Feeds

Mobiles forced to send premium-rate texts in new attack

Hacker hijacks SMS error message flaw

Security for virtualized datacentres

Cybercrooks may be able to force mobiles to send premium-rate SMS messages or prevent them from receiving messages due to security weaknesses in mobile telecoms standards.

The weakness involves the handling of messages directed towards SIM Application Toolkits, applications preloaded onto SIM cards by mobile operators. The applications can be used for functions such as displaying available credit or checking voicemail, as well as handling value-added services, such as micro-payments.

SIM Toolkits receive commands via specially formatted and digitally signed SMS messages. These messages are processed without appearing in a user's inbox and without triggering any other form of alert. Some mobiles may wake from a sleeping state on receipt of such messages but that is about all that's likely to happen.

The encryption scheme deployed is robust but problems might arise because error messages are automatically sent out if a command cannot be executed. The SIM Toolkit service message can be configured so that responses are made via SMS to a sender's number or to the operator's message centre. This creates two possible attack scenarios.

In the first case, an attacker might use an SMS spoofing service to force the dispatch of an error message to a premium-rate number, potentially ringing up fraudulent charges against the account of a targeted phone owner in the process.

Attackers can't control the content of the automatic error responses, a potential stumbling block when it comes to signing up people up for these services simply because they've sent a message, but it's easy to imagine this tactic will be effective enough times to make it potentially workable. A premium-rate number is restricted to signing up people to its services only in response to properly formatted requests rather than an any old message.

In the second case, an SIM Toolkit error message is sent to the operator's message centre, and this is interpreted as a message delivery failure. Operators usually attempt to resend the undelivered message: creating an error loop that prevents the delivery of legitimate SMS messages to a user's handset until a bogus SIM Toolkit message times out, typically after 24 hours or so. Because of this, sending a series of bogus SIM Toolkit messages creates a means of running an SMS DoS attack.

Independent security researcher Bogdan Alecu gave a presentation explaining the security shortcoming, and demonstrating how it might be exploited, at a recent DeepSec security conference in Vienna, Austria.

Alecu tested the attack against phones from Samsung, Nokia, HTC, RIM and Apple. Only phones from Nokia have the option to ask users before confirming the dispatch of an SIM Toolkit response. However the the option "Confirm SIM Service Actions" is usually disabled by default. Operators could mitigate the attack by filtering SIM Toolkit messages and whitelisting numbers that are allowed to send them. However Alecu said he is yet to encounter an operator that applies such controls, even after testing the attack on mobile operators in Romania, Bulgaria, Austria, Germany and France, IDG reports.

The vulnerability was reported by Alecu to the Computer Emergency Response Team and a vulnerability number has been allocated but there are no details on when a fix might be produced. Alecu said that the issue is more easily addressed by filtering by operators than by trying to update millions of handsets anyway. ®

Secure remote control for conventional and virtual desktops

More from The Register

next story
NASTY SSL 3.0 vuln to be revealed soon – sources (Update: It's POODLE)
So nasty no one's even whispering until patch is out
Russian hackers exploit 'Sandworm' bug 'to spy on NATO, EU PCs'
Fix imminent from Microsoft for Vista, Server 2008, other stuff
'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
Forget passwords, let's use SELFIES, says Obama's cyber tsar
Michael Daniel wants to kill passwords dead
FBI boss: We don't want a backdoor, we want the front door to phones
Claims it's what the Founding Fathers would have wanted – catching killers and pedos
Kill off SSL 3.0 NOW: HTTPS savaged by vicious POODLE
Pull it out ASAP, it is SWISS CHEESE
Facebook slurps 'paste sites' for STOLEN passwords, sprinkles on hash and salt
Zuck's ad empire DOESN'T see details in plain text. Phew!
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 cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
Win a year’s supply of chocolate
There is no techie angle to this competition so we're not going to pretend there is, but everyone loves chocolate so who cares.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Intelligent flash storage arrays
Tegile Intelligent Storage Arrays with IntelliFlash helps IT boost storage utilization and effciency while delivering unmatched storage savings and performance.