Microsoft’s recent efforts to fix yet another vulnerability in Internet Explorer and end the latest series of internet attacks, doesn’t address another closely related and dangerous vulnerability, according to a security specialist.
Dutch security expert Jelmer Kuperus published code on the web last week that he says can be used to break into fully patched Windows systems using a slightly modified version of an attack called Download.Ject that Microsoft patched two weeks ago.
The new attack targets a hole in a different Windows component than the one addressed by Microsoft's software patch. Using a similar attack, malicious hackers could break into patched Windows machines, Kuperus says.
Microsoft confirmed last week that it is aware of the exploit code, but does not believe any customers have been attacked using the Shell.Application exploit, a US spokeswoman said.
Microsoft’s security update for Internet Explorer 6.0 was meant to end the threat of Download.Ject by disabling a Windows component called ADODB.Stream, which was allegedly being used by a Russian criminal gang called the Hangup Team to install malicious code on computers.
By attacking a different Windows ActiveX component called Shell.Application, hackers can still load malicious code onto machines. The attack relies on a vulnerability in Shell.Application discovered and disclosed in January by a security expert known by the online handle "http-equiv," Kuperus says.
To prove his point, Kuperus posted a copy of attack code that targets the Shell.Application component on a web site he maintains. Web surfers that use Windows XP with IE and visit the page are confronted with a screen that freezes Windows. According to Kuperus this example is harmless, but the exploit could be used in the same way the group of Russian criminals exploited the ADODB.Stream vulnerability in a series of attacks in June.
Those attacks combined compromises in unpatched Microsoft Internet Information Services (IIS) web servers with attacks using two vulnerabilities in Windows and Internet Explorer. Web surfers visiting compromised web sites had malicious code secretly downloaded to run on their systems. When run, the code redirected web browsers to sites controlled by the hackers, from which personal data was downloaded and a Trojan horse program installed to capture keystrokes.
Kuperus joined the expert known as http-equiv to create computer code that demonstrated the Shell.Application vulnerability. After the attacks in June, the two anticipated the patch issued by Microsoft would not be comprehensive and began writing a new exploit before Microsoft actually plugged the ADODB.Stream vulnerability.
A few hours after Microsoft issued its latest update, Kuperus posted the new exploit on his site.
"We discovered that by simply switching components, the exploit is back in business," Kuperus says.
Microsoft acknowledged that the Shell.Application has similar capabilities to the ADODB.Stream component. However, it does not yet have configuration changes to address the vulnerability, as it did with ADODB.Stream, a spokeswoman says.
Microsoft is investigating the issue and is planning a series of new updates to IE in the coming weeks that will provide additional security for its customers, said the spokeswoman.