ENSRT Incident Note ETS-i-2005-12565
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.Banish.A@mm
Release Date: 05/02/2005
Last Updated:
Overview
The W32.Banish.A@mm worm is a mass-mailer and also spreads through the network by exploiting the Microsoft Windows LSASS Buffer Overrun Vulnerability .
Also known as: W32/Banish-A [Sophos], WORM_BANISH.A [Trend Micro]
Details below will describe the characteristics of the W32.Banish.A@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.Banish.A@mm mass mailer arrives in the user's mailbox from a previously pilfered random contact. The e-mail subject line will contain one of the following messages:
- OK. Read the attached instructions to solve the problem.
- Here are the details.
- Re: Thank you for your choice.
- Thank you for shopping. This mail contains your invoice.
- Thank you. Your credit card was processed successfully.
The body of the W32.Banish.A@mm e-mail is blank.
If the attached executable is launched, the PC will become infected and the W32.Banish.A@mm worm will copy itself into the Windows installation folder. In addition, the worm alters the system registry entries and adds entries so that it is run at each Windows system startup. The W32.Banish.A@mm worm then gathers e-mail addresses by submitting queries to popular search engines and then forwards worm copies to any contacts that are gathered.
The worm will then scan for vulnerable computers and try to exploit the Microsoft Windows LSASS Buffer Overrun Vulnerability. It also will attempt to log network traffic in an attempt to steal passwords and delete all files in the Windows repair directory.
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
Specific Dragon signatures that detect the W32.Banish.A@mm worm can be retrieved via Dragon Live Update and are located in the Master Library within the ENSRT category. The five individual signatures with the prefix "ENSRT:W32-BANISH-A" 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 that contains all of the signatures within the "ENSRT:W32-BANISH-A" 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%5FBANISH%2EA&VSect=P
http://securityresponse.symantec.com/avcenter/venc/data/w32.banish.a@mm.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: 05/02/2005 |
Author: ENSRT STAFF |
Change |