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If I am trying to destroy a single file, what is the best method?
shred -uvz -n500 file
dd if=/dev/null of=file
dd if=/dev/zero of=file
I hexdumped a file that was in the middle of shredding, and it was appropriately mangled with what shred said it was writing, but is it secure?
For the sake of this experiment, let's a... |
I have recently been reading about the DRM measures on commercial bluray disks, in particular BD+. It seems that this technology involves Java software running in a virtual machine, with full access to physical hardware and the ability to run native code. This appears to be the case for standalone bluray players, but w... |
I want to make my email address available on my website and I was wondering if there was any point in using the "(at) (dot)" convention these days. If I was writing a script to trawl for email addresses it would definite contain a match criterion for this. Similarly, for the same reasons it seems unlikely that using th... |
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 dictionaries: [...]
This is why the oft-cited XKCD scheme for generating passwords -- string together individual words like "cor... |
There are some people saying that people should use an antivirus software on Mac. And there are thousands of people claiming that Macs don't get viruses (under this term I mean spyware / malware as well), some even say that it's just a trick from antivirus companies to say that there is a need for antivirus.
Honestly,... |
I wonder what are the main registry windows keys malware target often ?
I would love to code a program that will check the state of those windows registry keys for eventual modifications by malware.
|
A few days ago I was searching YouTube and I noticed an "outlier" video poped up in the suggestions list. This video had nothing to do with the topic being searched, but instead it was based on a previous search that was requested from this same computer two weeks ago.
This was impressive considering the situation dif... |
On Windows (XP, 7, 8, NT ...): can .dll files be modified (in any manner) by benign programs/software already installed/running on the computer ?
|
I want to built some short urls for uploaded files and links on my own server. Simple enough, I upload files and my script returns me a link. On access, the link is translated to the file and download starts. Because it's modern, I want my links short and not so UUID4-like, because they are very long.
I do not want th... |
In an authentication protocol, S has a public/private key pair known to C, and S and C have established a secure channel (for example, using DH or ECDH, or any other key exchange protocol). C wishes to determine whether the peer over this secure channel possesses the private key.
In ECDSA, the key pair is an elliptic c... |
I have some HDDs which are encrypted to what I think is a decent standard.
I want to lock these away in a remote storage facility, but am a little worried about EMP/Magnetic stuff from wiping the HDDs.
I will be backing up the HDDs, but wanted to know if there is cheap easy way to protect the HDDs from EMP/Magnets from... |
One of my friend challenged me that if my laptop is turned on then he can attach a device to it, just like in movies which will copy all data of my computer to his hard drive without touching a single key on my laptop.
My question is that is it possible and even if he gets data from hard-drive can he decode it, and the... |
I am a CS student, and am considering competing in the National Collegiate Cyber Defense Competition. Although I have a fair amount of experience in programming competitions (e.g. ACM at High School level, and various online competitions), I have never really considered information security competitions and/or study.
... |
I am redirecting URLs to a virtual machine (Windows operating system) to check if there is malware on the website i want to visit (JavaScript attacks, drive-by download attacks, infected pictures/PDF files or executables embedded on the webpages ...).
In the case there is a webmalware embedded on one of the webpages: ... |
I'm developing a kind of standard web-application, to be hosted internally on few customer's servers (not a public service, startup or anything like that). A kind of CMS, e-learning platform or something close to that. Because this is an internal project, customer had given me quite a large decision field and did not s... |
I know that there are already tools out there to generate cryptographic random number, but I was wondering if using AES could do the same.
For example, I have a secret key for AES on my server and a counter in my database. Each time I want to generate a random number I increment the counter then encrypt it with AES usi... |
My Exchange Admin is setting up 2013, and it is set to block txt file attachments specifically (as well as others).
I have tried searching for risks associated with txt attachments but could not find any. Are there any risks I need to be aware of surrounding txt attachments?
EDIT
The Admin did not set up the rules for... |
Within the last week, I've received 3 phone calls at 3 different locations from technicians who are calling "from Microsoft" about "Windows problems" that they've detected on my PC.
