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Security Advisories Relating to Symantec Products - Specifically Crafted Archive/Container Files can Bypass Initial Scans


June 12, 2009

Revision History





Specifically-crafted archive and container files can potentially bypass initial malware scans in some products.

Symantec Mail Security for Domino
Symantec Mail Security for Microsoft Exchange
Symantec Mail Security for SMTP
Symantec Brightmail Gateway
Symantec AntiVirus for Network Attached Storage
Symantec AntiVirus for Caching
Symantec AntiVirus for Messaging
Symantec Protection for SharePoint Servers
Symantec Protection Suite
Symantec Scan Engine
Symantec Client Security
Symantec Endpoint Protection
Symantec AntiVirus Corporate Edition
Norton Internet Security
Norton 360
Norton AntiVirus
Norton Systemworks


Symantec received information on various malformed or specifically formatted archive or container files, tar/zip/rar/pdf etc. that have the potential of bypassing scans in some scanning products. Depending on the product doing the initial scanning of the archive or container file, this can sometimes result in files, which haven’t been properly content scanned, reaching client systems. While these modified files many times are corrupted out of any expected format, some applications will still recognize them and attempt to extract or read the content.

Symantec Response

Symantec is well aware of the potential for malicious use of malformed archive/container files. Symantec gateway products detect malformed files, such as a malformed archive or container file, by default. Administrative policy controls exist in Symantec gateway products for these types of malformed files to be blocked or stripped prior to entering the network or quarantined for admin review and actions. Symantec recommends such policy control be used as part of a “defense-in-depth” security policy to restrict potentially harmful content from entering the internal network.

In the event that these malformed files get through to client/end-user systems, potential malware archived in this manner is not an active threat while it remains archived. However, should known malicious code be delivered to a client system in this manner, Symantec’s Auto Protect or Real Time Virus Scan components would detect malicious content during access attempts as the container or file is opened.

Should previously unidentified malicious code be distributed in this manner, Symantec’s Security Response is committed to react immediately with updated threat detections via Symantec LiveUpdate or Rapid Release Definitions.

Best Practices

As part of normal best practices, Symantec strongly recommends:
  • Restrict access to administration or management systems to privileged users.
  • Restrict remote access, if required, to trusted/authorized systems only.
  • Run under the principle of least privilege where possible to limit the impact of exploit by threats.
  • Keep all operating systems and applications updated with the latest vendor patches.
  • Follow a multi-layered approach to security. Run both firewall and anti-malware applications, at a minimum, to provide multiple points of detection and protection to both inbound and outbound threats.
  • Be cautious of unsolicited attachments and executables delivered via email or via instant messaging.
  • Do not open email from unknown sources.
  • Do not follow links or download content provided by unknown or untrusted sources.
  • Email addresses can easily be spoofed so a message appears to come from someone you know. If a message seems suspicious or is unexpected, contact the sender before opening attachments or following web links.


Symantec would like to thank Thierry Zoller for identifying these malformed formats.


Symantec takes the security and proper functionality of our products very seriously. As founding members of the Organization for Internet Safety (OISafety), Symantec supports and follows responsible disclosure guidelines.
Symantec has developed a Software Security Vulnerability Management Process document outlining the process we follow in addressing suspected vulnerabilities in our products.
Symantec Corporation firmly believes in a proactive approach to secure software development and implements security review into various stages of the software development process. Additionally, Symantec is committed to the security of its products and services as well as to its customers’ data. Symantec is committed to continually improving its software security process.
This document provides an overview of the current Secure Development Lifecycle (SDLC) practice applicable to Symantec’s product and service teams as well as other software security related activities and policies used by such teams. This document is intended as a summary and does not represent a comprehensive list of security testing and practices conducted by Symantec in the software development process.
Please contact secure@symantec.com if you believe you have discovered a security issue in a Symantec product. A member of the Symantec Software Security team will contact you regarding your submission to coordinate any required response. Symantec strongly recommends using encrypted email for reporting vulnerability information to secure@symantec.com.
The Symantec Software Security PGP key can be found at the following location:
Permission to redistribute this alert electronically is granted as long as it is not edited in any way unless authorized by Symantec Software Security. Reprinting the whole or part of this alert in any medium other than electronically requires permission from secure@symantec.com.
Last modified on: June 12, 2009
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