Feeds

Personal firewalls are ‘futile’

Harry Homeowner at risk

  • alert
  • submit to reddit

Choosing a cloud hosting partner with confidence

Security researchers have highlighted a potential shortcoming with personal firewall products.

To alert users of the presence of a Trojan or privacy threatening program running on their systems, personal firewalls have been adapted so they monitor and block outbound traffic (as well as blocking inbound network traffic).

If a malicious program becomes active a user will be alerted and the application will be blocked by a personal firewall (unless a user is daft enough to agree that it should be able to access the Internet, of course).

This would normally stop a Trojan sending out data (which might be your passwords) disguised as HTTP traffic on port 80.

However if a malicious program modifies a DLL used by Internet Explorer to make an outbound connections to port 80 on its behalf then this protection is bypassed.

Security researcher Robin Keir, has developed a proof-of-concept tool, called FireHole, which illustrates how the trick can fool personal firewalls (such as Zone Alarm, Norton Personal Firewall and Black Ice Defender).

The technique (along with other similar tricks) relies on a rogue program getting onto a user's system and executing in the first place, as Keir points out, but his work dispels the notion that a personal firewall on its own will stop Trojans in their tracks.

"If you can't stop it [a Trojan executing] then it is game over - the rogue program has your computer completely under it's control," said Keir.

Keir's findings are backed up by another security researcher, Bob Sundling, who said "the added protection provided by outbound filtering is entirely illusory" after he developed a program called TooLeaky to illustrate his point.

Eric Chien, chief researcher at Symantec's Anti-Virus Research Centre, said the technique "doesn't make personal firewalls useless" but rather illustrates the point that there is no such thing as complete protection.

"Combined with AV, the average home user is relatively safe," said Chien, who added that the technique has yet to be used in anger by either virus writers or hackers.

"In general if such a thing were created, we would add detection for it in antivirus," he added. ®

Tips to stay protected from Trojans


  • Keep antivirus programs up-to-date

  • Lock down email clients with the correct security zone settings

  • Avoid opening attachments that might contain executable content

  • Consider restricting the ports that your web browser and other commonly used applications can talk on

  • Remember WinXP's built-in firewall does not attempt to manage or restrict outbound connections at all, though it does block port scanning and the like



External Links

How to bypass your personal firewall outbound detection (by Robin Keir)
Personal firewalls are pants (by Bob Sundling)

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.