The National Infrastructure Security Co-ordination
Centre, which is responsible for protecting the UK's electronic
infrastructure, has warned of a wide range of flaws affecting
products that rely on one of the internet's basic
protocols.
Software such as e-mail clients, web browsers, anti-virus
products, and mail and web content checkers could be at risk
because of the way they implement MIME, a standard for encoding
e-mail attachments and HTTP content, according to the Unified
Incident Reporting and Alert Scheme (UNIRAS).
The agency identified eight ambiguities in MIME which could
allow dangerous content to slip past detection systems. Information
security consultancy Corsaire, which provided the research, did not
specify which products were affected, but both organisations said
vulnerabilities were widespread.
"If a content checker were to parse a MIME message incorrectly
and to allow the content to pass through the checker based on an
incorrect assessment of its MIME type, the security of the content
checker could be bypassed," UNIRAS said.
"If this happened or a content checker was not used, the
receiving client could crash or execute arbitrary code if it also
parsed the MIME incorrectly."
Corsaire identified the vulnerabilities between June and August
2003 and the centre been working with affected suppliers since
then, many of whom have already silently released patches, Corsaire
said.
The firm said that if companies have kept up to date with
patches on their MIME-based products, they should be protected.
However, the only way for them to be sure they are not affected is
to contact their suppliers.
A handful of software suppliers provided statements to UNIRAS
clarifying the status of their MIME-based products, with Apple,
Fujitsu, Hewlett-Packard, IBM, MessageLabs and Sun Microsystems'
Mozilla browser team all saying their products were not
affected.
PLDaniels Software said versions of its ripMIME product prior to
1.4.0.0 were affected by several of the issues, but the problems
have now been fixed.
F-Secure said its workstation products are not vulnerable, but
the F-Secure Internet Gatekeeper failed in four of the tests and
would be fixed with release 6.41 this autumn.
The problems, detailed by UNIRAS, arose from anomalous parameter
values in MIME headers and MIME encodings that do not parse
correctly.
"This kind of deliberate corruption has already been used by a
number of high-profile viruses and worms, such as Nimda, Netsky and
Badtrans," Corsaire said.
Matthew Broersma writes for Techworld