691
votes
22answers
140k 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 ...
527
votes
3answers
265k 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 ...
429
votes
19answers
55k views

How can I explain SQL injection without technical jargon?

I need to explain SQL injection to someone without technical training or experience. Can you suggest any approaches that have worked well?
385
votes
11answers
75k 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 ...
370
votes
14answers
60k 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 where I actually care ...
362
votes
21answers
69k 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 ...
335
votes
4answers
106k 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 ...
315
votes
13answers
62k 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 ...
310
votes
12answers
55k views

Is it bad practice to use your real name online?

On some accounts I use my real name on-line (Google+/Facebook/Wikipedia/personal blog), others (Q&A/Gaming) I use an alias. My question is: Security and privacy wise, what can people do with my ...
299
votes
10answers
36k 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. ...
271
votes
22answers
293k views

I found that the company I work for is putting a backdoor into mobile phones

I have found out recently that the remote assistant software that we put in a smartphone we sell can be activated by us without user approval. We are not using this option, and it is probably there ...
265
votes
7answers
212k views

RSA vs. DSA for SSH authentication keys

When generating SSH authentication keys on a Unix/Linux system with ssh-keygen, you're given the choice of creating a RSA or DSA key pair (using -t type). What is the difference between RSA and DSA ...
250
votes
13answers
29k 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 ...
242
votes
7answers
38k 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 ...
215
votes
3answers
51k 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?
211
votes
11answers
32k views

How to explain Heartbleed without technical terms?

Most of my friends who are not experienced in computers want to know what Heartbleed is and how it works. How would one explain Heartbleed to someone without a technical background?
211
votes
20answers
43k views

How can someone go off-web, and anonymise themselves after a life online?

With data mining tools like Maltego and other correlation tools for large data sets, if we conduct any transactions online assume that these can all be collated to build a good picture of what we do, ...
206
votes
4answers
88k views

SSL3 “POODLE” Vulnerability

Canonical question regarding the recently disclosed padding oracle vulnerability in SSL v3. Other identical or significantly similar questions should be closed as a duplicate of this one. What ...
201
votes
7answers
36k views

What's the rationale behind Ctrl-Alt-Del for login

Why is Ctrl+Alt+Del required at login on certain Windows systems (I have not seen it elsewhere, but contradict me if I'm wrong) before the password can be typed in? From a usability point of view, ...
192
votes
1answer
65k 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 ...
188
votes
18answers
15k views

Passwords Being Sent in Clear Text Due to Users' Mistake in Typing it in the Username Field

Upon reviewing the Logs generated by different SIEMs (Splunk, HP Logger Trial and the AlienVault platform’s SIEM) I noticed that for some reason quite a few users tend to make the mistake of typing ...
187
votes
5answers
111k views

What is a specific example of how the Shellshock Bash bug could be exploited?

I read some articles (article1, article2, article3, article4) about the Shellshock Bash bug (CVE-2014-6271 reported Sep 24, 2014) and have a general idea of what the vulnerability is and how it could ...
183
votes
3answers
175k views

What's the difference between SSL, TLS, and HTTPS?

I get confused with the terms in this area. What is SSL, TLS, and HTTPS? What are the differences between them?
180
votes
7answers
38k views

Why would you not permit Q or Z in passwords?

Jetblue's password requirements specify that, among other stringent requirements: Cannot contain a Q or Z I can't fathom a logical reason for this, unless it were say, extremely common for the ...
171
votes
3answers
27k views

Don't understand how my mum's Gmail account was hacked

My mum (on Gmail, using Chrome) received an email from a friend's Hotmail address. She opened the email (very obviously a phishing email) and clicked a link in it. This opened a webpage with loads of ...
166
votes
3answers
13k views

What is the purpose of “gibberish” comments posted to my blog?

Fairly frequently, the contact form on my blog gets comments that look similar to this (each field represents a text box users can enter into the HTML form on the blog): Name: 'ceguvzori' Email: ...
165
votes
8answers
74k views

Why not use larger cipher keys?

RSA Security commonly uses keys of sizes 1024-bit, 2048-bit or even 3072-bit. And most Symmetric algorithms only between 112-bit and 256-bit. I do realize that the current keys are secure enough for ...
165
votes
7answers
18k views

How do certification authorities store their private root keys?

Knowledge of a CA private key would allow MitM attackers to transparently supplant any certificates signed by that private key. It would also allow cyber criminals to start forging their own trusted ...
157
votes
12answers
36k views

How is an ATM secure?

I'm curious why an ATM computer is considered secure. The general adage of "If an attacker has physical access to my machine, all bets are off," seems to not apply in this circumstance (since ...
149
votes
18answers
15k views

What is a good analogy to explain to a layman why passwords should be hashed?

Note: This is not an actual situation I'm currently in. Assume your boss is one of those old-fashioned computer-illiterate managers and wants to store the passwords in plaintext to simplify ...
146
votes
8answers
23k views

Why are salted hashes more secure?

