Questions tagged [operating-systems]

The operating system is the software component that provides abstraction of physical hardware, and provides a generalized model for application software to execute without the need for specific hardware knowledge. Questions on the topic of operating system security should use this tag; you may also like to use one of the [windows], [linux] or [macos] tags.

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Hardening Linux Server

We have already had questions on here about Hardening Apache, Hardening PHP and Securing SSH. To continue this trend I am interested in what steps people take to harden Linux servers. As in what ...
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464 votes
13 answers
103k views

Are passwords stored in memory safe?

I just realized that, in any language, when you save a password in a variable, it is stored as plain text in the memory. I think the OS does its job and forbids processes from accessing each other's ...
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40 votes
6 answers
10k views

Secure Linux Desktop

I'm looking for hints about secure linux desktops. Securing servers is no problem. Most recent Software Updates, run only the services required etc. But what about desktops? I'm thinking about details ...
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35 votes
11 answers
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Vulnerable OS's?

Which vulnerable OS's like for example DVL would you recommend for someone to use for the purpose of pentest/exploitation learning?
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64 votes
3 answers
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How does the Windows "Secure Desktop" mode work?

Can anyone explain (or provide a link to a simple explanation) of what the Windows "Secure Desktop" mode is and how it works? I just heard about it in the KeePass documentation (KeePass - Enter ...
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9 votes
2 answers
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How expensive is it to guess a 15 character password, and should I be worried?

I'm currently using AES encryption (at home) on GNU/Linux (one of LUKS AES-256 variants with xts) and on Windows 7 (Truecrypt) with a 15 characters password (alphanumeric lowercase only plus _). ...
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29 votes
5 answers
15k views

OS with encrypted RAM?

Are there any applications, JIT frameworks or operating systems that focus on encrypted virtual memory, or perhaps virtual machines that do something similar? I know there are processors (albeit old, ...
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16 votes
6 answers
19k views

Is my computer at risk of being hacked when using public Wi-Fi?

I'm sitting at a cafe, using their public Wi-Fi. I don't go on sensitive sites; I basically go to a music site and listen to a live stream, for which there's no login. I don't check my email or visit ...
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81 votes
8 answers
19k views

Risks of giving developers admin rights to their own PCs

I need to convince my internal IT department to give my new team of developers admin rights to our own PCs. They seem to think this will create some security risk to the network. Can anyone explain ...
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40 votes
2 answers
16k views

What is protection ring -1?

Due to the Lenovo firmware ThinkPwn bug I'm trying to understand privileges and rings. If the kernel is Ring 0 and SMM (System Management Mode) is Ring -2, what could be in between that is Ring -1?
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97 votes
13 answers
14k views

Why do we lock our computers?

It's common knowledge that if somebody has physical access to your machine they can do whatever they want with it1. So why do we always lock our computers? If somebody has physical access to my ...
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17 votes
4 answers
6k views

Windows hardening [closed]

Can anyone point me at some good resources on Windows hardening? From 2003 upwards.
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17 votes
5 answers
29k views

Monitoring system calls (in a reliable and secure way)

It there a reliable method of “monitoring” system calls under Linux? There is strace for example to monitor system calls and signals. Is there a way for a process to dodge out of strace? If yes, is ...
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1 vote
1 answer
338 views

Where does the list of trusted content authorities come from when using a web browser?

I was asked "how do browsers know whether or not to trust the certificate from the server it's connecting to" and thought it was a pretty good question. After doing some googling I found two answers: ...
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17 votes
1 answer
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Why is Linux considered more secure than Windows? [closed]

Why is Linux considered more secure than Windows? Is there some sort of recent security report that proves it? I have come to believe that Linux has been safer so far, but now as we have Windows 10, ...
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14 votes
5 answers
10k views

Linux command logging?

Recently someone broke into one of our linux servers as a non root user. An excerpt from .bash_history: [...] perl perl set +o history set +o history set +o history passwd sdfsdf passwd exit I ...
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12 votes
2 answers
979 views

How is UAC a security improvement?

