The suspected ‘backdoor encryption’
saga has continued to trail WhatsApp, a company of Facebook, reports ITRealms.
This is coming as some online
security professionals refused to buy into the excuses of Facebook and
WhatsApp, that the ‘Backdoor' is really a feature for ensuring messages are not
lost in certain situations.
ITRealms recalls that despite WhatsApp denial of having
backdoor for decrypting messages, the much WhatsApp’s much touted end-to-end
encryption capability has become the subject of considerable scrutiny following
a report by The Guardian Friday of a ‘backdoor’ in the messaging service that
apparently allows for encrypted messages to be intercepted and read, according
to DarkReading.
Also, the Guardian’s report was based on a vulnerability
disclosure that Tobias Boelter, a PhD student and computer scientist at the
University of California made a few months ago and precisely on April last year.
Boelter claimed that he had found a serious weakness in the
manner in which the latest version of WhatsApp handles messages that are sent
to a recipient who might have swapped or reset their phone, or might simply
have been offline when the message was sent.
In such situations Boleter said, WhatsApp holds the message
and retransmits it when the recipient comes back online but using a different
encryption key than the one that was originally used to encrypt the message.
This approach gives attackers an opportunity to spoof the
recipient’s phone on the WhatsApps server, use their own public key, and
intercept messages that were intended for the recipient.
The Guardian described Boelter’s discovery as a security
backdoor that governments could use to snoop in on the communications of
targeted and unsuspecting WhatsApp users.
WhatsApp’s practice of creating new encryption keys for
offline users without the knowledge of the sender and then rebroadcasting the
message, effectively allows Facebook to intercept and read the messages of
users communicating with each other under the assumption that their messages
are impenetrable, the paper warned.
In an updated blog post, Boelter Friday expressed uncertainty
over whether the issue he discovered is a bug or a backdoor. “In other words:
Is this flaw put deliberately into the WhatsApp messenger to allow them or the
government to look at targeted messages?” he wrote. “Or is the flaw introduced
through a simple programmer error? Or is it even a useful feature?”
According to Boelter, Facebook showed little interest when
he first reported his discovery to them last April, but recently claimed that
it was not a bug but a feature for ensuring messages got through as intended to
offline users.
In an emailed statement to Dark Reading, a Facebook
spokesperson described The Guardian’s claims as patently false. “The design
decision referenced in the Guardian story prevents millions of messages from
being lost,” the spokesperson said. “In many parts of the world, people
frequently change devices and SIM cards. In these situations, we want to make
sure people's messages are delivered, not lost in transit.”
In addition, WhatsApp has a security notifications option
that people can use if they want to be notified when a contact’s security code
or public encryption key has changed, the WhatsApp spokesman said.
Jon Geater, chief technology officer of Thales e-Security
said the concerns raised by Boelter are not as serious as they might appear.
“Indeed, there is almost no hack here. One might argue that
WhatsApp has elected to provide an insecure default configuration,” Geater said
in a statement. “Users who care about the authorities intercepting their
messages are quite likely to turn on security notifications, and then the
problem is almost entirely diminished,” he said.
Dissidents and those using WhatsApp in repressive countries
might need to take additional precautions like using an out of band method to
ensure that a user has really changed devices, he said.
Chris Perry, COO of Secured Communications says the most
troubling aspect about the whole controversy is the lack of full disclosure by
Facebook WhatsApp.
“When a company builds into its system a failsafe, such as
this feature, there should be full disclosure to their customer base that it
exists and how and why it would be activated,” Perry says in comments to Dark
Reading.
As it is, only the sender is informed of the encryption key
change and that too only if the sender has opted-in to the notification
warning, he says. “There should be a warning notification for both sender and
recipient that is default activated advising when they are no longer in a
secure encrypted environment.”
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