Which they haven't because scam. And it was only good luck that I was visiting my parents when they called them. I've since warned them ... |
An organization requires employees to use 2 person authentication in some scenarios. That is, when accessing, say, a server, secret knowledge from 2 people should be used for authentication. No one person should ever have access to the server alone.
Question: What implementations of this requirement are possible?
This ... |
From what I understand, the JSON-P technique generates a script tag into the DOM of an HTML page to get across the single-origin restrictions imposed on the XMLHttpRequest JavaScript API for AJAX calls to web services not supporting CORS. Usually, the script embedded in this way only contains a callback and in this way... |
When interaction between the user and the operating system is too slow (Windows become slow in responding to different user's request): what parameters could we check (and that we could use within a program coded in any programming language) in order to say for sure that the computer running this Windows operating syst... |
I have been using GUIDs as un-guessable tokens in various situations for some time. I came across this question/answer which seems to suggest that while this is ok in some situations, it should not be done where security is a significant concern.
Typically when I am trying to understand a vulnerability, I will create ... |
Or are certs both host- and port-specific (excepting wildcard certs)?
I would assume they aren't, because they're supposed to verify a domain, but at the same time I've never seen anyone run HTTPS on any port other than 443, and I've only seen X.509 certs used in conjunction with HTTPS, so despite the fact that the ans... |
When a system is suspected to be infected, one of the measures often recommended for cleaning the system (without actually taking the "nuke from orbit" approach) is to scan the drive with anti-malware tools from a known-trustworthy system. The way this is normally accomplished is by removing the drive from the suspect ... |
There are some optional cases in SSL/TLS where server can demand the certificate of the client. Can anyone give me any example regarding this?
Thank you.
|
Imagine you have a private RSA-key on your computer encrypted (through PBKDF2, AES-CTR, HMAC256) with a password, now if the user would like to tick "Remember Password", what is the most secure way to save/remembmer the password? Obviously it's not storing it in plaintext in the local directory.
One option would be to ... |
I have a PGP signature of a known message. However, I am not sure who signed it.
Can I get the public key - or, at least, the fingerprint/other way of searching for it on a public keyserver - just from the message and a signature?
Example: I have this message/signature from here https://futureboy.us/pgp.html
-----BEGIN... |
I read the question about the relevancy of the xkcd password creation algorithm.
Would it be more secure if you used a string of common words with a function that only you knew that would rearrange the characters of said common words?
Define a string of common words and a function f that rearranges the characters in th... |
There are a bunch of people in the anti-surveillance movement who are virtually demanding that I enable SMTP STARTTLS support in my environment, in order to enable opportunistic MTA-to-MTA encryption. The same anti-surveillance people are meanwhile complaining that OpenSSL is poor-quality code with a high likelihood of... |
Is there any need to penetration test a GoogleAppEngine solution? Or will it be protected by googles existing infrastructure?
|
I am about to push hard against the powers that be and strongly recommend that we shift our many (20+) consultants from direct public access to RDP & SSH to VPN clients (connecting to a VLAN/subnet that has restricted access to only necessary resources).
Given that we have a third-party SOC managing an IDS and monitori... |
I have created a REST api, and now i'm thinking about authentication. I want the mobile application's flow for the user to be very simple: only having to enter a username and then this username together with 'some password' will be used to authenticate the user on every api call (using header fields, over SSL).
Is th... |
On my website I have a password reset page that users can use if they have forgotten their password. On this page they can enter their username or their email address and hit "reset" which will send them a link to reset their password.
If they have entered an incorrect username or email, should I let them know that it ... |
I'd like to know if giving access to Intel version of /dev/kvm on Linux to a user that just wants to spawn VMs gives him any extra privileges. That is, are her VMs subject to process scheduling just like other processes? Does it automatically grant direct access to any devices or memory?
|
Sorry for this stupid question but i'm thinking about what an attacker can do with a non persistent XSS attack on a website?
An attacker can try to phish me with a malicious url, steal my cookies or my history etc... but does he also need my intervention or a human interaction for his attack?
