ENSRT Incident Note ETS-i-2005-12562
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.Allim.A and W32.Allim.B
Release Date: 04/27/2005
Last Updated: 04/28/2005
Overview
The W32.Allim.A and.B worms propagate by sending AOL Instant Messages to all contacts on the compromised computer with imbedded hyperlinks to downloadable copies of the W32.Spybot.Worm .
Details below describe the characteristics of the W32.Allim.A and W32.Allim.B worms 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.Allim worms arrive on the user's PC via an AOL Instant Message from a known contact. The message on the AOL Instant Messenger application displays:
hey check out this!
If the embedded link is selected, a variant of the W32.Spybot.Worm is downloaded, and if executed by the user, the PC will become infected.
Once the W32.Spybot.Worm has been executed, it copies itself to the Windows system directory as well as adds registry entries to ensure that the worm restarts at Windows boot time.
The W32.Spybot.worm is a fully functioning trojan capable of allowing remote execution of commands and termination of system processes. It also enables the infected machine to act as a traffic proxy and attempts to spread through various Microsoft Windows vulnerabilities.
Threat Assessment
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.
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
Two Dragon signatures, "ENSRT:W32-ALLIM-A-001" and "ENSRT:W32-ALLIM-B-001", that detect the W32.Allim worms spreading via the AIM protocol can be retrieved via Dragon Live Update and are located in the Master Library within the ENSRTcategory. Deploy these signatures on Dragon NIDS devices protecting end-user switch ports as well as Internet connections.
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.
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.
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.allim.a.html
http://securityresponse.symantec.com/avcenter/venc/data/w32.allim.b.html
http://securityresponse.symantec.com/avcenter/venc/data/w32.spybot.worm.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: 04/27/2005 |
Author: ENSRT STAFF |
Change |