ENSRT Incident Note ETS-i-2004-12511

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.Erkez.D@mm

Release Date: 12/15/2004
Last Updated:

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Overview

The W32.Erkez.D@mm mass mailer worm infects network PCs through an e-mail's attached executable and then attempts further proliferation with an imbedded SMTP mail engine as well as by opening a backdoor communications channel.

Also Known As: Win32.Zafi.D [Computer Associates], Zafi.D [F-Secure], W32/Zafi.d@MM [McAfee], W32/Zafi.D.worm [Panda], W32/Zafi-D [Sophos], WORM_ZAFI.D [Trend Micro]

Systems affected

Windows operating systems

Systems not affected

Linux and MAC/OSX

Description

The W32.Erkez.D@mm worm arrives in the user mailbox containing a subject line matching one of the following holiday greetings:

Merry Christmas!
boldog karacsony...
Feliz Navidad!
ecard.ru
Christmas Kort!
Christmas Vykort!
Christmas Postkort!
Christmas postikorti!
Christmas - Kartki!
Weihnachten card.
Prettige Kerstdagen!
Christmas pohlednice
Joyeux Noel!
Buon Natale!

Attached to the worm-ridden e-mail is an executable with one of the following extensions: ".bat", ".cmd", ".com", ".pif", or ".zip". If the attachment is executed by the user, the worm installs itself into the Windows system folder on the newly infected machine. Additionally, it adds registry values to load the virus on system bootup. The worm also displays a message with the content "Error in packed file!".

The next phase of the W32.Erkez.D@mm worm's attack is to create a backdoor communications channel by listening on TCP port 8181 for commands originating from remote attackers as well as terminating security related software.

Lastly, the worm collects e-mail addresses from the infected system and attempts further worm proliferation by sending a copy of itself with an imbedded SMTP engine to the collected addresses.

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

Detection

Updated IDS signatures can be downloaded here: https://dragon.enterasys.com (requires login)

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.

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.Erkez.D@mm worm's backdoor communication channel listening on TCP port 8181.

This NetSight PMD file can be downloaded from here: http://www.enterasys.com/support/pmd.html?12511

Repair

Scan all clients and servers for newly opened TCP ports (in this case TCP port 8181) 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://www.iana.org/assignments/port-numbers
http://securityresponse.symantec.com/avcenter/venc/data/w32.erkez.d@mm.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: 12/15/2004

Author: ENSRT STAFF

Change

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