ENSRT Incident Note ETS-i-2005-12543
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 - W32.Mydoom.BG@mm
Release Date: 03/21/2005
Last Updated:
Overview
W32.Mydoom.BG@mm is a mass-mailing worm that retrieves e-mail addresses from the Windows Address Book on the infected computer and uses an embedded SMTP engine to further proliferate the worm.
Details below will describe the characteristics of the W32.Mydoom.BG@mm worm 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 W32.Mydoom.BG@mm mass mailer arrives in the user mailbox as an e-mail with the subject line "Virus Alert id:" followed by a random 5 digit number.
The message body of the e-mail is composed of a message where the worm poses as a Symantec virus notification with a hyperlink to a "virus removal" program. Through this deception, the worm attempts to convince the end-user to click on the embedded hyperlink and download the file. If the downloaded file is executed, the end-user's computer will become infected with the worm.
Once infected, the W32.Mydoom.BG@mm worm will make changes to the system registry so that the worm will run when the Windows system starts.
Finally, the W32.Mydoom.BG@mm worm gathers e-mail addresses from multiple locations on the host system including the Windows Address Book. With the addresses collected, the embedded SMTP engine then proliferates the worm with the aid of the local SMTP server.
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 W32.Mydoom.BG@mm worm can be retrieved via Dragon Live Update and is located in the Master Library within the ENSRT category. This individual signature, "ENSRT:W32-MYDOOM-BG-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.
If utilizing Dynamic Intrusion Response (DIR), a Dragon Alarmtool policy that consists of an event group containing the signature "ENSRT:W32-MYDOOM-BG" should be used. A threshold parameter of at least three signature detections within a time span of 60 seconds should be used to mitigate the existence of false positives.
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. If utilizing the DIR solution, users can either be expunged from the network or placed in a quarantine VLAN. Once isolated, see your anti-virus vendor for Windows repair procedures for infected users.
References
http://securityresponse.symantec.com/avcenter/venc/data/w32.mydoom.bg@mm.html
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Revision History:
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Version: 1.0 |
Date: 03/21/2005 |
Author: ENSRT STAFF |
Change |