Securing Linux systems and applications; understanding Linux security features.

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Is symlink race a very common vulnerability in UNIX systems

As far as I know, when I am creating a new file or directory in a directory that can be written by multiple users (and thus an adversary can have made a symlink there), the only way to protect myself ...
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2 views

Squid Proxy with Webmin

I want to setup a Internet Access management configuration system to a hotel with ubuntu 12.04 / Squid and webmin. Once user connects a web page for login must come. If credentials are correct he can ...
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1answer
33 views

Ideas on how I can fragment captured network traffic?

I am trying to create a lab environment where I can analyze common IDS solutions (starting with Snort specifically) and their ability to reassemble fragmented IP trains. I have a collection of ...
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1answer
17 views

What security problems does copying .Xauthority to another user present?

If I want to use a GUI application with another user (example: webbrowser), I can copy the .Xauthority file to that given user's home then I can "su - user" and start the GUI app. Question: but what ...
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2 views

Prevent children of process protected by seccomp from having same seccomp protections? [migrated]

I'm writing an application which is protected by seccomp. This application uses fork() and then execvp() to run certain programs. It seems as though any child process of my program will be constrained ...
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55 views

is linux NSA-free? [on hold]

Does Linux have backdoors for 3-letter agency? or 3-letter agencys have to hack to access a computer running linux? I asked it, beacuse i believe close-source programs etc. windows, osx has nsa ...
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12 views

VA Scan for Linux server Running with Apache and SQL [on hold]

I want to do VA for Ubuntu server installed with Apache and SQL. Which open source tool you recommend?
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0answers
25 views

How to identify the script that's sending spam from my server? [on hold]

So, this is what I wanna know. How do I identify the script that is sending spam from my server?. Server is using exim. Maldet scanning did not help much. Any advises ?
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0answers
65 views

Am I a victim of industrial espionage? [closed]

I had a weird experience, that I don't quite know how to explain. My setup is this: I have my desktop machine, which I connect to my company's VPN. On this machine I also run a VirtualBox VM with ...
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22 views

What else can we now do with the new GCC5 to improve codebase hardening [on hold]

Noting the recent question: What is the most hardened set of options for GCC compiling C/C++? Is there anything else that can be shared regarding the new version of GCC, v5 for 32/64bit targets. I'd ...
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0answers
21 views

How do I request a certificate from CEP / CES on a Microsoft CA on OSX or Linux? [migrated]

This article describes how to request a certificate from AD CS (Active Directory Certificate Services) from a non-domain joined windows computer. I would think the same principals apply to non ...
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0answers
23 views

Threats faced by IPC in multi user system [closed]

I am learning about IPC in Linux. I see that Linux is a multi user system and the programs I start run with my privilege (so programs run with logged in user's privileges - euid). But different user's ...
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2answers
70 views

What are the security risks in leaving 'sudo' inside my production code?

I have a script that can only run successfully with root permissions But in development it's really hard to run with root permissions (in my development environment) so I add 'sudo' when ever it's ...
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1answer
44 views

php- is my code secured enough to protect from remote command execution when using shell_exec()?

I am using shell_exec function on the following variables to execute commands on the shell: fname (characters only) fpack(characters only) email (a valid email address) My code is: <?php ...
3
votes
1answer
74 views

Linux/ssh - Forensic question

In a Linux terminal, I made a ssh connection from A to B and I used commands to read some files stored in B. Then I disconnected and I closed the terminal. Is it possible to find on A, informations ...
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2answers
44 views

How to change default cipher in GnuPG on both Linux and Windows?

