Wanted to share some pretty cool sites that have helped me with reverse engineering. If anyone is remotely interested in these topics I highly recommend them.

• Lena’s Tutorials
  These tutorials are fantastic and cover a great range of reverse engineering. Starting from really basic cracks to more advance versions. There are over 20 different tutorials. Highly recommended.
• CrackMes.de
  Repository of files that are made to be cracked. Varying in difficulty for all to try no matter what your level is.
• HackThisSite.org
  Really cool site that gives some basic tutorials on XSS and other web site hacks.

These sites have helped me, hopefully they will be a good resource for others. Happy reverse engineering!

The other day, I was looking for a free weather forecast api for a project I’m working on. I managed to find a few, but the one that seemed to be the fastest and easiest to implement was  ”The secret Google Weather API” (that’s the way it was called in few posts I’ve read).

Anyhow, the “Free Computer Advice” blog, had a nice post that explained how to use this weather API with PHP, but since the site went down on Dec 2011 it’s not accessible anymore.
Luckily, I managed to snag the post’s content from Google Cache before it was removed entirely, so here it is for your pleasure.

So just before pulling out my hacking kit, I decided to give good’ol Google a shot and see if someone has already done the “dirty” work for me… and I’m happy to let you know that someone did (actually it was a bunch of guys) – 4 cool guys from WinMatrix forum (Pinobigbird, untermensch, cocoa & Shipit).

So just before I’ll continue to the howto, I’ll give a short background explanation on why do we need this patch anyway:
Windows 7 has a built in remote desktop (RDP) feature that is limited by default to one concurrent user per session. Which means, that if two users are trying to connect the same machine at the same time, they can’t (actually they can, but the last user who logs in will kick out the user who is already logged in). So what I present here is a solution to allow multiple users with different or similar accounts to simoultaniously login to a windows 7 machine via RDP, by using a patched version of termsrv.dll.

So back to the cool patch by the WinMatrix guys… well, they’ve created a very nice package to contains the following files:
install.cmd – this is the script you’ll have to run
32_termsrv.dll – a patched version of termsrv.dll for x86
64_termsrv.dll – a patched version of termsrv.dll for x64

In order to use it, you’ll have to extract the files to a new folder and execute with administrator privileges (run as administrator).
When you run the install.cmd, you can use the following switches (remove the quotes):
“help” – quick help
“multi Enable” – enable multiple remote desktop sessions per user
“blank Enable” – enable remote logon for accounts which are not password protected

To download the package, click here

I found another patch by TCP-Z, that suppose to be better and support all Windows versions. However, since some users reported problems with this new patch, I’ve decided to keep the link to the old patch if someone needs it.
You can download the new patch from here: UniversalTermsrvPatch_20090425_by_TCP-Z.zip

Just for the reference, here’s a transcript of their hex magic:

x86 Hex edit

find:
00 3B 86 20 03 00 00 0F ** ** ** **
replace:
00 B8 00 01 00 00 90 89 86 20 03 00

find:
FF 43 50 C7
replace:
FF 90 50 C7

find:
F8 74 2F 68 ** **
replace:
F8 E9 2C 00 00 00

x64 Hex edit

find:
8B 87 38 06 00 00 39 87 ** ** ** ** ** ** ** ** ** **
replace:
B8 00 01 00 00 90 89 87 38 06 00 00 90 90 90 90 90 90

find:
60 BB 01 00 00 00
replace:
60 BB 00 00 00 00

find:
50 00 74 18 48 8D
replace:
50 00 EB 18 48 8D

Back then I was coding in ASP3, so I decided to write my own class to do the job, and I named it “Captchavator”.

I’ve planned to release it to the public… but never did (I just forgot about it).

Last night, while I was browsing my HDD, I stumbled upon the Captchavator folder and the decided it’s time to make a move

You might say that ASP 3 is obsolete… and I’ll say “true, true…”, but since there are still many old sites out there, I think that even even if one person will find this useful, then it was worth releasing…

So what’s so special about this solution?

• It requires your web-server to support ASP 3, Javascript and nothing more
• Does not require installing any com/activex object on the server
• Does not require storing images on the server
• Developers can generate their own captcha characters using the included “painter” tool
• Does not use any database to operate
• Can be used with any shared hosting IIS web server

How can you use it?

The process is very simple and involves 4 simple steps…

Step 1 – Include the captcha class in your ASP page.

Step 2 – Create an instance of the Captchavatorobject

Set objCaptcha = New Captchavator

Step 3 – Generate a new captcha (pass the length of the requested captcha, in the following example, I’ve asked for a 6 chars long captcha).

objCaptcha.CreateCaptcha(6)

Step 4 – Print the captcha

objCaptcha.Print()

To validate the captcha, following these steps:

Step 1 – Include the captcha class in your ASP page.