What else he can do with n... |
One of my colleagues is working on securing OAuth 2 client IDs and secrets for our OAuth server and he has come up with this scheme where he would not only use UUID v4 to generate random values, but also bcrypt them. Another colleague asked what's the purpose of bcrypt-ing them, to which he got the answer that just UUI... |
let me explain my problem.
The wifi on my macbook suddenly stopped working so tried to use my usb wifi adapter on a linux VM.
But the funny thing is that nothing works on the guest vm either...
Well funny thing because, I get an IP from my DHCP and I can connect to the internet, but only to google's websites!
exemple: ... |
I'm currently building an authentication module and I've got a question. I have set up a server with an API and want my users to authenticate to this server, but I use AngularJS for the site. Everything with AngularJS is client side, so I was wondering how to set the user ID without anyone being able to just change it ... |
Honesty commands me straight away to say that I'm not a professional, but I'm fascinated by data encryption. This algorithm won't be used in production code, so please don't flood me with "Don't design your own crypto", I know. I apologise in advance if the question is unfit for this site.
I was wondering how secure th... |
I'd like to show a CAPTCHA to prevent brute forcing attempts, but I was thinking of showing it whenever a user fails for an invalid username/password combination after X attempts, regardless of whether that user exists in the database or not.
The thought was that if a user did exist, then all an attacker would have to ... |
I want to develop a system, something like a comment system for a website, that ensures I know who is posting comments. The content that is exchanged is not valuable and does not need to be encrypted, I just want to have a some reasonable assurance that the person posting the comment is in fact who they say they are. I... |
I wrote a simple system with SP-initiating Web SSO scenario based on OIOSAML. To test the system, I deployed it on the remote host. However AssertionConsumerServiceURL, where I specified URL, on which Shibboleth idP (idP based on Shibboleth) should return the answer is not called.
SAMLAssertionConsumer - just a simple ... |
My antivirus picked up an infection by Dialer/Coulomb. The definition of a dialer is a piece of malware that dials a number that charges money. How would it do this, is this from when modems were connected to the phone lines? Can this still happen if the computer is connected through wi-fi to a cable modem?
|
I am able to inject this:
http://domain.com/search/songs/<img src='alert(document.cookie)' onerror='alert(document.cookie)'>
to the page HTML.
The onerror event is giving me the cookie on my latest updated Firefox.
But Chrome is sanitizing the HTML to this:
<img src="alert(document.cookie)" onerror="">
When I try to... |
When you find a vulnerability, do you contact CVE assigners before contacting the vendor or after the vendor has fixed the problem?
PS: do not link to How are CVE identifiers assigned and managed?, as it doesn't answer my question.
|
Is it possible to implement MITM attack on larger networks than LAN? For example is is possible to implement such an attack on the whole network of an ISP?
|
I want to make sure each of my apps users only get their own data, and that nobody tampers with it or sniffs it in a MITM fashion. Encryption of everything should be the solution, right? But how do I distribute the keys?
Afaik SSL/TLS only makes sure the client is talking to the correct server, not the other way aroun... |
I've read that the answer has something to do Socialist Millionaire, but I still don't understand how can the user be protected against malicious Man In The Middle, which would capture the question and answer by itself if it knows the answer. Could anyone explain that to me how can we authenticate someone getting his k... |
Can anyone please give me a quick crash course on SSH and GPG?
SSH:
What is the difference between public and private keys?
Should I back up my ~/.ssh/ directory, what are the security implications of doing so?
GPG:
Again, difference between public and private keys.
What is an effective way to use GPG? Encrypt a text ... |
I'm a tired of these stupid scammers trying to rip off fellow university students desperate for housing, so as for some free time activity I thought I'd try and do some scam baiting, and send him to MoneyGram and Western Union a few times in vain for the fun of it :)
I will use a free online gmx account for the email.... |
I have a Debian 7 VPS that runs Nginx, PHP5-FPM and MariaDB. This server runs a couple of WordPress installations, phpMyAdmin and Roundcube Webmail. One is my personal blog running WP 3.9.1 and another runs the latest WP trunk version 4.0-beta1 for development purposes.
