ENSRT Incident Note ETS-i-2005-12564

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.BL@mm

Release Date: 04/29/2005
Last Updated:

Print this alert

Overview

W32.Mydoom.BL@mm is a mass-mailing worm that retrieves e-mail addresses from the Windows Address Book on the infected computer and uses the SMTP Protocol to further proliferate. Additionally, this worm attempts to spread through the Kazaa peer-to-peer file sharing network.

Also known as:
Email-Worm.Win32.Mydoom.as [Kaspersky Lab], W32/Mydoom.bn@MM [McAfee], W32/MyDoom-BN [Sophos], WORM_MYDOOM.AQ [Trend Micro]

Details below will describe the characteristics of the W32.Mydoom.BL@mm worm as well as provide detection, containment, and prevention techniques available through Enterasys Secure Networks solutions.

Systems affected

Windows operating systems

Systems not affected

Linux and MAC/OSX

Description

The W32.Mydoom.BL@mm mass mailer arrives in the user's mailbox using a wide array of spoofed sender names, attachment names, and extensions chosen at random from a predefined list. The e-mail subject line will contain one of the following:

- Oi a quanto tempo... =)
- Eu nao ti vejo a muito tempo.
- Duvido voce me reconher =)
- Voce me reconhece??
- Saudades de voce!!!
- lembra de mim??
- estou longe!!
- Eu te amo

The e-mail will include the following body:

- Ola, a quanto tempo! Eu me mudei dai para os Estados Unidos, e faz um tempo que perdemos o contato e consegui seu email atraves de uma amiga sua. Vamos fazer assim, eu vou lhe mandar meu album de fotos se voce me reconhecer, me retorna o email. Quero ver se voce ainda lembra de mim. :)

If the attached executable is launched the PC will become infected and the W32.Mydoom.BL@mm worm will display a notepad file containing a large amount of garbage characters. In addition, the worm drops a copy of itself into the Windows system folder as "TASKMON.EXE" and edits the system registry so that the worm is run at Windows system startup.

The W32.Mydoom.BL@mm worm then gathers e-mail addresses from the Windows Address Book and sends multiple copies of itself to each contact on the list with an embedded SMTP engine.

Finally, W32.Mydoom.BL@mm places a number of copies of itself under false names in the Kazaa share folder. Then the worm opens a backdoor on the infected system so that it can be used as a remote proxy.

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 that detects W32.Mydoom.BL@mm can be retrieved via Dragon Live Update and is located in the Master Library within the ENSRT category. The signature "ENSRT:W32-MYDOOM-BI-001" can be 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, 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

The Enterasys Dynamic Intrusion Response (DIR) solution can be utilized to remove infected end-users from the enterprise network by detecting the infection with a Dragon NIDS signature (see "Detection" section of this report), locating the user's connection point using Automated Security Manager's location services module, and either placing the user in a quarantine VLAN or disabling the associated switch port for the user.

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.bl@mm.html
http://www.trendmicro.com/vinfo/virusencyclo/default5.asp?VName=WORM%5FMYDOOM%2EAQ&VSect=P

This document and the information contained herein are intended solely for informational use. Enterasys Networks, Inc. makes no representations or warranties of any kind, whether expressed or implied, with respect to this information and assumes no responsibility for its accuracy or completeness. Enterasys Networks, Inc. hereby disclaims all liability and warranty for any information contained herein and all the material and information herein exists to be used only on an "as is" basis. More specific information may be available on request. By your review and/or use of the information contained herein, you expressly release Enterasys from any and all liability related in any way to this information.

A copy of the text of this section is an uncontrolled copy, and may lack important information or contain factual errors. All information herein is Copyright ©Enterasys Networks, Inc. All rights reserved. All information above is subject to change without notice.

Revision History:

Version: 1.0

Date: 04/29/2005

Author: ENSRT STAFF

Change

Enterasys - Secure Networks