Windows: Denial of Service -- Remote with User Interaction

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2017.2530
          (0Day) Microsoft Windows WAV File Uninitialized Pointer
                     Denial of Service 
Vulnerability
                              9 October 2017

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Windows
Publisher:         Zero Day Initiative
Operating System:  Windows
Impact/Access:     Denial of Service -- Remote with User Interaction
Resolution:        Mitigation

Original Bulletin: 
   http://www.zerodayinitiative.com/advisories/ZDI-17-838

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(0Day) Microsoft Windows WAV File Uninitialized Pointer Denial of Service 
Vulnerability

ZDI-17-838: October 6th, 2017

CVSS Score

5, (AV:N/AC:L/Au:N/C:N/I:N/A:P)

Affected Vendors

Microsoft

Affected Products

Windows

Vulnerability Details

This vulnerability allows remote attackers to cause a denial-of-service 
condition on vulnerable installations of Microsoft Windows. User interaction 
is required to exploit this vulnerability in that the target must visit a 
malicious page or open a malicious file.

The specific flaw exists within the processing of WAV audio files. The issue 
results from the lack of proper initialization of a pointer prior to accessing
it. An attacker can leverage this vulnerability to create a denial-of-service
condition in the context of the Explorer process or other current process.

Vendor Response

Microsoft states:

This vulnerability is being disclosed publicly without a patch in accordance 
with the ZDI 120 day deadline.

09/01/17 - ZDI disclosed the report to the vendor.

09/01/17 - The vendor acknowledged the report and provided a case manager and
a tracking number.

09/15/17 - The vendor responded that "We have finished our investigation into
this report and determined this does not meet our bar for servicing a 
downlevel security patch. This requires user interaction to trigger and is not
a persistent DOS. Our analysis has determined it does not bugcheck. A 
blackscreen will show and explorer.exe will restart. Can you confirm your 
disclosure timeline?"

09/15/17 - ZDI advised the vendor that this report will 0-day on 10/06/17.

- -- Mitigation:

Given the nature of the vulnerability the only salient mitigation strategy is
to restrict interaction with the application to trusted files.

Disclosure Timeline

2017-09-01 - Vulnerability reported to vendor

2017-10-06 - Coordinated public release of advisory

Credit

This vulnerability was discovered by:

Andre Fassbender

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