Feeds

Microsoft IIS hole gives System-level access

Redmond "strongly urges" patching "immediately"

  • alert
  • submit to reddit

Build a business case: developing custom apps

Strong words from the official voice of Redmond today, urging admins to patch a recently-discovered buffer overflow vulnerability in servers running IIS 5.0 on Windows 2000 Server, Windows 2000 Advanced Server and Windows 2000 Datacenter Server, make it clear how serious a security problem the Beast has on its hands.

"Microsoft strongly urges all IIS 5.0 server administrators to install the patch immediately," a company security bulletin says.

The vulnerability was discovered less than a fortnight ago by engineers from eEye Digital Security, while upgrading a network scanner it makes called Retina.

Once upgraded to audit the .printer ISAPI (Internet Server Application Programming Interface) filter (C:\WINNT\System32\msw3prt.dll), which enables Web-based control of networked printers, the Retina implementation reported a buffer overflow which eEye soon found to be exploitable.

Web-based printer support is enabled by default in IIS, unfortunately, so a great many users will be affected.

The vulnerability occurs when a buffer of approximately 420 bytes is sent within the HTTP Host: header for a .printer ISAPI request. Because Win 2K is equipped with a lovely feature which automatically restarts the Web server after a crash, an attacker can gain easy access.

"There are roughly five million Web sites running IIS," eEye Chief Hacking Officer Marc Maiffret told The Register. "If only one million users have upgraded to IIS 5.0 -- a conservative estimate -- then it's obvious how serious this is."

We spoke also with Bill Wall, Chief Computer Security Engineer with the STAT division of Harris Corporation, who confirmed with his own tests that the eEye exploit does in fact work as advertised, quickly and easily giving up system-level control of a Win2K machine.

It's hardly a mystery that a flaw like this exists. The issue, he said, is that the ISAPI filter does inadequate bounds checking on buffers, which leaves the system vulnerable to buffer overflow attacks. "With millions of lines of code to audit, it's no surprise to find calls without adequate limitations," he noted.

"Roughly eighty per cent of vulnerabilities are actually buffer overflows," Wall estimated.

Harris's competing product, STAT Scanner, will be upgraded to include the eEye vulnerability within a few days, he told us.

Marketing windfall

The timing of this discovery couldn't be handier for eEye, as it's got an application firewall called SecureIIS, which works within the IIS process monitoring all incoming requests for signs of attack, which it can then shut down automatically.

As fate would have it, eEye had distributed beta versions of SecureIIS just before it discovered the printer vulnerability. Testers have reported that their systems are not susceptible to it, even though their versions of SecureIIS were developed before it could be taken into account.

Naturally we had to question eEye's Maiffret about the extraordinary convenience, from a marketing perspective, in the timing of today's announcement.

"That's a fair suspicion," he said affably. "But we're confident that it will catch the next one, and the one after that, without any modification or input from users."

We're sure he knows we'll be monitoring this in future, which does lend an air of credibility to the claim. ®

Maximizing your infrastructure through virtualization

More from The Register

next story
Whoah! How many Google Play apps want to read your texts?
Google's app permissions far too lax – security firm survey
Chrome browser has been DRAINING PC batteries for YEARS
Google is only now fixing ancient, energy-sapping bug
Do YOU work at Microsoft? Um. Are you SURE about that?
Nokia and marketing types first to get the bullet, says report
Microsoft takes on Chromebook with low-cost Windows laptops
Redmond's chief salesman: We're taking 'hard' decisions
EU dons gloves, pokes Google's deals with Android mobe makers
El Reg cops a squint at investigatory letters
Big Blue Apple: IBM to sell iPads, iPhones to enterprises
iOS/2 gear loaded with apps for big biz ... uh oh BlackBerry
OpenWRT gets native IPv6 slurping in major refresh
Also faster init and a new packages system
Google shows off new Chrome OS look
Athena springs full-grown from Chromium project's head
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
The Essential Guide to IT Transformation
ServiceNow discusses three IT transformations that can help CIO's automate IT services to transform IT and the enterprise.
Mobile application security vulnerability report
The alarming realities regarding the sheer number of applications vulnerable to attack, and the most common and easily addressable vulnerability errors.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.