INFORMATION BULLETIN
INFORMATION BULLETIN
PROBLEM: A trojan program is being distributed around America
Online and other networks called AOLGOLD.ZIP.
PLATFORM: DOS-based PCs
DAMAGE: When the INSTALL.EXE program is executed, most files on
users C: drive are deleted.
SOLUTION: See the descriptions below
VULNERABILITY Users who download the AOLGOLD.ZIP or INSTALL.EXE trojaned
ASSESSMENT: programs, and who unpack, and execute them may destroy
files on their DOS C: drive.
The AOLGOLD Trojan program was recently discovered on America Online (AOL). Notice about the Trojan has been circulated to all America Online subscribers. Notice about the Trojan and a copy of the Trojan program were supplied to CIAC by Doug Bigelow, who is on the staff of America Online.
Apparently, an e-mail message is being circulated that contains an attached archive file named AOLGOLD.ZIP. A README file that is in the archive describes it as a new and improved interface for the AOL online service. Note that there is no such program as AOLGOLD. Also, simply reading an e-mail message or even downloading an included file will not do damage to your machine. You must execute (or run) the downloaded file to release the Trojan and have it cause damage.
If you unzip the archive, you get two files: INSTALL.EXE and README.TXT. The README.TXT file again describes AOLGOLD as a new and improved interface to the AOL online service. The INSTALL.EXE program is a self-extracting ZIP archive. When you run the install program, it extracts 18 files onto your hard drive:
MACROS.DRV VIDEO.DRV INSTALL.BAT ADRIVE.RPT SUSPEND.DRV ANNOY.COM MACRO.COM SP-NET.COM SP-WIN.COM MEMBRINF.COM DEVICE.COM TEXTMAP.COM HOST.COM REP.COM EMS2EXT.SYS EMS.COM EMS.SYS README.TXTThis file list includes another README.TXT file. If you examine the new README.TXT file, it starts out with "Ever wanted the Powers of a Guide" and continues with some crude language. The README.TXT file indicates that the included program is a guide program that can be used to kick other people off of AOL.
If you stop at this point and do nothing but examine the unzipped files with the TYPE command, your machine will not be damaged. The following three files contain the Trojan program:
MACROS.DRV VIDEO.DRV INSTALL.BAT
The rest of the files included in the archive appear to have been grabbed at random to simply fill up the archive and make it look official.
The Trojan program is started by running the INSTALL.BAT file. The INSTALL.BAT file is a simple batch file that renames the VIDEO.DRV file to VIRUS.BAT and then runs it. VIDEO.DRV is an amateurish DOS batch file that starts deleting the contents of several critical directories on your C: drive, including:
c:\ c:\dos c:\windows c:\windows\system c:\qemm c:\stacker c:\nortonIt also deletes the contents of several other directories, including those for several online services and games, such as:
c:\aol20 c:\prodigy c:\aol25 c:\mmp169 c:\cserve c:\doom c:\wolf3dWhen the batch file completes, it prints a crude message on the screen and attempts to run a program named DoomDay.EXE. Bugs in the batch file prevent the DOOMDAY.EXE program from running. Other bugs in the file cause it to delete itself if it is run from any drive but the C: drive. The programming style and bugs in the batch file indicates that the Trojan writer appears to have little programming experience.
**WARNING** Do not copy any files onto your hard disk before trying to recover your hard drive.
The files are deleted with the DOS del command, and can be recovered with the DOS undelete command. The files are still on your disk, only the directory entries have been removed. If you copy any new files onto your hard disk, they will likely be written over the deleted files, making it impossible to recover the deleted files.
If you have delete protection installed on your system, recovery will be relatively easy. If not, the DOS undelete command can be used, but you will have to supply the first letter of each file name as it is recovered. In many cases, you will probably want to restore the directories by reinstalling them from the original installation disks, but do that last. You must recover any unreplaceable files first using undelete and then replace any others by copying or reinstalling them from the distribution disks.
To recover the system:
1. Boot the system with a clean, locked floppy containing the recovery program for the recovery files you have installed, or the DOS UNDELETE.EXE program if you do not have recovery files installed.
2. Type the VIRUS.BAT file to get a list of the directories the Trojan tried to delete. Ignore any directories that don't exist on your machine.
3. Run the recovery program and recover your files. You may have to help it find the recovery files, such as MIRROR, which will be in the root directory. You may have to recover the MIRROR file first and then use it to recover the other files.
If you are using only the DOS undelete command, type: undelete directory where directory is the name of the directory to examine. To undelete the files in the dos directory, use: undelete c:\dosThe undelete program will present you with a list of deleted files with the first letter replaced with a question mark. Without delete protection, you will have to supply this letter in order to undelete the file.
4. After you have restored as many files as you want or can using the UNDELETE command, replace any others by reinstalling them using the original installation disks.
The Operations staff at America Online has released the following bulletin to their users:
--BEGIN MESSAGE-- Dear Member: As you know, we strive to keep you informed on various issues regarding online safety. We want to take this opportunity to remind you about potential computer viruses and Trojan horses and how to protect your computer. First, a virus is a program that is designed to spread and usually attaches itself to a program with the goal of spreading to other computers. A Trojan horse is a program that is intended to corrupt your computer but has to be activated before it can be executed. For example, a Trojan horse can be distributed as an attached file to an email but the file has to be downloaded and executed before harm is done. If you receive email from unknown senders with an attached file, it is a good rule of thumb not to download the files. In addition, if you ever receive a file in email you believe could cause problems, please forward it immediately to TOSEMAIL1, and explain your concerns to our Terms of Service staff. We have received recent inquiries regarding a Trojan horse that is sent as an attached file in an email message entitled "AOLGOLD" and "Install.exe". It is important to understand that no virus or Trojan horse can be passed along by simply reading email. However, we strongly urge that if you receive email with an attached file with this name not to download it. Due to the private nature of electronic mail, we cannot scan files in email for viruses as we do with files in public areas of the service. We have never had an occurrence of a virus or Trojan horse being spread through simply reading email. In order for one to spread to your computer, you would have to proactively select the attached file and download it to your hard drive. It is therefore advisable never to download attached files from an unknown sender. AOL incorporates virus protection throughout the service and scans all posted software, text, and sound files in public areas. We also offer our members the Virus Information Center on AOL where you'll find information about the latest virus or Trojan horse, along with updates to all the popular commercial, shareware, and freeware anti-virus tools. Keyword: VIRUS. Thank you for taking an active role in maintaining a safe online environment. Sincerely, AOL Operations Staff --END MESSAGE--
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