Step 2 – Create an instance of the Captchavatorobject

Set objCaptcha = New Captchavator

Step 3 – Check if the passed POST/GET parameter matches the captcha

objCaptcha.Validate( Request(“txt1″) ) ‘will return true if validated successfully!

What’s included in the archive?

captcha.asp - This is the main Captchavator class

captcha_painter.asp - Use this file to generate your own captcha characters. Please note the painter only works with Internet Explorer (I’m too lazy to fix it to work with FF).

demo.asp - Demonstration of the complete process

I sure hope you’ll find this useful….

Try an online demo:  http://www.isralet.com/files/captcha/demo.asp

Download the Captchavator archive from here:

http://www.isralet.com/files/Captchavator_v1.2-ASP_3_Captcha.rar

Feel free to ask any questions by leaving a comment below.

Lately I’ve been doing some reading on online backups (aka. off-site backup) and it got me thinking…

Everybody knows the importance of backups, but every few weeks or so, I’m still getting this call from another poor soul that usually sounds like this: “oh no, my HDD just died.. what can I do to restore my data?”.

Thing is, most home users fail to backup their data regularly. I must admit that although I consider myself an advanced computer user (who is aware of how important it is to backup your data) I’m still not doing half than I should to make sure my data will be available to me when a catastrophe happens.

So yes, I’ve evolved in the last few years (after losing my laptop HDD and all the data that was on it) and started doing some daily backups between the computers in my home network (copying the data from one computer to another)… so now I feel pretty safe in the occasion of another HDD crash, but I’m still not doing any offline backups.

So what will happen if, god forbids, a burglar will visit me one day and take all my computers with all my precious data? in three words – I am fucked.

Of course the cheapest way to do backups (defiantly not the easiest) is to do it offline – Cassettes/CD’s/DVD’s or what have you. I really don’t know, maybe it’s just me being lazy, but even after losing all the important data I had on my dead laptop HDD I’m still failing to do offline backups and I believe most home users fail to backup their data this way as well.

Which brings me to the point of this email – Online Backup Services

We’ve all heard about them, some of us even experience some of them like xDrive, iBackup and others (I know I have ), but I never liked any of them for few reasons:

Why? few reasons:

1. Speed Speed Speed – if I started a backup session it would take ages until all the data is sent to their servers and it was hogging my bandwidth.
2. Privacy – I’ve never felt I can trust them with my precious data – how can I tell if someone is actually looking at my nude collection?
3. Laziness – I always had to remember to initiate the backup myself. Although most of the services do offer scheduling, it’s pretty worth-less when a backup takes approximately 34 hours

Today I came across another online backup service called Mozy (http://mozy.com/) – which promises unlimited online backup storage for ~55$/year.

To start backing up with Mozy, you need to create an account in their website and then you can download & install their backup software. You set an encryption password, choose the folders you wish to backup and Mozy will do everything else from there.

What I like about Mozy (and what actually differentiate their solution from what I’ve seen so far) is that their software is always running in the background checking which files have changed since the last backup (thus needed to be backed up again) and once your computer is idle, it will send these files to the remote server for backup. pretty neat, uh?

Being a true paranoid and all, I have one problem with Mozy (actually, the same problem applies to all the online backup solutions I know) – How can I be 100% sure nobody from Mozy is browsing my nude photo collection… Now seriously, although they offer a pretty impressive 448-bit Blowfish encryption and send the data over 128bit SSL connection, I still need to trust them not to send my private key to their server along with the data (allowing them to read all my data that is saved on their servers).
So if I was a normal person, I would probably trust them and use their product as is, but since I’m not, I’ve come up with a better solution – combining an external encryption software.

My new backup strategy is about to include another software – an external encryption utility named TrueCrypt (http://www.truecrypt.org/).

TrueCrypt is sort of an “on the fly encryption” utility. You predefine the folders to encrypt and TrueCrypt will create a new encrypted “virtual hard drive” that can be accessed like a normal drive. All the files on the “virtual HDD” will always be encrypted. TrueCrypt will keep encrypting transparently all files that are changing while I’m work with the computer.

To combine TrueCrypt & Mozy together, all I need to do is pointing Mozy’s backup software to the TrueCrypt “virtual hard drive”, and vwalla – I have a top notch secure backup service.

Few points to consider:

• The Mozy service costs ~55$/year (for unlimited backup storage) but you can try it for free (with 2GB of free storage). I myself believe it’s worth spending the 55$.
• Backup with Mozy can take long time (considering the slow upstream connections we have in Israel), but since Mozy is working when the computer is idle I don’t really care.
• I’m aware that are some much more sophisticated backup solutions out there but I was trying to focus on services that are more suitable for home users.
• Please consider, I’ve been using Mozy for only one day and still haven’t tried the combination with TrueCrypt, so before you trust all your precious data with these too, I can only suggest you test it for few days.

Alon