F-Secure Security Bulletin FSC-2007-5
Scan bypass vulnerabilities in handling of specially crafted LHA and RAR archives

Date issued

2007-06-19

Last updated

2007-06-18

Risk factor

Medium (Low/Medium/High/Critical)

Brief description

Several F-Secure products are affected by archive file scan bypass vulnerabilities:

- user decompressable, crafted RAR archives cannot be parsed (opened) by Anti-Virus

- user decompressable, crafted LHA archives cannot be parsed (opened) by Anti-Virus

Software

F-Secure's Anti-Virus products for Microsoft Windows and Linux

Affected versions

F-Secure Anti-Virus for Workstations version 7.00 and earlier
F-Secure Anti-Virus for Windows Servers version 7.00 and earlier
F-Secure Anti-Virus for Citrix Servers version 5.52
F-Secure Anti-Virus for MIMEsweeper version 5.61 and earlier
F-Secure Client Security version 7.00 and earlier
F-Secure Anti-Virus for MS Exchange version 7.00 and earlier
F-Secure Internet Gatekeeper version 6.61 and earlier
F-Secure Internet Security 2005, 2006 and 2007
F-Secure Anti-Virus 2005, 2006 and 2007
Solutions based on F-Secure Protection Service for Consumers version 7.00 and earlier
F-Secure Anti-Virus for Linux Servers version 4.65 and earlier
F-Secure Anti-Virus for Linux Gateways version 4.65 and earlier
F-Secure Linux Client Security 5.52 and earlier
F-Secure Linux Server Security 5.52 and earlier
F-Secure Internet Gatekeeper for Linux 2.16 and earlier

Affected platforms

All platforms supported by the affected products

Bulletin location

http://www.f-secure.com/security/fsc-2007-5.shtml

Issue:

An attacker may create a specially crafted LHA or RAR archive file with manipulated archive file header fields and malicious contents, which then goes through Anti-Virus scanning without interception.

 

The manipulated file header fields basically break the archive file from Anti-Virus point of view, but certain decompression programs are still capable of opening archive for the user, in some cases with errors displayed.


Workstation products:

F-Secure Internet Security 2005, 2006 and 2007
F-Secure Anti-Virus 2005, 2006 and 2007
Solutions based on F-Secure Protection Service for Consumers version 7.00 and earlier

F-Secure Client Security version 7.00 and earlier

F-Secure Anti-Virus for Workstations 7.00 and earlier

F-Secure Linux Client Security 5.52 and earlier

Risk Factor:

Low

These products contain the described vulnerabilities, but do not scan inside archives by default, except by their possible e-mail scanning component. Archive contents that evade the detection in initial scanning, will be intercepted at the time of decompression.

Recent antivirus database updates have automatically fixed both of the mentioned issues, without any intervention needed by the user/administrator.


Server products:

F-Secure Anti-Virus for Windows Servers 7.00 and earlier
F-Secure Anti-Virus for Citrix Servers version 5.52 and earlier

F-Secure Linux Server Security 5.52 and earlier
F-Secure Anti-Virus for Linux Servers version 4.65 and earlier

Risk Factor:

Low

These products contain the described vulnerabilities, but do not scan inside archives by default.

Recent antivirus database updates have automatically fixed both of the mentioned issues, without any intervention needed by the user/administrator.


Gateway products:

F-Secure Internet Gatekeeper 6.61 and earlier
F-Secure Anti-Virus for MS Exchange version 7.00 and earlier
F-Secure Anti-Virus for Linux Gateways version 4.65 and earlier
F-Secure Internet Gatekeeper for Linux 2.16

Risk Factor:

High

 

These gateway products typically scan inside archives, thus are affected by the vulnerability. However antivirus software on the receiving clients intercept the malicious contents at the point of archive decompression by the user.

 

Recent antivirus database updates have automatically fixed both of the mentioned issues, without any intervention needed by the user/administrator.


Gateways products:

F-Secure Anti-Virus for MIMEsweeper 5.61 and earlier

Risk Factor:

Medium

F-Secure Anti-Virus for MIMEsweeper does not handle archives. Archives are handled by MIMEsweeper and this vulnerability does not affect the reliability of such systems. The vulnerability does however affect the virus scanner's ability to detect malware that is stored in archives on the disk of the computer that runs MIMEsweeper. The impact of this is however minimal in the default configuration.

Recent antivirus database updates have automatically fixed both of the mentioned issues, without any intervention needed by the user/administrator.


Mitigating Factors:

  • Exploitation of the vulnerabilities requires specially crafted archives.
  • Vulnerability in archive scanning concerns only those products that scan inside archives by default (gateway solutions).
  • These issues have been fixed automatically in F-Secure database updates. This applies all the affected product versions with the exception of deployments not using automatic or automated scripts for the updates.

Patch availability:

 

Product

Versions

Hotfix ID

Download

F-Secure Internet Security 2005 - 2007

2005 - 2007

Fixed automatically in database updates

F-Secure Anti-Virus 2005 - 2007

2005 - 2007

F-Secure Protection Service for Consumers

5.00 - 7.00

F-Secure Anti-Virus for Workstations

5.44 - 7.00

F-Secure Client Security

6.00 – 7.00

F-Secure Anti-Virus for Windows Servers

5.50 - 7.00

F-Secure Anti-Virus for Citrix Servers

5.50 - 5.52

F-Secure Anti-Virus for MIMEsweeper

5.61

F-Secure Anti-Virus for MS Exchange

6.01

F-Secure Anti-Virus for MS Exchange

6.61 – 7.00

F-Secure Internet Gatekeeper

6.60 - 6.61

F-Secure Anti-Virus for Linux Servers

4.64 - 4.65

F-Secure Anti-Virus for Linux Gateways

4.64 - 4.65

F-Secure Linux Client Security

5.30 - 5.52

F-Secure Linux Server Security

5.30 - 5.52

F-Secure Internet Gatekeeper for Linux

2.16

Credits: F-Secure wants to thank Thierry Zoller in n.runs AG (http://www.nruns.com/) for reporting these issues.

Revision History:

FSC-2007-5 - 2007-06-15

 

 

Contact Information:
Support: http://support.f-secure.com/enu/home/contactus/
Security: http://www.f-secure.com/security/
URL: http://www.f-secure.com/