ENSRT Incident Note ETS-i-2005-12553
The Enterasys Networks Security Response Team (ENSRT) publishes incident notes to provide information for our constituents to raise awareness of issues deemed threatening to the security and integrity of our customers.
Worm - VBS.Ypsan.D@mm
Release Date: 04/11/2005
Last Updated:
Overview
VBS.Ypsan.D@mm is a mass-mailing worm that that spreads by sending itself to e-mail addresses gathered from the Windows Address Book of the computer that it has infected. Its primary functionality is to attempt to shutdown the compromised computer.
Details below will describe the characteristics of the VBS.Ypsan.D@mm as well as provide detection, containment, and prevention techniques available through Enterasys Secure Networks solutions.
Systems affected
Windows operating systemsSystems not affected
Linux and MAC/OSXDescription
The VBS.Ypsan.D@mm worm arrives via an e-mail attachment and displays the following characteristics:
Subject: Back Up System
Message: The information that u asked for, Downloads and install the an Attached file, so you can save backs to your computer. To help you just in case you deleted or uninstalled some that you didn't want uninstall.
Attachment: Install.vbs
Once executed, the VBS.Ypsan.D@mm worm performs several destructive actions.
1) The worm renames itself upon install to avoid detection.
2) The worm attempts to delete several .ini and .exe files including the Regedit.exe file so that it is more difficult to manually remove.
3) The worm adds values to the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run registry key so that the malicious program is invoked upon each startup.
4) The worm adds values to the C:\autoexec.bat file in an attempt to delete or disable antivirus software.
5) The worm sends an e-mail with an attachment of itself to all users in the Windows Address Book.
6) The VBS.Ypsan.D@mm worm's final action is to shut down the infected computer.
Threat Assessment
Mass-mailing worms if not addressed through prudent remediation steps may congest mail servers and/or degrade network performance. Mass-mailing worms may impact individual system performance and compromise security settings allowing unauthorized remote access to the compromised host.
Remediation
| Matrix N7 | X |
| Matrix E7 | X |
| Matrix E6 | X |
| Matrix E5 | X |
| Matrix E1 | X |
| VH | X |
| C-Series | X |
Detection
A specific Dragon signature to detect the VBS.Ypsan.D@mm worm can be retrieved via Dragon Live Update and is located in the Master Library within the ENSRT category. The signature "ENSRT:VBS-YPSAN-D-001" can be copied into a custom library and Deployed on a Dragon network sensor that is protecting the enterprise SMTP server to successfully detect end-user class machines which have become infected with the worm.
NOTE: All signatures in the ENSRT library are disabled by default. These signatures must be enabled after they are imported into a custom library if they are to be successfully deployed.
Prevention
Trusted End System solutions are capable of monitoring various end system activity. TES is able to take immediate action such as firewalling specific IPs, TCP/UDP ports, applications, or placing the user into a Quarantine policy or VLAN until end system threat is mitigated. Learn more at: http://www.enterasys.com/solutions/secure-networks/trusted_end_system/
Containment
Using Enterasys Policy Manager, enforce a policy that allows SMTP traffic from end user PCs to authorized SMTP mail servers and blocks SMTP traffic to unauthorized end users or unknown Internet systems. If the SMTP protocol is not implemented for end users within the enterprise, consider implementing a policy blocking SMTP traffic from end user ports.
Repair
Monitor Dragon Realtime Console for alerts that end-user PCs have become infected with the virus. Once isolated, see your anti-virus vendor for Windows repair procedures for infected users.
References
http://securityresponse.symantec.com/avcenter/venc/data/vbs.ypsan.d@mm.html
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Revision History:
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Version: 1.0 |
Date: 04/11/2005 |
Author: ENSRT STAFF |
Change |