I am the only person to have SSH access as well a... |
By default, something like gpg -d file.gpg sends it's output to stdout. What happens to input that is sent to stdout? Is it possible to recover this?
|
I am very familiar with OpenPGP but don't even use X.509 / S/MIME. I know that there are several classes for certificates (from email check to personal ID check). I would like to know how you determine the class of a certificate.
Is this information part of the CA signature? Or is that an organuzational feature only, u... |
For this question, I'm calling an "invisible CA" one that
Is signed by a root ca and exists as a 2nd or 3rd tier
Is valid, not expired or revoked
Has a different Public key than one that is currently dominant and active
This scenario could occur in reality when
A normal subCA (root0-1) gets renewed*
A malicious o... |
If I wanted to crack a password, "cba", but the dictionary I was using only had abc in it, does a dictionary attack try all combinations of abc? abc, acb, bca, bac, cba, cab
Or would cba have to be specified in the dictionary in order to try it?
|
Recently an employee of mine developed a website in WordPress. Things were all fine until we received an email from Google , notifying me that some stuff that can really create security issues is going on in the WordPress site. On checking the FTP, I found an unusual folder there!! I could not delete it or modify it. T... |
Lets say there is an AJAX application where the user can submit items - buy them.
And there was a code
IF ($_POST[items] > 20) {
echo 'error';
}
else {
do_buy($_POST[items]);
echo 'success'
}
Here, there is a check if items is not more than 20. On client side, it should not be possible to choose more than 20... |
With the recent announcement of Touch ID APIs for third party apps, I am wondering how can we leverage this feature to perform secure transaction ? I am looking for a method to use Touch ID in my payment application. One option is to store the password in the keychain and add access policies to invoke Touch ID during p... |
While reading about NOTRACK target of raw table in iptables, I encountered an article suggesting that for certain traffic you could (or even should) disable connection tracking. The two examples were: (1) all kind of routed packets, and (2) if you have a web server, or other services that eat resources, you should also... |
I wish to start with blackberry mobile application penetration testing.
I researched on net but no "in-depth" knowledge is available.
Here is a good article but not much is covered.
http://resources.infosecinstitute.com/security-assessment-of-blackberry-applications/
I had a look at this question BlackBerry handheld ... |
Is there any reversible hash function?
The hash function like SHA and MD5 are not reversible. I would like to know if there exist some reversible hash functions?
|
I am looking forward to learn more on implementing SSL/TLS, can anyone of you suggest me a good source to learn about it?
For now I only have basic knowledge about it such as what is SSL and how it works.
Thanks.
|
I yesterday visited a restaurant I usually visit, but it seems that after paying with my debit card, I accidentally left it there. Today (almost 24 hours later) I had realized that I didn't have it with me anymore.
I am not really that concerned about the unauthorized use of the card, since my previous experience with ... |
In my application, I build REST APIs so that user can interact with my application server.
Since I do not want to maintain User/Passwords, my iOS app authenticates client using Google. This all happens on iOS device
Once client is authenticated, I would give a call to my app server to fetch user's data. The problem... |
Google, Facebook, Twitter, and several other services still knows the older passwords which we used on our accounts. At times, I can not reuse the same password as I have. Then with Google, if I type an old password by mistake, it tells me when I last changed my password. I think this could be more or less of a securit... |
From what I have noticed, there is very few services that offer the Remember Email over Remember Me or Sign-in Automatically.
These options really do make the life easier for the end-user of applications. I strongly think that Remember Email would be way better with making the user input their password into the passwor... |
I ordered a Nokia phone online and it turned out that the packet had been tampered and the phone was missing from the package. Obviously it does not have a SIM card, etc.
I assume someone stole it and is using the phone with a new SIM card. Is there any way that the phone can be tracked ?
|
I am connected to my router and I want to know if it is a possibility to sniff a data from a router that is over my router?
|
The possibility to enable port forwards for any hosts inside the LAN has of course security implications. The problem from my point of view is not that there are bad users, but bad hosts/programs and of course the problem of CSRF.
