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My computer keeps infecting USB pen drives


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#1 W.P.B.

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Posted 11 August 2009 - 03:27 AM

Hello,

I am running Windows XP Home edition, and I have AVG Free installed and updated daily.

I observed some strange behaviour in my PC several weeks ago - Windows Security Center was claiming AVG was turned off when it wasn't (it's still doing this now). Searching around on the Internet, I found out that this could be being caused by a virus, so I ran a full scan, but that turned up nothing. Not trusting AVG's results, I then installed some other anti-malware products, like a-squared Free and malwarebytes among others, but their scans all produced very different results, and I didn't know whether I could trust any of them!

Something had disabled CTRL-ALT-DEL, which I reinstated with a registry mod., and something had been messing with my Hosts file, attempting to stop me visiting certain websites for spyware removal, so I wiped the file completely.

Anyway, I recently discovered that USB pen drives weren't working in my machine. When I plugged them in, I got a folder icon in My Computer, rather than the usual removable drive icon, and double-clicking on that didn't open the pen drive. Fortunately, I have access to another operating system (RISC OS), and using that I was able to see that an autorun.inf file was being placed on my pen drives which referenced a 'recycler' folder that was also being put on the pen drives, inside which were a few things including an executable called 'recycld.exe'.

I can remove these files on RISC OS, and then use the pen drives in other machines without any problems.

But if I plug them into my computer, they get infected again.

I intend to reinstall my machine from scratch, because I think I'm riddled with nasties, but I was hoping to at least get to the bottom of what's causing this pen drive problem first, to help others and help myself if it ever crops up again.

Would anyone be willing to help?

Thanks,

Will

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#2 quietman7

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Posted 11 August 2009 - 09:00 AM

I was hoping to at least get to the bottom of what's causing this pen drive problem first, to help others and help myself if it ever crops up again.

Flash (usb, pen, thumb, jump) drive infections usually involve malware that modifies and loads an autorun.inf (text-based configuration) file into the root folder of all drives (internal, external, removable) along with a malicious executable. When removable media such as a CD/DVD is inserted (mounted), autorun looks for autorun.inf and automatically executes the malicious file to run silently on your computer. For flash drives and other USB storage, autorun.ini uses the Windows Explorer's right-click context menu so that the standard "Open" or "Explore" command starts the file. Malware modifies the context menu (adds a new default command) and redirects to executing the malicious file if the "Open" command is used or double-clicking on the drive icon. When a flash drive becomes infected, the Trojan will infect a system when the removable media is inserted if autorun has not been disabled.

Keeping Autorun enabled on USB and other removable drives has become a significant security risk due to the increasing number of malware variants that can infect them and transfer the infection to your computer. To learn more about this risk, please read:You can hold down the Shift key when inserting the drive into your computer until Windows detects it to keep autorun.inf from executing automatically. However, many security experts recommend you disable Autorun asap as a method of prevention. Microsoft recommends doing the same.

...Disabling Autorun functionality can help protect customers from attack vectors that involve the execution of arbitrary code by Autorun when inserting a CD-ROM device, USB device, network shares, or other media containing a file system with an Autorun.inf file...

Microsoft Security Advisory (967940): Update for Windows Autorun

An easy way to disable Autorun on a specific drive is to download and use Microsoft Power Toy Tweak UI and then follow these instructions

Note: When Autorun is disabled, double-clicking a drive which has autorun.inf in its root directory may still activate Autorun so be careful. Disabling autorun/autoplay does not prevent you from accessing your media sources. They are still available by opening My Computer and accessing the source drive (CD, DVD, USB or external hard drive). Pictures on a camera can still be accessed through My Pictures and selecting "Get Pictures" from a scanner or camera. Media can be accessed via the program you normally use it with such as music CDs via Media Player, blank CDs via burning software, image handling software provided with the camera. I strongly recommend you leave the autorun feature disabled and get into the habit of accessing your media devices manually.

If using Windows XP Pro you can also use the Group Policy Editor (gpedit.msc) to disable the autorun for USB & CD-ROM devices. To do this, please refer to:If using Windows Vista, please refer to:Note: For steps that require registry changes, always back up your registry before making any changes

However, disabling AutoRun is not enough. See Scott Dunn's One quick trick prevents AutoRun attacks. For most novice users, the easiest way to inoculate a USB Flash Drive is to create a Read-only folder on the drive named autorun.inf and place a small file inside or just use Flash_Disinfector which does the same thing for you. Flash_Disinfector is a specialized fix tool created by sUBs to remove infections that load an autorun.inf file on removable media. As part of its routine, this tool will create a hidden folder named autorun.inf in each partition and every USB drive that was plugged in when you run it. Do not delete this folder...it will help protect your drives from future infection by keeping the autorun file from being installed on the root drive and running other malicious files.