How can I change the default symmetric cipher used by GnuPG from CAST5 to another? I'm using GPG4Win on Windows, but would also be interested in a solution for Linux.
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3answers
107 views

Can I do hacking using Windows OS? [closed]

I have searched the web a numerous times but haven't found an explicit answer to my question. I've studied (at school and on my own) computer networks for 2 years, doing active programming for 4 years ...
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2answers
74 views

How to test the php vulnerability CVE-2014-3515

How to test if I'm vulnerable regarding CVE-2014-3515? My vendor supplied me with a patch and verified that it installed however I would like to verify that I am no longer vulnerable. My vendor ...
5
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2answers
87 views

Four eyes authentication for command execution on Linux. (OS level) [closed]

I reached the end of the internet with no success, so now I turn to you guys. What I'm after is a way to implement four eyes principle on the OS level for certain commands in Linux. Example : The ...
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0answers
55 views

open ports on a netgear N-150 router; disable SPI firewall? [closed]

How do I open all ports? At least internally, for LAN traffic from 192.168.1.x to 192.168.1.x I want all ports open. Even if it creates a security problem. thufir@doge:~$ thufir@doge:~$ nmap -p ...
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0answers
35 views

Man in the middle attack, bridging wlan interface to virtual wired interface at0

I'm trying to execute a Man in the Middle attack on my mobile phone, I have two wireless cards, one inbuilt in the laptop, running AR9285 atheros drivers, the 2nd is an Alfa AWUS036NHA card with an ...
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1answer
47 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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2answers
111 views

Roommate Frequently Hacked — How Do I Protect My Network/Devices?

If you absolutely had to share a network with a user who had a very lax approach to security and was frequently hacked (1-2x month for over a year now), what might you consider doing to secure your ...
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0answers
12 views

Anomaly - avconv tool getting corrupted randomly [migrated]

I am facing a strange problem with avconv which is a tool for processing videos part of libav-tools package. I am on a local ubuntu server 14.04.1 LTS. What happens is that the avconv tool is ...
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1answer
29 views

Can sshd block IPs with failed attempts or is a tool like denyhosts or fail2ban necessary?

I am only indirectly familiar with denyhosts (and only just discovered fail2ban) and they certainly seem like worthwhile tools. However, after looking through the options for sshd_config I am trying ...
4
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1answer
95 views

Explain the last part of how Mitnick hacked Tsutomu Shimomura with an IP sequence attack

I was reading up on why TCP ISNs need to be randomized, which led me to this write up by Tsutomu Shimomura. I understood how IP address spoofing and predicting the ISN helped the attacker establish a ...
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27 views

Improve the security of a website implementing the least privilege principle [duplicate]

I am a beginner and I am trying to program a secure website to improve my skills and knowledge. I am under Linux and I am using LAMP with php. My website is similar to a social network so people will ...
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87 views

Improve the security of a website implementing the least privilege principle

I am a beginner and I am trying to program a secure website to improve my skills and knowledge. I am under Linux and I am using LAMP with php. My website is similar to a social network so people will ...
3
votes
1answer
140 views

My sendmail started sending spam; what is causing it to do so? [closed]

Today my sendmail service started sending e-mail to various addresses. /var/spool/mail: From MAILER-DAEMON@noxcommunity.com Fri Jan 30 22:15:30 2015 Return-Path: ...
1
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1answer
84 views

Security of LXC compared to OpenVZ

For years, I'm now using OpenVZ on my server, but support discontinued for Debian and Ubuntu, current releases seem to focus on LXC now, which is not a bad idea from the point of comfort. But what ...
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2answers
159 views

How should I deal with adware in chrome on ubuntu?

I use chrome (but also have firefox) on ubuntu 14.04 32-bit. Recently I started getting popups from 'softwareupdaterlp.com'. I had the sense to realize it was not legitimate and I didn't click install ...
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1answer
998 views

Is Java vulnerable to glibc GHOST Vulnerability in Linux?

I see on our RedHat Linux platform that "java" process has dependency over glibc library: [root@hpproliant1 ~]# ldd /usr/bin/java linux-gate.so.1 => (0xffffe000) libpthread.so.0 => ...
1
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1answer
65 views

OpenSSH downgrade attack

I have tried to implement a downgrade attack against the SSH protocol as the first steps (encryption protocols exchange) are not signed, as per RFC4253. The idea is to intercept (mitm) these steps and ...
0
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1answer
48 views

Bogus HostName Causing Suspicion of Man In The Middle

I have servers on a LAN reporting my laptop with a bogus hostname. This is making me suspect a man in the middle attack. Here are some details: From an Ubuntu Linux 14.04 laptop, I logged into an ...
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92 views

Is there any method to prevent/trace ddos attack?

