Feeds

Steve Gibson accidentally creates DoS tool

ShieldsUp ripe for malicious use

  • alert
  • submit to reddit

Choosing a cloud hosting partner with confidence

Techno hypemeister Steve Gibson, who clamored for headlines some months back with a dramatic prediction that the misuse of Win-XP's raw sockets would destabilize the entire Internet, has made his own inadvertent contribution to the malicious hackers' tool chest.

Gibson's Web site is littered with hyped-up bells and whistles to mystify the unsophisticated technophile, most of which are harmless; but one of his little magicians' props can be misused to launch a denial of service attack, a security researcher has discovered.

It turns out that his port scanner, ShieldsUp, can easily be directed at arbitrary IP addresses while returning the scan results to the initial user. Thus the tool would become an effective proxy for performing anonymous port scans. Even better, if such an attack were scripted, it would be possible to tie up a Web site with a torrent of Gibson's mighty NanoProbes.

The ShieldsUp flaw was mentioned briefly during a recent Blackhat session regarding the secure development of Web applications by researcher 'Thor' from HammerOfGod.com.

How it works

The problem here is a weak method of determining the ShieldsUp user's IP, which Gibson alludes to in his instructions. "If your IP address is incorrectly determined the wrong machine will be mistakenly tested," he warns. [Gibson's emphasis]

So it's clear that Stevarino can foresee the problem; he just doesn't care enough, or know enough, to fix it properly.

"Gibson has chosen to use a simple hidden tag in the client-side HTML code to identify the IP address that is passed to the scanning engine. Though the client's IP address is hashed, it is trivial to alter the value of the hidden tag in order to request that a different IP address be scanned. The true IP address is never checked in the HTTP header during the scan, and ShieldsUp happily scans the other box while returning the result set into browser of the box the called for the scan," HammerOfGod member 'Magni' says.

But it gets better. Gibson's finger-in-the-dike solution is a little download called "IP Agent" which will ensure that ShieldsUp gets your IP right. Ironically, this little toy makes it even easier to misuse the scanning service.

"We can easily bypass the need to crack the hash by simply using the 'IP Agent' supplied by Gibson....the IP Agent now supports multiple client IP addresses. One simply needs to bind arbitrary IP addresses to a local interface, and perform a scan request. In this case, ShieldsUp presents friendly command buttons listing the IP addresses bound to the local interfaces, and allows you to select any one that you want scanned. Again, no other checking is done, and SheildsUp will scan whatever IP address you ask it to, and report the results into your own browser," Magni observes.

Furthermore, "multiple post requests can be easily scripted to perform scans against a site in attempts to perform a denial of service attack against a host. In these cases, with sufficient requests generated, one could ask grc.com to attack another site, and it will comply."

The IP Agent doesn't even need to be hacked. It will accommodate malicious users straight out of the box.

"One would have hoped that instead of spending so much time expounding on the theoretical denial of service capabilities of Raw Sockets, [Gibson would have used] that time to properly develop his own application in order to prevent the same. In order to prevent the malicious use of Gibson's site to attack our systems, we have blocked Gibson's subnet at the border."

We found this exploit preposterously easy to execute, so perhaps you should do the same. ®

Internet Security Threat Report 2014

More from The Register

next story
FYI: OS X Yosemite's Spotlight tells Apple EVERYTHING you're looking for
It's on by default – didn't you read the small print?
Russian hackers exploit 'Sandworm' bug 'to spy on NATO, EU PCs'
Fix imminent from Microsoft for Vista, Server 2008, other stuff
Edward who? GCHQ boss dodges Snowden topic during last speech
UK spies would rather 'walk' than do 'mass surveillance'
Microsoft pulls another dodgy patch
Redmond makes a hash of hashing add-on
'LulzSec leader Aush0k' found to be naughty boy not worthy of jail
15 months home detention leaves egg on feds' faces as they grab for more power
China is ALREADY spying on Apple iCloud users, claims watchdog
Attack harvests users' info at iPhone 6 launch
Carders punch holes through Staples
Investigation launched into East Coast stores
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
Three 1TB solid state scorchers up for grabs
Big SSDs can be expensive but think big and think free because you could be the lucky winner of one of three 1TB Samsung SSD 840 EVO drives that we’re giving away worth over £300 apiece.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.