Feeds

Unicode bug restyled as DoS tool

Big Poop drops a big one on IIS

  • alert
  • submit to reddit

Internet Security Threat Report 2014

The infamous Unicode IIS Web server exploit can also be used as a denial of service attack tool.

Gray hat hacker Big Poop has published a site on the Internet explaining how the Unicode bug, which permits the execution of commands on a Web server, can be used to tie up system resources so that legitimate users can't access a site - a classic DoS attack technique.

Mark Read, a security consultant at MIS Corporate Defence Solutions, who has reviewed Big Poop's site, said the exploit works by running up a number of processes on a server that do not terminate, such as comp.exe (which will wait indefinitely until the filenames of files to be compared are entered).

"Since the program doesn't terminate, IIS keeps the connection open assuming that something is going to be passed back to the browser," said Reid. "After so many connections though, IIS will stop any further connections in an attempt to stop the server from crying itself to sleep."

The exploit would give a s'kiddie a good chance of bringing a Web server exposed to the Unicode bug down to its knees using a web browser and a simple three part procedure (which we won't publish here). Restarting a machine will, at least, interrupt (if not curtail) the denial of service, but the issue still gives serious cause for concern, particular given how easy it is to exploit.

As Big Poop said: "If you still don't get it [the exploit] give up hackin' cause it ain't going to get any simpler, maybe relax and play the classic old school game chuckie egg, you know it makes sense.

"I don't think you are going to find an easier DOS attack for a while, well not until WindowsXP comes out anyway," he added.

Some security experts said the Unicode DoS attack, which can be automated through the use of scripts, is "more efficient" that more familiar network-based DDoS attacks, which commonly rely on installing Trojan horse programs on a range of compromised "zombie" clients. Under the control of a cracker, these zombies then fire off a batch of spurious commands against target servers with the intention of making sites unavailable.

Despite the possibility of mounting denial of service attacks on vulnerable servers using the Unicode bug, MIS's Read still reckons s'kiddies are still more likely to deface a site than mount a denial of service attack against it.

"This is a DOS attack, but to be perfectly honest if the sys admin hasn't applied the patch for the Unicode vulnerability then it goes without saying that the server is going to be wide open," he said. ®

External Links

Patch to fix Unicode exploit
CERT advisory

Related Stories

Yet another IIS exploit reported
Intel hacker talks to The Reg
MS hacked once, twice, three, FOUR times

Top 5 reasons to deploy VMware with Tegile

More from The Register

next story
Regin: The super-spyware the security industry has been silent about
NSA fingered as likely source of complex malware family
Why did it take antivirus giants YEARS to drill into super-scary Regin? Symantec responds...
FYI this isn't just going to target Windows, Linux and OS X fans
Privacy bods offer GOV SPY VICTIMS a FREE SPYWARE SNIFFER
Looks for gov malware that evades most antivirus
Home Office: Fancy flogging us some SECRET SPY GEAR?
If you do, tell NOBODY what it's for or how it works
HACKERS can DELETE SURVEILLANCE DVRS remotely – report
Hikvision devices wide open to hacking, claim securobods
'Regin': The 'New Stuxnet' spook-grade SOFTWARE WEAPON described
'A degree of technical competence rarely seen'
Syrian Electronic Army in news site 'hack' POP-UP MAYHEM
Gigya redirect exploit blamed for pop-rageous ploy
Astro-boffins start opening universe simulation data
Got a supercomputer? Want to simulate a universe? Here you go
prev story

Whitepapers

10 ways wire data helps conquer IT complexity
IT teams can automatically detect problems across the IT environment, spot data theft, select unique pieces of transaction payloads to send to a data source, and more.
Getting started with customer-focused identity management
Learn why identity is a fundamental requirement to digital growth, and how without it there is no way to identify and engage customers in a meaningful way.
How to determine if cloud backup is right for your servers
Two key factors, technical feasibility and TCO economics, that backup and IT operations managers should consider when assessing cloud backup.
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 and trust: The backbone of doing business over the internet
Explores the current state of website security and the contributions Symantec is making to help organizations protect critical data and build trust with customers.