What does User Account Control on Windows offer in terms of security? It's just an extra click to potentially run a virus.
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15 votes
5 answers
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What is the potential impact of the alleged OpenBSD IPSEC attack?

Recently there is a bit of concern over encryption back doors in IPsec and while the status of this has not been confirmed, I don't know what impact something like this might have. For instance, does ...
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9 votes
4 answers
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Is dual-booting an OS more or less secure than running a virtual machine?

I run two operating systems on two separate disk partitions on the same physical machine (a modern MacBook Pro). In order to isolate them from each other, I've taken the following steps: Configured /...
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25 votes
1 answer
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Mac OS X from an IT Security Practitioners' Perspective? [closed]

What does the Mac OS X offer that it has been recently attracting users with IT security focus? There are sites that specifically focus on "hacking" with OSX, such as machacking.net. Defcon has an ...
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13 votes
9 answers
4k views

Is there any asymmetrically encrypted file system?

Is there a file system providing a directory where everybody can write, but only the directory owner can read the files? In theory it could be done by encrypting using the public key while writing, ...
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13 votes
5 answers
5k views

Am I protected from USB autorun malware on Windows 7?

As far as I know, the autorun.inf problem (the possibility of automatically executing code when a USB stick is plugged in) was solved through Windows Updates for XP, and on 7 it is no longer possible ...
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8 votes
3 answers
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Practical non-government uses of Biba, Bell-LaPadula, etc. models

For example, the Biba model is now hanging out in current versions of Windows. Things downloaded from the Internet are tagged as such. Internet (low) stuff can't alter user (medium) stuff which isn't ...
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15 votes
3 answers
7k views

Can you extract memory contents from a hibernated Windows machine?

In a recent discussion about hardware hacks, attacks surrounding Windows hibernate popped up. I am not entirely convinced that it would be viable to get stuff out of the memory saved to disk. When ...
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5 votes
2 answers
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How can I recover encrypted files after system reinstallation

I had a file which contains images and videos, I was using the windows 7 ultimate and I had encrypted the file. Now I have copied that file to my hard disk and format that operating system and again. ...
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12 votes
2 answers
262 views

Does Centralisation Decrease the Probability but Increase the Damage of Exploits?

This question is, perhaps, a tad too abstract for a Q&A site. But it's been playing on my mind for a while, so I'm throwing it out there. Modern systems seem to be increasingly centralised. An ...
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4 votes
2 answers
2k views

Is it possible to defeat the OS detection capabilities of network scanning tools?

Network scanning tools such as nmap have the capability to infer operating system version based upon lower-level system details. EG: TCP/IP stack behavior, etc. Are there any known methods to trick ...
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11 votes
4 answers
1k views

Are exploits platform dependent?

Looking over an overview of the newest published IE exploit, I noticed what I think is assembly. I don't know anything about exploit development, but I know a little about assembly. Seeing that ...
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6 votes
1 answer
4k views

How do I apply a security baseline to Windows 2008 R2?

I've setup a Windows 2008 R2 server with an Active Directory Domain Services role. I would like to apply the Specialized Security – Limited Functionality (SSLF) security baseline to it, but am unsure ...
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4 votes
2 answers
451 views

How can a VM handle a compromised host?

How can I protect a VM build e.g. with LinuxKit, if my host system is compromised? Are there methods available or am I always at the host's mercy? And is it possible to isolate what's going on inside ...
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12 votes
4 answers
9k views

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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4 votes
2 answers
3k views

How do hackers find vulnerabilities in closed source operating systems?

I'm not planning on hacking anything, but I'm just wondering how hackers find vulnerabilities in closed source operating systems such as Windows, since they don't know exactly what the code is doing? ...
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154 votes
14 answers
26k views

Why is the OS obfuscation defense against "It's a Unix system!" not widely implemented?