I know there are many discussions on salted hashes, and I understand that the purpose is to make it impossible to build a rainbow table of all possible hashes (generally up to 7 characters). My ...
146
votes
5answers
33k views

Why are chips safer than magnetic stripes?

After the recent Target hack there has been talk about moving from credit cards with magnetic stripes to cards with a chip. In what ways are chips safer than stripes?
146
votes
4answers
26k views

How does Windows 10 allow Microsoft to spy on you?

Windows 10 is perhaps the most Internet-connected and cloud-centric operating system released by Microsoft to date. This, of course, has caused many users to be concerned about how the OS respects ...
144
votes
8answers
26k views

What are the implications of NSA surveillance on the average internet user?

It would appear as though the tinfoil hat-wearing were vindicated today, as news broke of the true scale of the U.S. government's surveillance of its citizens' online activities, conducted primarily ...
141
votes
4answers
16k views

Is there anything preventing the NSA from becoming a root CA?

There are now tons of Certification Authorities (CAs) that are trusted by default in major OS's, many of which are unrecognizable without online lookup or reference. While there have been attempts ...
135
votes
9answers
27k views

Is “the oft-cited XKCD scheme […] no longer good advice”?

I was stumbling around and happened onto this essay by Bruce Schneier claiming that the XKCD password scheme was effectively dead. Modern password crackers combine different words from their ...
135
votes
5answers
18k views

Does Facebook store plain-text passwords?

I was about to reset my Facebook password and got this error: Your new password is too similar to your current password. Please try another password. I assumed that Facebook stores only password ...
132
votes
9answers
74k views

Is Adblock (Plus) a security risk?

My email-provider's website (http://www.gmx.de) recently started linking to the (German) site http://www.browsersicherheit.info/ which basically claims that due to its capabilities to modify a site's ...
130
votes
11answers
14k views

What alternatives are there when SSH is being actively filtered?

Unfortunately our government filters the SSH protocol so now we can't connect to our Linux server. They do the filtering by checking the header of each packet in the network layer (and not by just ...
128
votes
4answers
72k views

What exactly does it mean when Chrome reports 'no certificate transparency information was supplied by the server?'

When visiting Gmail in Chrome, if I click on the lock icon in the address bar and go to the connection tab, I receive a message 'no certificate transparency information was supplied by the server' ...
127
votes
11answers
41k views

Why are hash functions one way? If I know the algorithm, why can't I calculate the input from it?

Why can't a password hash be reverse engineered? I've looked into this ages ago and have read lots on it, but I can't find the explanation of why it can't be done. An example will make it easier to ...
123
votes
16answers
13k views

What should I do when my boss asks me to fabricate audit log data?

My boss just asked me to create a fictitious log entry to say that a user's account was updated before it was, to win a dispute. I feel this is not right because I am trying to start a career in ...
122
votes
9answers
14k views

Is Google spying on all of us?

I am curious because, I experienced something bizarre recently. About a month ago, someone asked me to find out a price for a T-shirt printing machine, and probably for the first time, I pressed these ...
121
votes
3answers
16k views

This JavaScript code is injected on my hotel Wi-Fi: should I be worried?

While connected to my hotel Wi-Fi, visiting the URL http://www.google-analytics.com/ga.js results in the following content being served: var ga_exists; if(!ga_exists) { ga_exists = 1; var ...
120
votes
2answers
77k views

What is the difference between https://google.com and https://encrypted.google.com?

Is it there any difference between the encrypted Google search (at https://encrypted.google.com) and the ordinary HTTPS Google search (at https://google.com)? In terms of security what were the ...
120
votes
8answers
13k views

Are “man in the middle” attacks extremely rare?

In "Some thoughts on the iPhone contact list controversy and app security", cdixon blog Chris Dixon makes a statement about web security Many commentators have suggested that a primary security ...
117
votes
8answers
50k views

Is BASIC-Auth secure if done over HTTPS?

I'm making a REST-API and it's straight forward to do BASIC auth login. Then let HTTPS secure the connection so the password is protected when the api is used. Can this be considered secure?
110
votes
9answers
13k views

How can PayPal spoof emails so easily to say it comes from someone else?

When I receive a payment in PayPal, it sends me an email about it (pictured below). The problem is that the email is shown to be coming from the money sender's email address and not from PayPal ...
108
votes
7answers
8k views

How do I report a security vulnerability about a trusted certificate authority? [duplicate]

I stumbled across a huge security vulnerability in a Certificate Authority that is trusted by all modern browsers and computers. Specifically, I am able to get a valid signed certificate for a domain ...
108
votes
5answers
55k views

What should a website operator do about the Heartbleed OpenSSL exploit?

CVE-2014-0160 http://heartbleed.com This is supposed to be a canonical question on dealing with the Heartbeat exploit. I run an Apache web server with OpenSSL, as well as a few other utilities ...

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