ENSRT Incident Note ETS-i-2005-12585
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.Rants.A@mm
Release Date: 07/11/2005
Last Updated:
Overview
The W32.Rants.A@mm worm propagates by sending e-mail copies of itself with the Microsoft Outlook application. Additionally, the worm makes use of the AOL Instant Messenger application on infected machines to forward messages containing HTTP hyperlinks to a downloadable variant of the W32.Spybot.Worm. Lastly, security is threatened by the termination of system and security related processes on the infected machine.
Details below describe the characteristics of the W32.Rants.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.Rants.A@mm worm arrives via an e-mail with attachment in the user's mailbox using the following Subject line:
- Fwd: Microsoft SP2 Update
Worm W32.Rants.A@mm also contains the following e-mail body:
- Microsoft SP2 Update Download It
Worm W32.Rants.A@mm also an executable attachment with the following name:
- SP2 UPDATE.EXE
If the e-mail attachment is executed, the user's PC becomes infected. The worm performs the following steps:
1) Copies itself to the Windows system directory.
2) Updates the Windows registry to assure the worm starts on system reboot.
3) Updates registry entries to remove security notification alerts regarding the status of the firewall and anti-virus software.
4) Updates the Windows registry to disable Windows Update capabilities.
5) Sends a copy of the worm e-mail to all addresses found in the Windows Address Book via the Microsoft Outlook application.
6) Sends an HTTP hyperlink to all AOL users pointing to a downloadable variant of the W32.Spybot.Worm.
7) Terminates system and security related processes.
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.
AOL Instant Messenger worms if not addressed through prudent remediation steps may impact individual system performance and compromise security settings by 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.Rants.A@mm worm can be retrieved via Dragon Live Update and are located in the Master Library within the ENSRT category.
The signature "ENSRT:W32-RANTS-A-001" detects the worm as it propogates to external mail domains. The worm can be detected as it is sent between the Microsoft Exchange Server and the SMTP server when accessing external mail domains. Deploy this signature on Dragon NIDS devices protecting the pathways to SMTP servers.
The signature "ENSRT:W32-RANTS-A-002" can be copied into a custom library and deployed on Dragon network sensors protecting enterprise Internet connections or end user switch ports. The "ENSRT:W32-RANTS-A-002" signature can successfully detect end-user class machines passing the AOL Instant Message portion of the worm.
If utilizing Dynamic Intrusion Response (DIR), a Dragon Alarmtool policy that consists of an event group that contains the signature "ENSRT:W32-RANTS-A-002" 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.
If the enterprise Acceptable Use Policy (AUP) for end users does not permit AOL Instant Messenger traffic, use Enterasys Policy Manager to implement a policy blocking TCP port 5190 traffic from end user ports to the Internet.
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.rants.a@mm.html
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Revision History:
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Version: 1.0 |
Date: 07/11/2005 |
Author: ENSRT STAFF |
Change |