I have a debian linux server which run a few online game services. I have some competitors in this area and i think one of them is behind the ddos attacks. I have full access to the router, so I set ...
2
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2answers
56 views

Linux Repo Security

Can a registered 3rd party repo spoof critical packages (e.g libc6) and have them installed on apt 'upgrade' operations? What are the best ways (configuration) to help manage 3rd party repos to ...
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2answers
94 views

Is there a way to check for “hollow” processes, or malware hidden within “normal” processes

I recently came across an article on the The Verge, which centers around the concept of commercial malware production and how it's used around the world. The article introduced me to a number of ...
2
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1answer
57 views

How does the Samba misconfigured '/etc/passwd' file security bypass vulnerability work?

I just found this vulnerability on http://www.securityfocus.com/bid/36363/references, which affects several samba server 3.0.xx. Can anyone explain more about this vulnerability? How this bypass ...
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2answers
86 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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28 views

Bruteforce with Hydra [duplicate]

I'm trying to use a Hydra script in the following scenario on localhost and Linux: After web form login, my app redirects to another page with header(Location: internalpage.php) I use this syntax ...
5
votes
2answers
546 views

Security of Linux Full Disk Encryption (Ubuntu / Mint) -insecure?

I'm wondering, why is Ubuntu and Mint using SHA1 for Full Disk Encryption? I heard several times that SHA1 shouldn't be used anymore because it is weak and it could be cracked. Could you guys ...
2
votes
1answer
71 views

Upload a file into directory with public write access

I know it is not right to set a permission for the folder as 777, but if it is done so will it be possible to upload a file into that directory without ftp access ? Here is what I mean Lets say the ...
3
votes
1answer
74 views

Key generation: Differences between GnuPG classic, stable, modern?

I plan to create a 4096 bit RSA&RSA key pair: gpg --gen-key --personal-digest-preferences SHA512 --cert-digest-algo SHA512 Is there any difference in generated key quality between versions 1.4 ...
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0answers
57 views

Is there any security risk with adding a **root's** public key to the local user's authorized_keys (so root to login as a user non-interactively?)

Background: I want to try unprivileged lxc containers a try on my small web server (hosting 2-4 users). Since the server is shared among friends, we decided to separate our services from the machine ...
3
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2answers
100 views

Firewall egress filtering / quick whitelisting

Suppose your Aunt or Uncle is easily fooled by phishing attempts and their computer has multiple root kits and key loggers running. Assume their computing habits will never change. Looking at his ...
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86 views

Protecting against bad USB in ubuntu

I am referring to this thread: How to prevent BadUSB attacks on linux desktop Since i want to install ubunto onto a possible infected usbDrive using a live DVD and the installation manager i was ...
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2answers
93 views

Running tails on a corporate computer

Is it safe to run TAILS on a corporate computer? I mean a corporate computer that has hardware cryptography and probably some backdoors; and, by safe, I mean that nobody will be able to recover what ...
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1answer
23 views

SELinux ignoring /etc/sysconfig/selinux directive

I'm running SELinux on CentOS 6.5. In /etc/sysconfig/selinux I have set SELINUX=permissive. But everytime the system starts, sudo getenforce shows SELinux as Enforcing. What could be causing it to go ...
3
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2answers
70 views

How to securely install software on Ubuntu?

How to install a software like Sublime Text on Ubuntu 14.04 LTS and mitigate against a MITM attack? There is a PPA available, but the PPA must be added manually. I don't see any PGP keys or MD5 ...
7
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2answers
167 views

List all files with only arbitrary file path read, but no directory listing nor sudo

I have found a path traversal vulnerability that allows me to read any path on the server that does not require sudo. To fully exploit this, I would like to know which files exist in each directory ...