284
votes
11answers
50k views

How to securely hash passwords?

If I hash passwords before storing them in my database, is that sufficient to prevent them being recovered by anyone? I should point out that this relates only to retrieval directly from the ...
565
votes
21answers
112k views

XKCD #936: Short complex password, or long dictionary passphrase?

How accurate is this XKCD comic from August 10, 2011? I've always been an advocate of long rather than complex passwords, but most security people (at least the ones that I've talked to) are ...
395
votes
3answers
171k views

How does SSL/TLS work?

How does SSL work? I just realised we don't actually have a definitive answer here, and it's something worth covering. I'd like to see details in terms of: A high level description of the protocol. ...
277
votes
4answers
82k views

Do any security experts recommend bcrypt for password storage?

On the surface bcrypt, an 11 year old security algorithm designed for hashing passwords by Niels Provos and David Mazieres, which is based on the initialization function used in the NIST approved ...
195
votes
6answers
25k views

How to store salt?

Nowadays, if we expect to store user password securely, we need at least do the following thing $pwd=hash(hash($password) + salt) then store $pwd in your system instead of the real password. I have ...
67
votes
7answers
39k views

How secure are virtual machines really? False sense of security?

I was reading this CompTIA Security+ SYO-201 book, and the author David Prowse claims that: Whichever VM you select, the VM cannot cross the software boundaries set in place. For example, a ...
34
votes
4answers
2k views

How do I deal with a compromised server?

I suspect that one or more of my servers is compromised by a hacker, virus, or other mechanism: What are my first steps? When I arrive on site should I disconnect the server, preserve "evidence", ...
80
votes
6answers
25k views

Password Hashing add salt + pepper or is salt enough?

Please Note: I'm aware that the proper method for secure password storage hashing is either scrypt or bcrypt. This question isn't for implementation in actual software, it's for my own understanding. ...
211
votes
13answers
21k views

How is it possible that people observing an HTTPS connection being established wouldn't know how to decrypt it?

I've often heard it said that if you're logging in to a website - a bank, GMail, whatever - via HTTPS, that the information you transmit is safe from snooping by 3rd parties. I've always been a little ...
73
votes
17answers
8k views

Does an established ssl connection mean a line is really secure

From the view of somebody offering a webapplication. When somebody connects with SSL (https) to our service and submits the correct authentication data, is it safe to transmit all sensitive data over ...
39
votes
3answers
18k views

What are the career paths in the computer security field?

What sorts of jobs are there, in which organizations, with what sorts of day-to-day responsibilities? What areas are good for folks coming out of school, vs what are good 2nd careers for experienced ...
259
votes
10answers
31k views

Is my developer's home-brew password security right or wrong, and why?

A developer, let's call him 'Dave', insists on using home-brew scripts for password security. See Dave's proposal below. His team spent months adopting an industry standard protocol using Bcrypt. ...
40
votes
2answers
9k views

Amount of simple operations that is safely out of reach for all humanity?

Cryptographic primitives usually assert some security level given as number of operations to mount an attack. Hash functions, for example, give different security levels for collision attacks, ...
53
votes
13answers
11k views

What are the pros and cons of site wide SSL (https)?

What are the pros and cons of encrypting all HTTP traffic for the whole site through SSL, as opposed to SSL on just the login page?
44
votes
1answer
7k views

What should end-users do about Heartbleed?

What should one do about the Heartbleed OpenSSL exploit? mainly talks about what people running websites should do about Heartbleed. What should end-users of websites be doing? Do they need to ...
36
votes
8answers
9k views

How can I reliably erase all information on a hard drive?

As storage technologies change over time, using different encodings and remappings to deal with sector errors, the best way to permanently erase/wipe/shred data changes also. Methods for flash drives ...
197
votes
3answers
46k views

CRIME - How to beat the BEAST successor?

