Flaw in Microsoft's Word software could allow theft of files by bugging document with hidden code

[InfoSec News <isn () c4i org>]

http://www.sfgate.com/cgi-bin/article.cgi?file=/news/archive/2002/09/12/national1632EDT0735.DTL&type=tech

D. IAN HOPPER 
AP Technology Writer 
09-12-2002

WASHINGTON (AP) - Microsoft's flagship word processor has a security
flaw that could allow the theft of computer files by "bugging" a
document with a hidden code, the company disclosed Thursday. It was
exploring how to fix the problem and whether to extend the repair to
an older version of the software still used by millions.

The attack begins when a bugged document goes out, usually with a
request to be revised and returned to the sender -- a common form of
daily communication. When the document is changed and sent back, the
targeted file accompanies it.

"It has the potential of allowing people to get at data that they are
explicitly not allowed to get to," said Woody Leonhard, who has
written books on Microsoft's Word and Office software.

The flaw would most likely occur in the workplace, where Word is the
most prominent word processing program. Potential targets for theft
are sensitive legal contracts, payroll records or e-mails, either from
a hard drive or computer network, depending on the victim's access to
files.

"The issue appears to affect all versions of Microsoft Word,"  
Microsoft said in a statement in response to questions by The
Associated Press. "When the investigation is completed, we will take
the action that best serves Microsoft's customers."

Word 97, an earlier version of the program, is most susceptible to the
attack. Microsoft said it is its policy to no longer repair Word 97,
but said the company is still exploring the issue.

A research firm reported in May that about 32 percent of offices have
copies of Word 97 running, according to a survey of 1,500 high-tech
managers worldwide.

Analyst Laura DiDio of the Yankee Group said the companies are taking
a risk by using such old software. But she said Microsoft should
correct the problem because of its severity. "These are paying
customers," DiDio said.

Leonhard said Word 97 users "bought the package with full faith in
Microsoft and its ability to protect them from this kind of exploit."

Word 97 users may be able to get some help from through Microsoft's
telephone tech support, company spokesman Casey McGee said. But,
referring to Microsoft engineers, McGee said "there's only so far back
they can go."

The flaw involving Word 97 was discovered by Alex Gantman of cellular
phone company Qualcomm and was released on the Internet last month.

An attacker only has to place hidden codes in a Word document, which
is sent to a would-be victim with a request for a response. If the
recipient has Word 97 and revises the Word document, any file sought
by the attacker will be hidden inside the Word document and sent back
to the attacker.

If the intended target uses Word 2000 or 2002, the most recent
versions, the attack will only work if the Word document is printed
first before a reply goes out to the attacker.

After seeing Gantman's work on a public security e-mail forum,
Leonhard found a similar flaw that affects recent Word versions even
when a document is not printed. In this case, the stolen file is
visible within the document, although the attacker can make it hard to
find.

Microsoft says that in both security flaws, an attacker would have to
know the exact file name to be stolen and its location. But many
critical files -- an address book or saved e-mails, for example -- are
usually in obvious or predictable places on every Microsoft Windows
computer.

Microsoft suggests users view hidden codes in every document they
open. In Word 2002, the latest version, that can be done by selecting
tools, options, then checking the "field codes" box. Many companies,
however, use such codes for legitimate and harmless purposes.

Leonhard said that if an attacker tries to steal a very large file,
the victim might notice it when saving or e-mailing the bugged
document. A smaller file might not get that attention.

"It's very much dependent on the greed of the person fishing for a
file," Leonhard said.

On the Net: Microsoft: www.microsoft.com



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