ENSRT Incident Note ETS-i-2005-12548
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 - WORM_MYDOOM.AI
Release Date: 04/01/2005
Last Updated:
Overview
WORM_MYDOOM.AI is a mass-mailing worm that retrieves e-mail addresses from the Windows Address Book on the infected computer and uses SMTP Protocol to further proliferate the worm. Additionally, this worm attempts to spread through the Kazaa peer-to-peer file sharing network.
Details below will describe the characteristics of the WORM_MYDOOM.AI 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 WORM_MYDOOM.AI mass mailer arrives in the user's mailbox masquerading itself as a love letter. The subject line and body of this message are typically misspelled series of phrases, chosen at random from a predefined list. Through social engineering, this worm's messages attempt to coerce the end-user to download and run the attached files and infect the host computer with the worm.
Once infected, WORM_MYDOOM.AI 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 and edits the system registry such that the worm is run at Windows system startup.
The WORM_MYDOOM.AI worm then gathers e-mail addresses from multiple locations on the host system including the Windows Address Book. With the addresses collected, the worm contects the local DNS server to find the local SMTP server, and uses that system to disperse infected emails to the acquired addresses.
Finally, WORM_MYDOOM.AI places a number of copies of itself under false and tempting names in the folder "C:\Program Files\Kazaa\Transfer".
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 set of Dragon signatures to detect WORM_MYDOOM.AI can be retrieved via Dragon Live Update and are located in the Master Library within the ENSRT category. The four individual signatures with the prefix "ENSRT:WORM-MYDOOM-AI" 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.
NOTE: These signatures may not detect every instance of this worm's activity, as some of the detection criteria was deemed too generic and would result in many false positive readings.
If utilizing Dynamic Intrusion Response (DIR), a Dragon Alarmtool policy that consists of an event group that contains all of the signatures within the "ENSRT:WORM-MYDOOM-AI" family 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
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://www.trendmicro.com/vinfo/virusencyclo/default5.asp?VName=WORM%5FMYDOOM%2EAI&VSect=T
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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:
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Version: 1.0 |
Date: 04/01/2005 |
Author: ENSRT STAFF |
Change |