With the advent of CRIME, BEAST's successor, what possible protection is available for an individual and/or system owner in order to protect themselves and their users against this new attack on TLS?
44
votes
5answers
7k views

Why shouldn't we roll our own?

Why shouldn't we create our own security schemes? I see a lot of questions around here about custom crypto and custom security mechanisms, especially around password hashing. With that in mind, I'm ...
295
votes
20answers
49k views

How does changing your password every 90 days increase security?

Where I work I'm forced to change my password every 90 days. This security measure has been in place in many organizations for as long as I can remember. Is there a specific security vulnerability ...
64
votes
2answers
13k views

What are rainbow tables and how are they used?

Where can I find one? Is there a pot of gold at the end? How do I protect against them? From the Area51 proposal This question was IT Security Question of the Week. Read the Sep 09, 2011 blog ...
40
votes
12answers
5k views

How feasible is it for a CA to be hacked? Which default trusted root certificates should I remove?

This question has been revised & clarified significantly since the original version. If we look at each trusted certificate in my Trusted Root store, how much should I trust them? What factors ...
32
votes
4answers
4k views

Are there DRM techniques to effectively prevent pirating?

A question on Skeptics.SE asks whether current DRM techniques effectively prevent pirating: Is DRM effective? The question for IT Security is: Can DRM be made effective, and are there any examples? ...
63
votes
9answers
11k views

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 ...
24
votes
11answers
4k views

Resources to learn about security

I am currently just finishing a undergrad computer science degree, but I know very little about computer security. What are some good resources (aside from this site) to learn the fundamentals of ...
76
votes
3answers
11k views

Is a rand from /dev/urandom secure for a login key?

Lets say I want to create a cookie for a user. Would simply generating a 1024 bit string by using /dev/urandom, and checking if it already exists (looping until I get a unique one) suffice? Or should ...
67
votes
6answers
11k views

How much can I trust Tor?

How much can I depend on Tor for anonymity? Is it completely secure? My usage is limited to accessing Twitter and Wordpress. I am a political activist from India and I do not enjoy the freedom of ...
62
votes
4answers
8k views

Can anybody explain XSS? [closed]

I work programming Enterprise Java applications and do very little web development in 2002. I'm interested in security and like to read articles about it. However, I never fully understand how XSS ...
55
votes
8answers
119k views

How to determine what type of encoding/encryption has been used?

I've looked on this site and on SE. but i couldn't get a handle on this. Is there a way to find what type of encryption/encoding is being used? For example, I am testing a web application which ...
25
votes
5answers
5k views

How to be completely anonymous online?

I recently saw this post on reddit: http://www.slashgeek.net/2012/06/15/how-to-be-completely-anonymous-online/ But the majority argument, both on reddit and on comments on that post seems to be that ...
56
votes
4answers
37k views

What is certificate pinning?

I'm superficially familiar with SSL and what certs do. Recently I saw some discussion on cert pinning but there wasn't a definition. A DDG search didn't turn up anything useful. What is certificate ...
24
votes
6answers
87k views

If someone hacks my wi-fi connnection, what can they see and how?

I have two questions on wifi security: If someone knows my wifi password (be it WEP or WPA) what can they see on my screen? Do they just see URLs I visit, or can they see everything in my ...
182
votes
1answer
58k views

How exactly does the OpenSSL TLS heartbeat (Heartbleed) exploit work?

I've been hearing more about the OpenSSL Heartbleed attack, which exploits some flaw in the heartbeat step of TLS. If you haven't heard of it, it allows people to: Steal OpenSSL private keys Steal ...
65
votes
8answers
7k views

Can anyone provide references for implementing web application self password reset mechanisms properly?

We are implementing self password reset on a web application, and I know how I want to do it (email time limited password reset URL to users pre-registered email address). My problem is that I ...
59
votes
6answers
26k views

Is there a short command to test if my server is secure against the shellshock bash bug?