But for some applications it would be good to have such a thing. Other possibilities lik... |
I have a scenario where I want to encrypt the file data on client machine along with smart card authentication. I have followed a link that states that for smart cards, private key never leaves The card. It further explains that File data encryption should be done using on-board smart card processor with the session ke... |
How to find encryption method if both encrypted and decrypted code known?
j1RSfCKUuvqjHLBtuIe9AOb03gkd2ENLj+KNkWUHff6duf1/iz2zNjU48B0v4O3PFWV3Q0scOPYDu7vuW2mvNKJWXQrIpHGCBEeqyXpihR1WWQo6hfe81YenVH35Gxp/7Xmltp5V8+XEhXOV8jyXtjBaKGVNgmA6F5kmQPAqCaA=
this is a sample encrypted code, how could i identify its method if i... |
The Story:
Yesterday at 12pm a neighbor of mine was pulling into his driveway, and saw that his van's back-window was shattered. Well, this neighbor and I have had some trouble with each other in the past (only noise complaints though) because he is in a band, and plays in his garage; however, it was not me who broke t... |
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 is_responsive = false;
var use_keywords = false;
Date.prototype.addHours = function (h) {
this.setHours(th... |
I get the OS type of a remote host by:
connecting to an open port (telnet <host> 22);
using Nmap (nmap -A <host>).
What are techniques and how to hide or change the information about OS? I would like to get answers with respect to GNU/Linux or (and) BSD OS.
|
Lets say there is AJAX application where user can submit items - buy them.
And there was a code
IF ($_POST[items] > 20) {
echo 'error';
}
else {
do_buy($_POST[items]);
echo 'success'
}
So there is a check if items is not more than 20, lets say on client side it is not possible to choose more than 20 items, b... |
I have a client that generates a csr, sends it to a server, the server then sign it and return the certificate as a String.
the String is then decoded to a x509Certificate (using Bouncycastle's PEMParser) which is then imported to the client keystore.
The questions are:
Should i verify/validate anything before importi... |
I'm testing a system which involves updating a database using files sent from external parties. These files sent from external parties are basically just large flat files to update a database. The requirement is that these files must be signed used a File Signing Key in accordance with the FIPS 186-4 Digital Signature ... |
Considering the recent thread regarding anti-virus for the Mac I wonder how many of the arguments put forth are relevant today to Linux systems, specifically Ubuntu.
There are no known Ubuntu desktop malware in the wild.
GNU/Linux is a very tempting target for botnets, considering that powers a substansial fraction of... |
This is my first question here in Information Security SE. Is there a recommendation to help telling the scenarios where authentication should precede authorization from the ones where authorization comes first?
I experienced both situations at different workplaces (the situation was very similar, switching to a system... |
If a user wants to login to a system/server, it's recommended to have the hashed&salted password saved in a database, along with its salt.
So the user wants to login, types in the password, clicks on login and with his input and the salt the system checks if the correct hash is created.
I understand this part.
But when... |
A Yahoo! answers user suggested that there are 5^5 possible unique configurations for a physical key, but the answer wasn't sourced. I wondered if anyone had similar numbers for how many possible key combinations there are. I ask because, it seems impossible that there can be a unique key for every lock in the world, a... |
I'm starting a very large project soon. It must include a licensing system.
The project will produced using PHP/Laravel/JavaScript and use many different libraries, a CMS, and a few databases.
The software will be licensed out to other companies, which is why the ability to enable/disable usage is very important.
For ... |
I use LastPass for Android with the PIN option. After having entered my full Lastpass password the first time that I used the app, now when opening the application I have access to all my passwords just by entering a four-digit PIN.
How secure can this be? Where might the data stored such that it is accessible by PIN o... |
I have a web site hosted from my server. Sometimes, I upload database manipulation scripts to a folder which is three levels deep in the website and run them using my web browser. These scripts should not be accessed by outside users and I remove them within hours of uploading them. Is there a risk that these script... |
I know that the following authentication protocol is vulnerable, but I can't understand why.
