[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[ISN] Microsoft again ups risk rating on an IE flaw
By Joris Evers
IDG News Service
For the second time this month Microsoft will raise the risk rating on
a flaw affecting Internet Explorer (IE) after experts told the company
it underrated the issue.
The cumulative patch announced on Nov. 20 in Microsoft's security
bulletin MS02-066 for the IE Web browser will now be rated "critical,"
up from "important," Steve Lipner, director of security assurance at
Microsoft, said in a statement sent via e-mail on Friday.
Microsoft initially thought a buffer overrun that results when PNG
(Portable Network Graphics) files are opened could only be exploited
to cause IE, Microsoft Office applications or the Microsoft Index
Server to fail. Now Microsoft warns that successful exploitation of
the flaw could allow an attacker to gain control over a user's
Security vendor eEye Digital Security, the discoverers of the PNG
vulnerability, earlier this week said the flaw should get the highest
risk rating as it allowed an attacker to run code on a victim's PC. As
a result, Microsoft is raising the severity rating of bulletin
MS02-066, although it has not yet been able to verify the exploit,
Buffer overrun flaws generally allow an attacker to take over a user's
machine. An attacker exploits an unchecked buffer in a program to load
his own code onto a system and run it.
This is the second time this month that Microsoft has been forced to
increase the severity rating on a security vulnerability affecting IE,
the Web browser used by millions worldwide. Last week, Microsoft
increased from "moderate" to "critical" the rating on a flaw in an IE
security feature discovered by GreyMagic Software of Israel.
After reexamining that issue, Microsoft said it found a new exploit
scenario that could allow a malicious user to run code on a user's
computer via a specially crafted Web site or e-mail message,
warranting a severity rating of critical, it said.
Under Microsoft's security rating system, changed last month, critical
vulnerabilities are those that could be exploited to allow Internet
worms to spread without user action. Vulnerabilities rated "important"
are those that could expose user data or threaten system resources.
The two other ratings are "moderate" and "low" and are given depending
on how difficult it is to exploit a flaw.
"We are continuing to review our processes for reproducing reported
vulnerabilities, and for working with external security researchers to
ensure that our severity ratings are as accurate as possible," said
The cumulative patch announced in MS02-066 provided all previously
released fixes for IE 5.01, IE 5.5 and IE 6.0 and patched six other
new vulnerabilities. To exploit the PNG vulnerability, an attacker
would have to lure a user to a Web site hosting a deliberately
malformed PNG file, Microsoft said. According to eEye, an e-mail-based
attack is also possible.
The patch announced in bulletin MS02-066 does eliminate the
vulnerability. Microsoft notes that users should no longer install
this cumulative patch, as it has been superseded by a new one. The
latest super patch for IE, which includes all previously released
patches, was announced in bulletin MS02-068 on Dec. 4 and is rated
"We strongly encourage customers to apply the patch for MS02-068,"
More details on the PNG flaw can be found in Microsoft security
bulletin MS02-066 here 
ISN is currently hosted by Attrition.org
To unsubscribe email majordomo@xxxxxxxxxxxxx with 'unsubscribe isn'
in the BODY of the mail.