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How can extended file permissions (ACLs) be managed by Kerberos in Linux?

Is it possible to have extended file permissions (ACLs) in Linux be managed (enforced?) by adding permissions authenticated by Kerberos?
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2answers
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How are the disk encryption keys protected when a laptop is locked?

If you were installing such operating system as Ubuntu, you would have seen an option to encrypt your home directory or the whole hard drive with an AES 256bit cipher. When your laptop is totally ...
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1answer
87 views

Robots trying to login to Azure VM when SSH port is closed in manager

I have many robots trying to do SSH login in a Azure VM. In the resource manager SSH is disabled but attacker IPs are public, as you can see below, where I copy a log for auth.log (I have an Ubuntu ...
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3answers
41 views

Node.js REST server running as root

I am building a REST API server using Node.js and Express, that will allow you to turn any Linux server into a NAS. I have several fileExec which basically spawns a shell and executes a BASH command (...
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1answer
3k views

Has malware ever been found in a package from a large Linux distribution and what is done to prevent this from occurring?

I am wondering exactly how safe are the Arch, Ubuntu, Mint and Manjaro repositories. What testing is done to ensure that a trusted user does not place a virus in a package, and how often?
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Why do websites still suffer from OS injections if by default web-servers are not assigned a shell?

So even if there is some poor php written which allows a shell_exec() and that someone disabled safe mode on it, what exactly are the risks? Do admins just change the default group or are most attacks ...
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2answers
38 views

DB Security from system admin perspective

I need some clarity in terms of Security involving Linux Admins and DBAs. Oracle DB on an Enterprise Linux server. I want to ensure none of the contractor team be able to tamper database and its ...
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1answer
35 views

Security implications of using SETCAP CAP_NET_RAW

In order to get around the 'problem' of applications requiring root privileges to run, I'm using: sudo setcap CAP_NET_ADMIN+ep "$(readlink -f /usr/sbin/app)" sudo setcap CAP_NET_RAW+ep "$(readlink -f ...
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1answer
19 views

Does altering the routing table to my hub defeat the purpose of a VPN?

I am running a VPN on my server with openvpn. When running openvpn I have a shell script that runs afterwards: ip rule add from 192.168.0.19 table 128 ip route add table 128 to 192.168.0.0/24 dev ...
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104 views

What infection vectors is Trojan.Linux.BillGates usually delivered with?

I just discovered that my server is infected with Trojan.Linux.BillGates.G and is being used to launch DOS attacks. It surprises me as the server is kept up-to-date (CentOS/Tomcat/CouchDB) as much as ...
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1answer
185 views

Block OS fingerprinting without using iptables?

I have a Linux machine connected to a Windows 98 PC on port 104. Now I want to block the OS fingerprinting using nmap for the windows 98 PC. I tried using iptables (blocking that particular port) but ...
66
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3answers
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What is the difference between authorized_keys and known_hosts file for SSH?

I am learning the basics of SSH protocol. I am confused between the contents of the following 2 files: ~/.ssh/authorized_keys: Holds a list of authorized public keys for servers. When the client ...
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What can an attacker do with Bluetooth and how should it be mitigated?

What are the security risks of Bluetooth and what technologies and best practices should be used to protect my device? What can an attacker do once a malicious device is paired with mine? ...
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5answers
1k views

Securing Debian Apache PHP server

I have a Debian Apache PHP server. I want to secure it after the classic installation process. My usual steps are : list items update all packages remove all unnecessary services like named, ...
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1answer
96 views

Linux file information leakage

What information is kept in a linux file about the user and/or system that created it? I want to make some files publicly available, posted on another server such as GitHub or FTP, but I'd rather the ...
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28 views

Get data file off critical database host

Re-wording this question to hopefully be more understandable. Thanks for the feedback. We have a data warehouse which sits in our production environment. Our data engineers can get to the host via ...
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1answer
48 views

Defense-In-Depth With Common Security Controls

Many operating systems implement system capabilities, Posix access controls (DAC/ACLs) and mandatory access controls (SELinux), each using different underlying security controls to provide individual ...
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3answers
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Is it safe to manually patch security bugs in an outdated system, that is no longer supported?

How do I manually patch security bugs safely without damaging the system for information security purposes on my Ubuntu system that I am running on my Nook Simple Touch (2011 Nook)? I need to find ...
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1answer
31 views

How to best manage multiple applications using the internet with Firewall

Im not new too Linux (Ubuntu 14.x) however I must admit that I have never bothered with a Firewall until now. Im currently using Ubuntu's inbuilt firewall (UFW) with a graphical plugin (GUFW), which I ...
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1answer
27 views

On a Linux server, is it safe to store a script containing DBI credentials in the cgi-bin of the DocumentRoot?

I understand that (at least on Linux servers) the custom is to create a ScriptAlias from a cgi-bin directory located inside the DocumentRoot (i.e. /var/www/html/cgi-bin/) to a cgi-bin directory ...
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2answers
124 views

Is Qubes OS more secure than running a set of activity related VMs?

I'd like to skip the argument about Linux being more secure than Windows, and purely focus on the security boundaries between Host OS and VMs. Is Qubes OS theoretically more secure than say - Windows ...
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3answers
91 views

Can I test my own network?

I'm currently trying to enter the field of information security and I was just wondering if there was anything barring me from testing my own network for security vulnerabilities? I only have a couple ...
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1answer
1k views

Snort even though working properly does not report majority of rules

I have installed Snort 2.9.7.0 and it does not detect majority of attacks, such as nmap port scans, downloading exe files, opening documents containing keyword "root". I use Snort together with ...
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How to get MAC addresses of devices which are not in the network

Can I get MAC addresses of devices (mobile phones) which are near to my network but not connected to it? (Linux) I have been trying to get the MAC addresses of devices connected to my network through ...
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web view addjavascriptinterface exploit

I have been banging my head around this for almost 56 hours now (+/- a few that I took out to have a couple of naps and RedBulls) and have not been able to get anywhere with it so far. I am trying ...
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How to detect Meterpreter and similar malware?

Is it possible to find Meterpreter or similar malware which doesn't modify the hard disk but is only stored in RAM? Most common anti-rootkit software like rkhunter and chkrootkit don't find it.