A and B share a secret key K (64 bits)
R1 and R2 are two 64 bit numbers
A-->B: I am A
B-->A: R1
A-->B: Hash((K+R1) mod 2^64), R2
B-->A: Hash((K+R2) mod 2^63)
My thinking is that the two hashes don't line up, but I don'... |
I have a folder that I don't want to be accessible from outside my network's LAN. It seems like all traffic from the outside world goes through my firewall (192.168.1.39). So I made my .htaccess as follows:
Order Allow,Deny
Allow from all
Deny from 192.168.1.39
My thinking is that it allows all traffic, except for tra... |
One of my clients wants to provide an URL to each of his customers to register in a system. This URL would contain a query string parameter with some data (e.g. code, email and name) from his clients encrypted using AES with CBC, similar to this (IV is in bold):
www.website.com/register?key=44a74fb9fad889496e970c604e54... |
I am a Python / C developer currently working on a extremely important piece of software. The details of the code will not be mentioned, and the only place the code appears is on my own hard drive, in a virtual disk image used by a windows 7 virtual box (a hard drive inside a hard drive I guess). The algorithm represen... |
In movies and TV shows, characters are often depicted using devices and applications that are able to determine an encryption key or passcode character by character (or digit by digit). I am a programmer and think I have a decent idea of how encryption works in general but I'm not sure whether to take this as a simple... |
Having a more-than-elementary knowledge of internet security, I've realized that some web applications and websites I use implement a less-than-ideal password policy. Some examples include:
Implementing a password-length upper-bound (upper-bounds I have seen are 16, 20, and 32)
Requiring the presence of arbitrary char... |
I recently came across an application that more or less does this:
starts from a (supposedly unknown to others) key
generates a random IV
encrypts some smallish (~ 160 bytes) payload with the key and generated IV using AES256 in CBC mode
[>=60% of payload is comprised of two or three ASCII words, chosen from a suppose... |
I could not able to configure burp suite with browsers. If I use manual connection settings in browsers,I could not load any site.Because my company uses proxy.
Following Methods I have tried but fails:
I have set manual proxy as "127.0.0.1:8080" but my browser could not load any site after that proxy change.Though bur... |
Our application is using loadXML extensively to recieve data(input) from the users.
Other than the usual checks for SQL injections and XXS, are there any known risks in parsing the xml file using loadXML?
The XML files are limited in size and will be under 2MB.
Could someone potentially create an XML files with a malic... |
So I was just reading up on the OWASP site about PHP Object Injection. According to their site, the suggested fix is to not use serialze and unserialize but to use
json_encode and json_decode.
However, after doing a few tests in a limited amount of time I have found that this isn't the case at all. For example (workin... |
...its remote administration feature is locked down to a single IP/Range? If so, why?
This has been an ongoing office debate for a while now, I claim that it would be possible as it is likely to be the internal web server and the technologies it uses (cgi etc.) that will handle that remote authentication, but I have m... |
The situation comes down to this:
When I enter in hotmail, it retrieves my messages connecting to other providers: they could only do so by using my email and password.
Since I had signed in a couple of days ago, I do not need to put my email/password again: hotmail doesn't know any secret about me/this specific sessi... |
I was curious on some best practices for securing Outlook against hackers.
The data transmitted between the email server and client are almost always encrypted these days but I haven't seen a great deal of security when the mail actually is on the local machine. If someone were to gain access to your machine rather it ... |
Does having a nonce in CTR mode actually improve security (vs. just using 1, 2, 3, etc. - basically a constant nonce of 0)?
As far as I can tell, the best-case scenario security-wise is that the nonce could act as a sort of second key, which would also be shared securely between the communicating parties. But if the un... |
I'm new to the IT Security Stack Exchange! This is my question: I've Skype installed on my Windows 7 computer. In the last few months I've noticed my mouse cursor blinks (I mean it shows that cursor that appears when the computer is processing something) every time I type or click while Skype is the "focus" of my atten... |
I used encfs to encrypt some important files on my system, but sadly I forget the encryption key. I still have a version of some of the the encrypted files.
Is there there a way to get the encryption key if I have the two versions of the file (the encrypted and decrypted one), so I can use this key the get the rest of ... |
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