ENSRT Incident Note ETS-i-2005-12575

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.Kalel.A@mm

Release Date: 05/25/2005
Last Updated:

Print this alert

Overview

W32.Kalel.A@mm is a mass-mailing worm that retrieves e-mail addresses from files located on the infected computer and uses an embedded SMTP engine to further proliferate. Additionally, the worm opens a backdoor listener on TCP port 51435 and places copies of itself into file sharing folders to propagate over peer-to-peer networks such as KaZaa.

Details below will describe the characteristics of the W32.Kalel.A@mm as well as provide detection, containment, and prevention techniques available through Enterasys Secure Networks solutions.

Systems affected

Systems not affected

Description

W32.Kalel.A@mm may arrive in a user's mail box or copied from a peer to peer network file share.

Arriving as an e-mail message it will have the following format:

--------------------------------
Subject:
Mail delivery failed: returning message to sender

Message:
This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its recipients. For more details read the attached document.

++ Attachment: No Virus found
++ Symantec AntiVirus֠http:/ /www.symantec.com

Attachment:
error_details.zip
--------------------------------
Once executed it will
- Open a backdoor listener on TCP port 51435 for the purpose of allowing unauthorized remote access to the conquered computer.
- Further procreates by using it's own SMTP engine to send itself via email to addresses found on the infected computer.
- Prevents several programs from running on system startup, including several security related processes.
- Runs continuously as a key stroke logger.
- Copies itself to several system folders for the purpose of propagating through peer to peer file-sharing networks.
- Modifies the system registry in an attempt to configure itself to run at Windows system startup.

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

Detection

A specific Dragon signature to detect the W32.Kalel.A@mm worm can be retrieved via Dragon Live Update and is located in the Master Library within the ENSRT category. The signature "ENSRT:W32-KALEL-A-001" 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 the signature "ENSRT:W32-KALEL-A-001" 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.

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.kalel.a@mm.html
http://www.sophos.com/virusinfo/analyses/w32kalela.html

This document and the information contained herein are intended solely for informational use. Enterasys Networks, Inc. makes no representations or warranties of any kind, whether expressed or implied, with respect to this information and assumes no responsibility for its accuracy or completeness. Enterasys Networks, Inc. hereby disclaims all liability and warranty for any information contained herein and all the material and information herein exists to be used only on an "as is" basis. More specific information may be available on request. By your review and/or use of the information contained herein, you expressly release Enterasys from any and all liability related in any way to this information.    

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:

Version: 1.0

Date: 05/25/2005

Author: ENSRT STAFF

Change