ENSRT Incident Note ETS-i-2005-12536
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.Beagle.BK@mm
Release Date: 03/07/2005
Last Updated:
Overview
The W32.Beagle.BK@mm worm is an SMTP mass-mailing worm deeply integrated with the trojan Trojan.Tooso.E. The malware combination makes use of SMTP mass-mailing techniques, downloading additional components via HTTP, as well as installing a backdoor listener on TCP port 80.
Details below will describe the characteristics of W32.Beagle.BK@mm and Trojan.Tooso.E 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
Trojan.Tooso.E arrives in the user's mailbox via an e-mail and embedded in the rar file attachment. The characteristics of the worm-ridden e-mail follow below. The subject of the e-mail is blank while the message body contains one of the two following messages:
- The password is
- Password:
The rar file attachment is named one of the following:
- 54543.rar
- 075466.rar
- 543.rar
- 34544.rar
- 345556.rar
- 2332134.rar
- 655454.rar
- 977888.rar
If executed, the trojan attempts to download the mass mailing component, W32.Beagle.BK@mm, from one of dozens of potential WEB urls. The mass-mailing component is initially downloaded as a "jpg" file with the name "zo2.jpg".
If the mass-mailing component is successfully downloaded, e-mail addresses are collected from a php file that the worm downloads from the following sites:
- lonestartruckequipment.com
- kienzerhof.at
- humancentrictech.com
- www.gaialogic.com
- kienzerhof.at
Lastly, the W32.Beagle.BK@mm opens a backdoor component with a WEB server listening on TCP port 80. This allows the worm to use the system as a email relay.
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.
Trojans or backdoor listeners if not addressed through prudent remediation steps, can compromise network and host security. Additionally, trojans and backdoor listeners potentially allow theft of information, unauthorized remote access, and damage to critical files.
Remediation
| Matrix N7 | X |
| Matrix E7 | X |
| Matrix E6 | X |
| Matrix E5 | X |
| Matrix E1 | X |
| VH | X |
| C-Series | X |
Detection
The ENSRT signature for the worm variant "WORM_BAGLE.BE" will also detect W32.Beagle.BK@mm. This signature, "ENSRT:WORM-BAGLE-BE-001", can be retrieved via Dragon Live Update and is located in the Master Library within the ENSRT category. Copying this signature to a Dragon custom library and deploying it on a network sensor protecting Internet connections will detect the WEB based downloading of the W32.Beagle.BK components.
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
Internet or edge facing firewalls should be configured with a default 'Deny' policy and contain 'Permit' policies for only needed services and applications. Furthermore, careful inspection of firewall policies that allow TCP traffic streams to be initiated from the Internet into internal enterprise resources is required. These policies should only allow specific protocols to trusted servers thereby combating the increased use of random TCP ports by Internet trojans and worms. In the case of the W32.Beagle.BK@mm worm, careful attention should be paid to assure that firewall policies allow only HTTP traffic initiated from the Internet into enterprise WEB servers and not end-users.
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.
Apply the below available NetSight PMD file and apply the policy to user ports to block the W32.Beagle.BK@mm worm's backdoor listener on TCP port 80.
This NetSight PMD file can be downloaded from here: http://www.enterasys.com/support/pmd.html?12533
Note: This PMD file was originally created for the "WORM_BAGLE.BE" variant.
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.
Scan all clients and servers for newly opened TCP ports that did not appear in previous TCP scans. If viruses are detected apply appropriate removal tools on each client and server that have the open ports (See your anti-virus solution for removal instructions).
References
http://securityresponse.symantec.com/avcenter/venc/data/w32.beagle.bk@mm.html
http://securityresponse.symantec.com/avcenter/venc/data/trojan.tooso.e.html
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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: 03/07/2005 |
Author: ENSRT STAFF |
Change |