I did apt-get update; apt-get upgrade -y on all systems I'm running. I'm not sure if my /etc/apt/sources.list is good enough on all of these systems. I would like to quickly check each system again, ...
42
votes
38answers
8k views

What is your way to create good passwords that can actually be remembered?

What are the methodologies which can be used to generate "human" good quality password? They have to ensure a good strength and also easy to remember for a human being.
78
votes
14answers
17k views

Apache Server Hardening

What are some best practices, recommendations, required reading for securing an Apache Server?
34
votes
4answers
16k views

Why is writing zeros (or random data) over a hard drive multiple times better than just doing it once?

Lots of different programs, such as Darik's Boot and Nuke, let you write over a hard drive multiple times under the guise of it being more secure than just doing it once. Why?
39
votes
3answers
13k views

Is it enough to only wipe a flash drive once?

According to the documentation for the "diskscrb" command for wiping conventional hard drives: http://www.forensics-intl.com/diskscrb.html "Conforms to and exceeds the Government Standard set ...
64
votes
10answers
5k views

How do you explain the necessity of “nuke it from orbit” to management and users?

When a machine has been infected with malware, most of us here immediately identify the appropriate action as "nuke it from orbit" - i.e. wipe the system and start over. Unfortunately, this is often ...
40
votes
6answers
13k views

What techniques do advanced firewalls use to protect againt DoS/DDoS?

It is hard to protect a server against Denial of Service attacks, DoS/DDoS. The two simple ways I can think of is to use a server with much resources (e.g. CPU and memory), and to build the server ...
37
votes
5answers
5k views

How do some sites (e.g. online banks) only ask for specific characters from a password without storing it as plaintext?

I thought How can a system enforce a minimum number of changed characters... would answer my question, but it seems this is a different case. When I sign on to my online banking account, I'm prompted ...
320
votes
12answers
52k views

What technical reasons are there to have low maximum password lengths?

I have always wondered why so many websites have very firm restrictions on password length (exactly 8 characters, up to 8 characters, etc). These tend to be banks or other sites I actually care about ...
84
votes
12answers
24k views

Why is it difficult to catch “Anonymous” or “Lulzsec” (groups)?

I'm not security literate, and if I was, I probably wouldn't be asking this question. As a regular tech news follower, I'm really surprised by the outrage of Anonymous (hacker group), but as a ...
25
votes
5answers
3k views

Professional certifications for IT Security

Which credentials of the sub-list of IT certifications (as per the Information Systems Security Association) would be considered MUST HAVE for a IT Security specialist. Information Security CEH ...
40
votes
7answers
12k views

Is there any security threat with open WiFi connection?

For a few days, my mobile device has been able to catch WiFi signals that are within its radius. It's not asking for a password to use the service. So, I'm using the WiFi service whenever I need to. ...
30
votes
1answer
4k views

Are there more modern password hashing methods than bcrypt and scrypt?

This question made me start thinking about password hashing again. I currently use bcrypt (specifically py-bcrypt). I've heard a lot about PBKDF2, and scrypt. What I'm wondering is if there are any ...
23
votes
1answer
2k views

What cookie attacks are possible between computers in related DNS domains (*.example.com)?

Here, several servers in the same DNS domain emit cookies under a variety of settings (scope, HTTPS, Secure) and another host emits a cookie with the same value. Example Suppose a user has the ...
19
votes
4answers
3k views

Why is using salt more secure?

Storing the hash of users' passwords, e.g. in a database, is insecure since human passwords are vulnerable to dictionary attacks. Everyone suggests that this is mitigated via the use of salts, but the ...
15
votes
5answers
2k views

Different strategies for online anonymity and their +/-s?

I saw this question about anonymous web browser, but I wanted to go a little bit more in depth. I prefer answers that take into account how a connection would be traced back, time it would take to ...
26
votes
5answers
3k views

Open Source vs Closed Source Systems

My understanding is that open source systems are commonly believed to be more secure than closed source systems. Reasons for taking either approach, or combination of them, include: cultural norms, ...

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