iPhone 2.1 Firmware Fixes 6 Security Issues

Apple has fixed six iPhone security problems with the release of the latest 2.1 firmware.

Application Sandbox
- The Application Sandbox does not properly enforce access restrictions between third-party applications. This may allow a third-party application to read files in another third-party application's sandbox, and lead to the disclosure of sensitive information. This update addresses the issue by enforcing the proper access restrictions between application sandboxes. Credit to Nicolas Seriot of Sen:te and Bryce Cogswell for reporting this issue. This issue does not affect iPhone versions prior to v2.0.

CoreGraphics
- Multiple vulnerabilities exist in FreeType v2.3.5, the most serious of which may lead to arbitrary code execution when accessing maliciously crafted font data. This update addresses the issue by incorporating the security fixes from version 2.3.6 of FreeType. Further information is available via the FreeType site at http://www.freetype.org/

mDNSResponder
- mDNSResponder provides translation between host names and IP addresses for applications that use its unicast DNS resolution API. A weakness in the DNS protocol may allow a remote attacker to perform DNS cache poisoning attacks. As a result, applications that rely on mDNSResponder for DNS may receive forged information. This update addresses the issue by implementing source port and transaction ID randomization to improve resilience against cache poisoning attacks. Credit to Dan Kaminsky of IOActive for reporting this issue.

Networking
- TCP initial sequence numbers are sequentially generated. Predictable initial sequence numbers may allow a remote attacker to create a spoofed TCP connection or insert data into an existing TCP connection. This update addresses the issue by generating random TCP initial sequence numbers. This issue does not affect iPhone versions prior to v2.0.

Passcode Lock
- The Passcode Lock feature is designed to prevent applications from being launched unless the correct passcode is entered. An implementation issue in the handling of emergency calls allows users with physical access to an iPhone to launch an application without the passcode by double clicking the home button in emergency call. This update addresses the issue through improved handling of emergency calls. Credit to Matthew Yohe of The University of Iowa's Department of Electrical and Computer Engineering for reporting this issue. This issue does not affect iPhone versions prior to v2.0.

WebKit
- A use-after-free issue exists in WebKit's handling of CSS import statements. Visiting a maliciously crafted website may lead to an unexpected application termination or arbitrary code execution. This update addresses the issue through improved handling of document references.

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