Alternatively, you can download and use Panda USB Vaccine. Computer Vaccination will prevent any AutoRun file from running, regardless of whether the removable device is infected or not. USB Vaccination disables the autorun file so it cannot be read, modified or replaced by malicious code. The Panda Resarch Blog advises that once USB drives have been vaccinated, they cannot be reversed except with a format. If you do this, be sure to back up your data files first or they will be lost during the formatting process.

Finally, always scan USB Flash Drives after they have been used in other computer systems, even your own. An easy way to do this is to download "ClamWin Portable Antivirus", put it on your USB Flash Drive, update its definition files and perform a scan.
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#3 W.P.B.

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Posted 11 August 2009 - 09:30 AM

Thanks for all this detailed information. I've come to see how dangerous autorun can be.

Do you have any advice about how to remove whatever it is on my computer that is putting (or trying to put) the files on the removable media?

A scan with Avira AntiVir shows a problem with 'locsock32.dll' - could that be related to this?

Thanks,

Will

#4 quietman7

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Posted 11 August 2009 - 09:55 AM

ThreatExpert's awareness of the file "locsock32.dll"

Please download and scan with Dr.Web CureIt - alternate download link.
Follow these instructions for performing a scan in "safe mode".
If you cannot boot into safe mode or complete a scan, then try doing it in normal mode. Be aware, this scan could take a long time to complete.
-- Post the log in your next reply. If you can't find the log, try to write down what was detected/removed before exiting Dr.WebCureIt so you can provide that information.

Please download Malwarebytes Anti-Malware (v1.40) and save it to your desktop.
alternate download link 1
alternate download link 2

MBAM may "make changes to your registry" as part of its disinfection routine. If using other security programs that detect registry changes (ie Spybot's Teatimer), they may interfere or alert you. Temporarily disable such programs or permit them to allow the changes.
  • Make sure you are connected to the Internet.
  • Double-click on mbam-setup.exe to install the application.
  • When the installation begins, follow the prompts and do not make any changes to default settings.
  • When installation has finished, make sure you leave both of these checked:
    • Update Malwarebytes' Anti-Malware
    • Launch Malwarebytes' Anti-Malware
  • Then click Finish.
MBAM will automatically start and you will be asked to update the program before performing a scan.
  • If an update is found, the program will automatically update itself. Press the OK button to close that box and continue.
  • If you encounter any problems while downloading the definition updates, manually download them from here and just double-click on mbam-rules.exe to install.
On the Scanner tab:
  • Make sure the "Perform Quick Scan" option is selected.
  • Then click on the Scan button.
  • If asked to select the drives to scan, leave all the drives selected and click on the Start Scan button.
  • The scan will begin and "Scan in progress" will show at the top. It may take some time to complete so please be patient.
  • When the scan is finished, a message box will say "The scan completed successfully. Click 'Show Results' to display all objects found".
  • Click OK to close the message box and continue with the removal process.
Back at the main Scanner screen:
  • Click on the Show Results button to see a list of any malware that was found.
  • Make sure that everything is checked, and click Remove Selected.
  • When removal is completed, a log report will open in Notepad.
  • The log is automatically saved and can be viewed by clicking the Logs tab in MBAM.
  • Copy and paste the contents of that report in your next reply. Be sure to post the complete log to include the top portion which shows MBAM's database version and your operating system.
  • Exit MBAM when done.
Note: If MBAM encounters a file that is difficult to remove, you will be asked to reboot your computer so MBAM can proceed with the disinfection process. If asked to restart the computer, please do so immediately. Failure to reboot normally (not into safe mode) will prevent MBAM from removing all the malware.

-- If Malwarebytes Anti-Malware results in any error messages, please refer to Fixes for common problems and Error Codes. Some issues with errors can be related to malware infection but others are not.

-- Some types of malware will disable Malwarebytes Anti-Malware and other security tools. If MBAM will not install, try renaming it first.
  • Right-click on the mbam-setup.exe file file and rename it to mysetup.exe.
  • Double-click on mysetup.exe to start the installation.
  • If that did not work, then try renaming and changing the file extension. <- click this link if you do not see the file extension
  • Right-click on the mbam-setup.exe file, rename it to mysetup and change the .exe extension to .scr, .com, .pif, or .bat.
  • Then double-click on mysetup.scr (or whatever extension you renamed it) to begin installation.
If after installation, MBAM will not run, open the Malwarebytes' Anti-Malware folder in Program Files.
  • Right-click on mbam.exe, rename it to myscan.exe.
  • Double-click on myscan.exe to launch the program.
  • If that did not work, then try renaming and change the .exe extension in the same way as noted above.
  • Double-click on myscan.scr (or whatever extension you renamed it) to launch the program.
If using Windows Vista, refer to How to Change a File Extension in Windows Vista.
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