Title: Buffer Overrun in SmartHTML Interpreter Could Allow
Code Execution (Q324096)
Released: 25 September 2002
Software: FrontPage Server Extensions 2000 and 2002
Impact: Denial of service or privilege elevation
Max Risk: Critical
Bulletin: MS02-053

Microsoft encourages customers to review the Security Bulletin at:
http://www.microsoft.com/technet/security/bulletin/MS02-053.asp.

Issue:

The SmartHTML Interpreter (shtml.dll) is part of the FrontPage
Server Extensions (FPSE), and provides support for web forms and
other FrontPage-based dynamic content. The interpreter contains a
flaw that could be exposed when processing a request for a particular
type of web file, if the request had certain specific character-
istics. This flaw affects the two versions of FrontPage Server
Extensions differently. On FrontPage Server Extensions 2000, such
a request would cause the interpreter to consume most or all CPU
availability until the web service was restarted. An attacker could
use this vulnerability to conduct a denial of service attack against
an affected web server. On FrontPage Server Extensions 2002, the
same type of request could cause a buffer overrun, potentially
allowing an attacker to run code of his choice.

Mitigating Factors:

• • The IIS Lockdown Tool, if used to configure a static web server,
    disables the SmartHTML Interpreter. Servers on which this has
    been done could not be affected by the vulnerability.
• • FrontPage Server Extensions install on IIS 4.0, 5.0 and 5.1 by
    default, but can be uninstalled if desired. Servers on which
    this has been done could not be affected by the vulnerability.

Risk Rating:

• Internet systems: Critical
• Intranet systems: Moderate
• Client systems: None

Patch Availability:

• A patch is available to fix this vulnerability. Please read the
  Security Bulletin at
  http://www.microsoft.com/technet/security/bulletin/ms02-053.asp
  for information on obtaining this patch.

Acknowledgment:

Microsoft thanks Maninder Bharadwaj ([email protected])
of Digital GlobalSoft Ltd. for reporting this issue to us and
working with us to protect customers.

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