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396

You are touching a sore point... Historically, computers were mainframes where a lot of distinct users launched sessions and process on the same physical machine. Unix-like systems (e.g. Linux), but also VMS and its relatives (and this family includes all Windows of the NT line, hence 2000, XP, Vista, 7, 8...), have been structured in order to support the ...


118

In some places they have a saying: "opportunity makes the thief". All you're doing by screen-locking a computer is making the cost of hacking it just a little bit harder. Security is an economic good, with a price and a value. The value of locking is somewhat larger than the price of locking it. Sort of like how in good neighborhoods, you don't need to ...


98

Memory isolation Your example wouldn't work on Windows 95, but it did work on DOS and Windows up to 3.11 (not Windows NT). The PC architecture, and the Microsoft series of operating systems, started with the Intel 8086 processor and an operating system (DOS) designed to run a single program at a time. You would run a program, and when you were finished ...


80

Because it wouldn't help. Most keyloggers are installed at the operating-system level, and the operating system needs to have access to the keystrokes. Alt-Tab program switching, using Ctrl-Alt-Del to terminate malfunctioning programs, and detecting keyboard activity to keep your screensaver from activating all require the OS to see keystrokes. There's ...


63

The wording of that sentence may seem a bit worrying because in a way it implies that they have root access as a backdoor that is already installed and in use. The truth is that it was just bad wording from Mark and what he tried to explain is that, yes, they have potential root access to your machine because every package update runs as root and at that ...


55

It's a risk management thing, really. An attacker with a short window of opportunity (e.g. whilst you're out getting coffee) must be prevented at minimum cost to you as a user, in such a way that makes it non-trivial to bypass under tight time constraints. Hitting WinKey+L or clicking the lock button is next-to-zero cost for you as a user. Taking the time ...


54

At every place I have worked (as a contract developer) developers are given local admin rights on their desktops. The reasons are: 1) Developers toolsets are often updated very regularly. Graphics libraries, code helpers, visual studio updates; they end up having updates coming out almost weekly that need to be installed. Desktop support usually gets ...


50

Identify required applications and processes and apply a checklist to either avoid installing them, or worst case uninstall them after the initial build. Here I'm thinking those common culprits which still seem to go on to far too many distros by default! NFS services: nfsd, lockd, mountd, statd, portmapper telnet server and ftp server R services: rlogin, ...


46

file piece ("chunk") hashing is actually an essential, core feature of BitTorrent (the downloaded pieces are immediately and automatically verified), and a part of the BT protocol - the .torrent file contains the hashes needed for verification. So, unless the .torrent file is altered by an attacker (which is a very different issue), the integrity of the ...


45

The "rings" nomenclature (0-3) you usually see these days started with the requested privilege level field in segment selectors as part of the design of x86 protected mode. Back in the day, it was possible to make exclusive sections of the memory space called segments. In "real mode" it was necessary since you only had 20-bit addressable memory. When ...


36

You trust them because they distribute the software that runs your computer. Their processes run as root: you have to trust them because the computer is in their hands, more so than it is in yours. While you are the administrator of the machine, you use their tools to do your administrator tasks. The point he's making is that you can only run an OS ...


34

I work in the consumer electronics arena and security here is somewhat different than in the server environment. Here we have to assume that the product is in a hostile environment. So for subscriber management purposes keys are kept secure. The first line of defence is that the SoC has hidden registers that even the operating system can't actually access, ...


33

There is quite a lot of them: Metasploitable: Currently there are 2 versions. Kioptrix: Currently 4 challenges. Hackademic: Apparently 2 VM, check 1 and 2. pWnOS: Currently 2 challenges. Standalone which you can install directly without VM, this is to hone your Webattack-Fu: OWASP WebGoat Damn Vulnerable Web Application Mutillidae


31

The keyboard to application interface goes through several phases, some of which the OS has little control, and some that is provides explicit hooks into for additional functionality. The basic design goes like this: hardware events are received by driver chains, which then pass messages to the kernel, that then dispatches it to a global hotkey chain, and ...


30

Yes, this is very possible. In fact, support for this is built into the most popular port scanning tool in use, nmap. This feature, OS detection, can be activated by passing the -O flag to the nmap tool. What nmap does is send different TCP and UDP packets to the target and examine the response. By comparing the response to a database of existing operating ...


29

There are a number of reasons why building their "own OS" is not a viable option. 1. Research Cost To built a new OS, from ground up without the use of any existing code would require significant research. Even today, there are only four or five popularly used kernels like Unix , Linux kernel, BSD, XNU and Windows NT. 2. Security through obscurity It's a ...


28

First there was one... Below is a shot of the network management table at Shmoocon this year. That one IBM? That's my work-issued machine that was powered on for an hour because I needed to get some things done while away. It didn't do anything else all weekend. Every single one of us did the rest of the work on macs. Why do all the security guys have ...


26

Any time you execute code acquired from someone that you haven't fully reviewed and it runs on an Internet connected system, there is a risk that the person who wrote or deployed that code could transmit data about your usage to another system. That's true regardless of the OS. So yes it's possible. The question then becomes "has this happened in the past",...


25

Locking your computer prevents surreptitious snooping or alteration. If you don't lock, it is easy for someone to poke around inside your session in such a way that you will not notice it when you return to your machine. The security benefit is real because there is a class of attacker who wants access without leaving any trace whatsoever. For that class of ...


24

This partly depends on the kind of software the dev team is expected to develop. Some types of software are easier to develop without administrative rights than others. For example, you can do a fair amount of web-based Java development using the likes of Eclipse with Maven artifacts, all installed locally (and typically tested on port 8080), without ...


24

At the moment there is no way to easily work out whether to trust specific docker containers. There are base containers provided by Docker and OS providers which they call "trusted" but the software lacks good mechanisms as yet (e.g. digital signing) to check that images haven't been tampered with. For clarification to quote the recently released CIS ...


23

The "Linux Server" space includes a huge range of distributions, each with their own default configuration update strategy, package management toolchain, and approach to default services and open ports. There is also a wide range of deployment scenarios: hardening a web server is quite different than hardening a linux-based router. You may get better ...


23

The reason this isn't done by default is because the previous-generation operating system design didn't have a huge focus on sandboxing and the like, so right now it would require big architectural changes to make such changes work. Mark touches upon those to some extent in his answer, but it boils down to that you can't allow applications to blindly run ...


22

I recommend the following steps, in rough order of priority: Enable automatic updates. This is the best way to ensure you are always running the best, patched version of all software. Turn on a firewall. A simple policy often suffices for desktops: roughly speaking, allow all outgoing connections, block all incoming connections. This is a lot easier than ...


22

Yes. Your colleagues, if they really wanted, could probably access your computer, your personal files, your passwords, your banking account, etc. That's just the way of it. There are any number of ways they could do this, if they wanted to be dishonest and malicious. One simple way would be to install a keylogger (or other spyware) on your machine at ...


21

I'd suggest in additiona to HamZa DzCyberDeV's answer: Pentester Labs exercises which are full VMs as well as full detailed walkthroughs etc. These are great for all skill levels and i've found them most useful.



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