[SA18963] Mac OS X "__MACOSX" ZIP Archive Shell Script Execution

TITLE:
Mac OS X "__MACOSX" ZIP Archive Shell Script Execution

SECUNIA ADVISORY ID:
SA18963

VERIFY ADVISORY:
http://secunia.com/advisories/18963/

CRITICAL:
Extremely critical

IMPACT:
System access

WHERE:
>From remote

OPERATING SYSTEM:
Apple Macintosh OS X
http://secunia.com/product/96/

DESCRIPTION:
Michael Lehn has discovered a vulnerability in Mac OS X, which can be
exploited by malicious people to compromise a user's system.

The vulnerability is caused due to an error in the processing of file
association meta data (stored in the "__MACOSX" folder) in ZIP
archives. This can be exploited to trick users into executing a
malicious shell script renamed to a safe file extension stored in a
ZIP archive.

This can also be exploited automatically via the Safari browser when
visiting a malicious web site.

Secunia has constructed a test, which can be used to check if your
system is affected by this issue:
http://secunia.com/mac_os_x_command_execution_vulnerability_test/

The vulnerability has been confirmed on a fully patched system with
Safari 2.0.3 (417.8) and Mac OS X 10.4.5.

SOLUTION:
The vulnerability can be mitigated by disabling the "Open safe files
after downloading" option in Safari.

Do not open files in ZIP archives originating from untrusted sources.

PROVIDED AND/OR DISCOVERED BY:
Michael Lehn

---

About:
This Advisory was delivered by Secunia as a free service to help
everybody keeping their systems up to date against the latest
vulnerabilities.

Subscribe:
http://secunia.com/secunia_security_advisories/

Definitions: (Criticality, Where etc.)
http://secunia.com/about_secunia_advisories/

Please Note:
Secunia recommends that you verify all advisories you receive by
clicking the link.
Secunia NEVER sends attached files with advisories.
Secunia does not advise people to install third party patches, only
use those supplied by the vendor.