The Jurassic Park scene referenced in the title is infamous for how ludicrous it sounds to those who are tech literate. But it also illustrates what seems to me to be a glaringly huge hole in web ...
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28 votes
1 answer
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iOS Encryption Details

Following on from this question, what resources are available relating to the technical specifics of how apple implement encryption on their iOS 4.x series devices? The Apple marketing material here, ...
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6 votes
5 answers
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Suggested reading list: OS exploits

In computer security, my areas of interest include x86 processors, binary exploitation and reverse engineering. I'm also interested in the certain aspects of the minix and the linux kernel(memory ...
24 votes
4 answers
21k views

How do I hide the OS I am using from internet sites?

I am currently trying to mask the OS system I am using from the websites I visit. I'm doing this for an added layer of security. How would I go about hiding the OS from websites?
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  • 383
66 votes
4 answers
10k views

Is an up-to-date browser secure on an out-of-date OS?

Windows 7 support will end on January 14, 2020. Assuming that after that day I still use an updated browser, is it true that I'm still safe? Can it "patch" the OS-based security holes? Minor question:...
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  • 1,539
20 votes
7 answers
6k views

How can I protect my computer from my potentially malicious colleagues?

So, I work in this small company (10 people) where we do stuff in programming, for various platforms. I started recently working there (2 months) right after I graduated. My work is not exactly ...
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19 votes
3 answers
3k views

Are passwords in memory?

I have an encrypted HDD (dm_crypt). That's why I store my passwords in a simple text file. I usually copy/paste the passwords from it. Ok! Q: If I open this text file then it goes into the memory. So ...
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11 votes
3 answers
735 views

What security requirements do you have for Domain Administrators?

With regard to managing a Windows network, what security polices and processes do you use? For example Do you require/support Smart Card Authentication? Restrict logins from a particular workstation? ...
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34 votes
2 answers
9k views

Why is there a need to modify system call tables in Linux?

I have been learning about rootkits recently and have noticed this hooking techniques that kernel-land rootkits use in order perform malicious actions. Where a typical hooking operation would be to ...
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  • 373
21 votes
1 answer
3k views

Is it secure to connect to a remote Windows Server using Remote Desktop only?

I have a Windows Server that I login to from my home. I only use the pre-installed Remote Desktop. Is this a secure way to remote login or should I improve it in some way? If I should improve it, ...
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  • 5,053
12 votes
5 answers
7k views

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 ...
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  • 123
11 votes
6 answers
2k views

What is preventing the widespread common use of MAC-type systems?

Overall question What is preventing the uptake of MAC systems such as SELinux/AppArmor in corporate and desktop computing environments? Why don't you think it isn't already widespread? I do not ...
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16 votes
7 answers
6k views

Can hackers detect my operating system?

I've seen people demonstrating the use of BackTrack to attack VMs. In one of the components of BackTrack, it shows the operating system of the targets. Since support for Windows XP is ending soon, I ...
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  • 535
10 votes
2 answers
5k views

Does linux support signed binaries?

I am looking for something similar to what iOS supports. Does it exist in linux? With a secure boot (based in hardware chain of trust), doesn't it make sense to have signed binaries for security? ...
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9 votes
4 answers
6k views

Is online banking more secure on iOS than a desktop computer?

Does Apple's iOS provide a more secure environment for online commerce (banking or shopping) than Windows or Mac OS X? Since the only software that can run on iOS must be vetted by Apple, the ...
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  • 1,126
9 votes
1 answer
16k views

Where and how do operating systems save passwords for user accounts?

Where do operating systems (e.g. Windows) save their passwords? Do they store them in plain text? Do they use hardware modules such as TPM? Are these methods generally considered secure?
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7 votes
1 answer
4k views

How does OS detection work in practice?

I was wondering how OS detection really works on Nmap. I know it is about to send different tcp probes to see how the target machine responds to them. But what kind of probes would distinguish a ...
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  • 801
6 votes
3 answers
849 views

Virtualization as a layer of security for desktop computers?

Given the amount of 3rd party plugins required to browse the web, I've been compelled to virtualize my online habits to gain an additional layer of security. There is of course some obvious drawbacks:...
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