ZDI-06-017: Microsoft Internet Explorer UTF-8 Decoding Heap Overflow Vulnerability

ZDI-06-017: Microsoft Internet Explorer UTF-8 Decoding Heap Overflow
June 13, 2006

-- CVE ID:

-- Affected Vendor:

-- Affected Products:
Internet Explorer 6 All Versions
Internet Explorer 5 SP4

-- TippingPoint(TM) IPS Customer Protection:
TippingPoint IPS customers have been protected against this
vulnerability since June 13, 2006 by Digital Vaccine protection
filter ID 4440. For further product information on the TippingPoint IPS:


-- Vulnerability Details:
This vulnerability allows remote attackers to execute arbitrary code on
vulnerable installations of Microsoft Internet Explorer. Successful
exploitation requires that the target user browse to a malicious web
page. Exploitaton does not require JavaScript, Java or ActiveX to be

The specific vulnerability is due to a miscalculation of memory sizes
when translating UTF-8 characters to Unicode. A size mismatch between a
heap allocation and memory copy results in an exploitable heap

-- Vendor Response:
Microsoft has issued an update to correct this vulnerability. More
details can be found at:

-- Disclosure Timeline:
2006.01.20 - Vulnerability reported to vendor
2006.06.13 - Digital Vaccine released to TippingPoint customers
2006.06.13 - Coordinated public release of advisory

-- Credit:
This vulnerability was discovered by an anonymous researcher.

-- About the Zero Day Initiative (ZDI):
Established by TippingPoint, a division of 3Com, The Zero Day Initiative
(ZDI) represents a best-of-breed model for rewarding security
researchers for responsibly disclosing discovered vulnerabilities.

Researchers interested in getting paid for their security research
through the ZDI can find more information and sign-up at:


The ZDI is unique in how the acquired vulnerability information is used.
3Com does not re-sell the vulnerability details or any exploit code.
Instead, upon notifying the affected product vendor, 3Com provides its
customers with zero day protection through its intrusion prevention
technology. Explicit details regarding the specifics of the
vulnerability are not exposed to any parties until an official vendor
patch is publicly available. Furthermore, with the altruistic aim of
helping to secure a broader user base, 3Com provides this vulnerability
information confidentially to security vendors (including competitors)
who have a vulnerability protection or mitigation product.

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