Risk: Medium
Microsoft is investigating the report of a flaw that could open systems using its Access or Office software up to attack.
The vulnerability, which was not one of eight patched by Microsoft in its April 2005 patch train, is in the Jet database engine component, according to an advisory posted at the same time. It could enable an intruder to remotely execute malicious code on a vulnerable PC.
Microsoft has not confirmed the existence of the security hole, which potentially affects software including Microsoft Office and the Microsoft Access database program.
The problem has been rated as "highly critical", noting that exploit code for the flaw had been shared on a public mailing list.
The vulnerability is caused by a memory handling error when parsing database files. This can be exploited to execute arbitrary code by tricking a user into opening a specially crafted '.mdb' file in Microsoft Access."
A Microsoft representative commented that the company has not heard of any attacks on customers' systems that exploited this hole.
"We are aware of the exploit code that has been released," the Microsoft representative said, adding that the software maker would take appropriate action once it has completed its investigation of the problem.
The original alert regarding the flaw came from a security research firm called HexView.
Continuing an ongoing debate about when and how flaw finders should disclose vulnerabilities, Microsoft criticised the researchers for going public with the vulnerability, rather than privately contacting the software maker so a patch could be released as soon as the flaw was disclosed.
"It is unfortunate that this researcher decided to post publicly," the Microsoft representative said.
HexView said in its own advisory that it notified Microsoft of the flaw on March 30, but had received no response.
A Microsoft representative said the company had no record of any contact from HexView before the flaw was publicised.
Word of the problem came on the same day that Microsoft released fixes for eight other flaws, several of them critical, and some of them revealed publicly for the first time in the company's monthly security bulletin.