Hot answers tagged

97

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 ...


79

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 ...


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 ...


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 ...


23

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 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 ...


17

Yes, it can be done as (theoretically) every "computing device" is computationally equivalent to every other computing device. Look up the Church-Turing thesis if you are interested. However your question is grounded in practice and in this case the answer is "yes, but it would cost too much". Effort in virtualisation today aims at speeding up the virtual ...


12

If one goes back a few years before Windows, it was pretty much expected that any program running on a microcomputer would "own" the computer. If it wanted certain services to remain usable it would have to leave certain parts of the system alone, but otherwise there wasn't really any need to "protect" anything. Mainframe computers were sufficiently big ...


10

Windows will have full hardware device access while it is running. If the Linux partitions are encrypted the data within them is safe from exposure that way. However malware infections obtained while running Windows could manipulate the bootloader to produce a fake disk encryption prompt that steals your master encryption key. This is fairly elaborate, ...


8

Actually lorenzo's answer does not quite cut it. The Church-Turing thesis only provides us with a model of computing, it can't tell us anything about virtualization because it is not concerned with other aspects of a machine. But there is theoretical analysis for the ability of a machine to be virtualized by Popek et al: ...


8

Good question. When not encrypted, they can indeed affect each other. All you have to do is mount the other drives, or partitions. If you have firmware-level malware, it's a trivial task to get your encrypted disk key. Even when encrypted, you can still access data each way; it just won't be useful until you decrypt it. Without encryption, you don't even ...


7

Trust it as much as any unsigned code that you run on your systems. Containers are just processes with some extra namespace protections on them, so that's all the protections they get. They still talk to the same kernel underneath.


6

Actually, almost all of the CPU on the market, save for the very small ones meant for low-power embedded devices, offer "hardware-enforced isolation". This is called a MMU. Synthetically, the MMU splits the address space into individual pages (typically 4 or 8 kB each; it depends on the CPU architecture and version), and whenever some piece of code accesses ...


5

It's best to consider a Docker container to be the same as running an application on the host system. There are some attempts to lock down the Docker daemon by removing Linux Kernel capabilities, but this is not really a guarantee. If you do run Docker, there are a few things you can do to help mitigate some of this risk. SELinux - Enabling this will ...


5

In essence, I argue it is the same question as whether open source software is trustworthy. But I think the risk of using community Docker containers is somewhat higher at present than the risks of using open source software. First, as you mentioned, there is no signing and verification now. Good open source packaging systems today include this, at least ...


5

On Windows, there is very little protection between applications running as the same user. If you try to take away SetWindowsHookEx, then malware writers will switch to DLL injection and a whole set of other techniques. You could even just draw a transparent window over the targeted application which would have focus and recieve keystrokes, then pass on ...


5

A simple example: The DOS screen-writing capabilities left a lot to be desired. It was routine to simply write video memory directly. You needed to do this to get reasonable performance for anything that does a lot of screen updates and it was absolutely essential if you wanted to write the bottom right cell of the video screen--say, to draw a border ...


5

Windows 8 and 10 have options to reset your operating system to factory defaults, with or without keeping your personal files. Click here to see how to do that Additionally, you can use a utility called eraser to securely erase free space left on the drive. Click here to check out eraser This combination would be the simplest method to accomplish what ...


4

"Average length of time that an announced vulnerability has widespread exploitation", T "Attractiveness of server as a target", A, on a qualitative scale of 1-5 (higher number representing more attractiveness). "Ease of exploitation", E, using the CVE score as a basis of common comparison (T/A) x E = N Considering that T is now considered to be measured ...


4

I just asked a similar question; mine was about how Apple will fix this though, not necessarily what the bug does that causes the phone to crash. As @LvB suggested, it seems to be a bug in the SpringBoard notification text processing, where the program infinitely reads the Unicode string into memory, taking up all the available memory. Then, the SpringBoard ...


4

I complete my own answer after a more in-depth comparison between the OSes I am the more familiar with and which took quite surprisingly different directions... PID randomization was popularized by OpenBSD which added it as soon as 1997. At that time it pursued two main goals: Protect against PID prediction vulnerabilities affecting mostly software which ...


4

For a malicious attacker who tries to alter an ISO file while keeping its hash value identical to the hash value of the "genuine" file, the problem is known as a second preimage attack. No such attack is known for SHA-1 right now; if somebody wanted to compute such a second preimage, he would have to pay a cost of about 2160 hash function computations, which ...


4

In general, yes, booting from a flash drive gives you access to anything that's not encrypted. In this specific case, Tails itself is stopping you. It's voluntarily respecting the permissions declared by the filesystem on the hard disk. This isn't intended to prevent you accessing private files though - it's simply a side effect of the fact that Tails, for ...


4

To expand on the MMU answer, all of the early 80s "personal computer" chipsets started off without that functionality. It has a non-zero cost in chip area and delay to memory, a cost that was a lot higher in those days on the 3 µm chip process. Remember that we can fit about 20,000 transistors today in the space of one back then. The 8086 and 68000 (as used ...


4

Everyone has read access to system32, but only administrators have write access. If you want to write to system32 as a Windows user, you need to conduct what is called a privilege escalation which elevates a normal user to admin. This can usually be prevented by proper user management and configuration since there are many possibilities to elevate ...


3

Put an actual computer in a physical sandbox environment. The computer itself isn't a sandbox and don't virtualize anything. Need active directory? Put active directory in the sandbox environment. Do your tests, verify what has changed, review computer and network logs. This is more practical than building a sandboxed OS which limits normal hardware ...


3

Realistically, the risk reduction options available will most likely not be cost effective. Especially considering those servers may be upgraded within the year. Two options that come to mind are network segmentation and application white listing. Symantec has a nice guide entitled, "Windows Server 2003 Migration: A Guide to Effectively Mitigate Risks". ...


3

From the nmap documentation: Another cause of duplicate fingerprints is embedded devices which share a common OS. For example, a printer from one vendor and an ethernet switch from another may actually share an embedded OS from a third vendor. In many cases, subtle differences between the devices still allow them to be distinguished. But ...


3

OS access permissions of files at best prevent you from reading the files while that OS is running. Besides booting from a USB drive, you can also remove the drive and attach it to another computer as a data drive to access the files. The best means around this is to encrypt your data. Note that some enterprises implement policies that are aimed at ...


3

So which is it? Does both the operating system and browser come with a built in list of trusted certificate authorities and if a certificate is signed by an entry in either one of the list it's trusted? It depends. Windows and MacOS X come with a their own certificate store filled with the trusted CA and both the builtin browsers (i.e. Internet ...



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