32713 : Apple iChat Improper TXT Key Hash Handling DoS
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Info

Last Modified
about 1 year ago

Percent Complete
100%

Disclosure
Jan 29, 2007

Discovery
Unknown

Dates

Exploit
Jan 29, 2007

Solution
Unknown

Description

 Apple iChat improperly parses TXT key hashes which may allow a remote denial of service. The issue is triggered when the Apple iChat Agent receives a specially crafted TXT key hash via Bonjour triggering a NULL pointer dereference and resulting in a loss of availability for the iChat service.

Classification

 Location: Remote / Network Access
Attack Type: Denial of Service
Impact: Loss of Availability
Exploit: Exploit Public
Disclosure: OSVDB Verified

Technical

 - Since the exploitation vector is Bonjour, which is a broadcasting service, one can use the exploit to affect a large number of users which can be reached via service advertisements, however, the remote attacker has to be on the same multicast network as the user.
- A specially crafted TXT key hash sent via the Bonjour service will cause the iChat Agent to raise an exception (SIGTRAP signal 0x9262050b in _NSRaiseError()) due to a NULL pointer dereference.
- The PoC author noted that this should be considered an issue in Bonjour's mDNSResponder daemon as well since iChat isn't involved in the processing of any mDNS service advertisements. mDNSResponder stops responding shortly after abuse and trying to launch iChat Bonjour functionality again will fail since mDNSResponder keeps the crafted record.

Solution

 Download and install Security Update 2007-002 (PPC) via Software Update preferences, or from Apple Downloads, as it has been reported to fix this vulnerability. It is also possible to correct the flaw by implementing the following workaround(s):
- Do not use iChat with the Bonjour service.
or
- Disable mDNSResponder using the following (by author):
sudo launchctl unload /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
sudo mv /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist \
/Users/Shared/com.apple.mDNSResponder.plist.BACKUP

Products
Apple Computer, Inc.
Watch-list
Mac OS X
Watch-list
 10.3.9
10.4.8
iChat
Watch-list
 3.1.6

References

Tools & Filters
24354

Credit
  • Lance M. Havok - lmhinfo-pull.com -

CVSSv2 Score

CVSSv2 Base Score = 2.1
Source: nvd.nist.gov | Generated: 2007-02-20 | Disagree? | There are 1 more: View All

Access_vector_0 Access_complexity_2 Authentication_2 Confidentiality_impact_0 Integrity_impact_0 Availability_impact_1

Blogs

This product uses the Daylife API but is not endorsed or certified by Daylife.

This section lists the latest news and blogs found via the daylife API (and for older items, the technorati API), which mention or otherwise discuss this vulnerability.

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