__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN ExploreZip (packed) Worm Addition to CIAC Bulletin J-047 December 1, 1999 17:00 GMT Number K-008 ______________________________________________________________________________ PROBLEM: A variant of the ExploreZip Worm (See CIAC Bulletin J-047) is spreading rapidly. The new variant is a packed version of the original worm and is not detected by existing antivirus programs. The worm spreads by sending itself as an attachment to e-mail. The worm is destructive, zeroing the contents of files and making them unrecoverable. PLATFORM: The worm runs on all Windows platforms but Outlook or Exchange are needed to spread. DAMAGE: The worm zeroes the contents of files making them unrecoverable by any reasonable means. The worm specifically targets .h, .c, .cpp, .asm, .doc, .xls, and .ppt files. SOLUTION: Do not execute an e-mail attachment named zipped_files.exe as this is the worm program. Update your antivirus software as soon as updates are available. ______________________________________________________________________________ VULNERABILITY Risk is high: This worm spreads rapidly using your e-mail ASSESSMENT: program to send itself to everyone in your e-mail inbox. ______________________________________________________________________________ CIAC has information that the ExploreZip (packed) Worm is spreading rapidly. The ExploreZip (packed) Worm is a variant of the ExploreZip worm described in CIAC bulletin J-047. This variant is only different from the original in that it is a packed executable. Packed executables are a form of file compression that is uncompressed on the fly when the program is executed. See the CIAC bulletin J-047 for the details of this worm. The worm spreads as an attachment to an e-mail message that appears to be a reply to a message you have sent. The attachment is named zipped_files.exe and is supposed to be a self extracting archive of documents. When the attachment is run, it checks your e-mail inbox and sends a reply to every message it finds there. In the reply, it adds the text: Hi ! I received your email and I shall send you a reply ASAP. Till then, take a look at the attached zipped docs. bye. and attaches the worm program. After sending the e-mail messages with the attached worm to all your associates, the worm starts zeroing the contents of files with the following file extensions. .h .c. cpp .asm .doc .xls .ppt Because this is a packed version of the original worm, current versions of most antivirus products do not detect it. Updates are already available or are expected momentarily. If you have been infected and need to remove this worm by hand, perform these steps: 1. For Windows 95, 98, open the WIN.INI file and remove the following line: run=C:\windows\system\Explore.exe or run=C:\windows\system\_setup.exe If your windows\system directory is in a different location, then the strings above will also be different. For Windows NT, run REGEDIT and remove the following entry: HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows\Run Value = Explore.exe or _setup.exe 2. Delete the file C:\windows\system\Explore.exe or C:\windows\system\_setup.exe. Again, if your windows\system directory is in a different location, use that path instead of the two listed above. ______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@llnl.gov For emergencies and off-hour assistance, DOE, DOE contractor sites, and the NIH may contact CIAC 24-hours a day. During off hours (5PM - 8AM PST), use one of the following methods to contact CIAC: 1. Call the CIAC voice number 925-422-8193 and leave a message, or 2. Call 888-449-8369 to send a Sky Page to the CIAC duty person or 3. Send e-mail to 4498369@skytel.com, or 4. Call 800-201-9288 for the CIAC Project Leader. Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ (or http://ciac.llnl.gov -- they're the same machine) Anonymous FTP: ftp.ciac.org (or ciac.llnl.gov -- they're the same machine) Modem access: +1 (925) 423-4753 (28.8K baud) +1 (925) 423-3331 (28.8K baud) CIAC has several self-subscribing mailing lists for electronic publications: 1. CIAC-BULLETIN for Advisories, highest priority - time critical information and Bulletins, important computer security information; 2. SPI-ANNOUNCE for official news about Security Profile Inspector (SPI) software updates, new features, distribution and availability; 3. SPI-NOTES, for discussion of problems and solutions regarding the use of SPI products. Our mailing lists are managed by a public domain software package called Majordomo, which ignores E-mail header subject lines. To subscribe (add yourself) to one of our mailing lists, send the following request as the E-mail message body, substituting ciac-bulletin, spi-announce OR spi-notes for list-name: E-mail to ciac-listproc@llnl.gov or majordomo@rumpole.llnl.gov: subscribe list-name e.g., subscribe ciac-bulletin You will receive an acknowledgment E-mail immediately with a confirmation that you will need to mail back to the addresses above, as per the instructions in the E-mail. This is a partial protection to make sure you are really the one who asked to be signed up for the list in question. If you include the word 'help' in the body of an E-mail to the above address, it will also send back an information file on how to subscribe/unsubscribe, get past issues of CIAC bulletins via E-mail, etc. PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC) J-070: Microsoft Windows 95 and 98 Telnet Client Vulnerability J-071: Buffer Overflow Vulnerability in amd J-072: IBM AIX Buffer Overflow Vulnerability K-001: Four Vulnerabilities in the Common Desktop Environment K-002: Microsoft IE 5 Vulnerability - "download behavior" K-003: Windows NT 4.0 does not delete Unattended Installation File K-004: Microsoft "Excel SYLK" Vulnerability K-005: Microsoft "Virtual Machine Verifier" Vulnerability K-006: Microsoft - Improve TCP Initial Sequence Number Randomness K-007: Multiple Vulnerabilities in BIND