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[liberationtech] Fwd: Android apps used by millions vulnerable to password, e-mail theft

Yishay Mor yishaym at gmail.com
Mon Oct 22 09:00:30 PDT 2012


Any comments on this?
********** Researchers uncover faulty encryption in apps available in
Google's Play Market.

by Dan Goodin <http://arstechnica.com/author/dan-goodin/> - Oct 22 2012,
5:27am
 ** **
** **
By exploiting inadequate SSL protections in an anti-virus app, researchers
were able to force it to download a malicious virus signature.
 Fahl et al.<http://www.dcsec.uni-hannover.de/index.php?eID=tx_nawsecuredl&u=0&file=uploads/tx_tkpublikationen/p50-fahl.pdf&t=1350750207&hash=88db8d7a2ba3c298f8d359f45c76f5fdb28d0ba6>
** **

Android applications downloaded by as many as 185 million users can expose
end users' online banking and social networking credentials, e-mail and
instant-messaging contents because the programs use inadequate encryption
protections, computer scientists have found.

The researchers identified 41 applications in Google's Play
Market<https://play.google.com/>that leaked sensitive data as it
traveled between handsets running the Ice
Cream Sandwich version of Android and webservers for banks and other online
services. By connecting the devices to a local area network that used a
variety of well-known exploits, some of them available
online<http://www.thoughtcrime.org/software/sslstrip/>,
the scientists were able to defeat the secure sockets layer and transport
layer security protocols implemented by the apps. Their research
paper<http://www.dcsec.uni-hannover.de/index.php?eID=tx_nawsecuredl&u=0&file=uploads/tx_tkpublikationen/p50-fahl.pdf&t=1350750207&hash=88db8d7a2ba3c298f8d359f45c76f5fdb28d0ba6>didn't
identify the programs, except to say they have been downloaded from
39.5 million and 185 million times, based on Google statistics.

"We could gather bank account information, payment credentials for PayPal,
American Express and others," the researchers, from Germany's Leibniz
University of Hannover and Philipps University of Marburg, wrote.
"Furthermore, Facebook, email and cloud storage credentials and messages
were leaked, access to IP cameras was gained and control channels for apps
and remote servers could be subverted." Other exposed data included the
contents of e-mails and instant messages.

A Google spokesman declined to comment. There was no evidence any of the
vulnerable apps were developed by Google employees, although the
researchers said there are steps Google engineers could take to better
ensure Android apps implement the encryption more securely.

The findings underscore the fragility of the SSL and TLS protocols, which
together form the basis for virtually all encryption between websites and
end users. While the technology itself is generally considered secure, its
protection can be undermined when certificate authorities fail to secure
their infrastructure<http://www.theregister.co.uk/2011/08/30/fraudulent_google_cert_update/>or
websites
don't take proper
precautions<http://arstechnica.com/business/2012/04/90-of-popular-ssl-sites-vulnerable-to-exploits-researchers-find/>.
The paper, presented at this week's Computer and Communications
Security<http://sigsac.org/ccs/CCS2012/>conference, exposes yet
another point of failure, which is poor
implementation by app developers.

"All things said, it's generally good research that should make developers
more aware of these basic security deficiencies that shouldn't have made it
through any respectable QA process," Jon Oberheide, CTO of mobile firm Duo
Security, told Ars. "Needless to say, security isn't top of mind of most
mobile developers."

The scientists began their research by downloading 13,500 free apps from
Google Play and subjecting them to a "static analysis." Those tests checked
whether the SSL implementations of the apps were potentially vulnerable to
"man-in-the-middle" exploits, in which attackers are able to monitor or
tamper with communications flowing over public Wi-Fi hotspots or other
unsecured networks. The results identified 1,074 apps, or eight percent of
the sample, that contained "SSL specific code that either accepts all
certificates or all hostnames for a certificate and thus are potentially
vulnerable to MITM attacks."

>From the list of the 1,074 potentially vulnerable apps, the researchers
picked 100 of them to subject to a manual audit that connected them to a
network that used an SSL proxy to test whether the SSL implemented in the
devices could be defeated. In some cases, the apps accepted SSL
certificates that were signed by the researchers rather than a valid
certificate authority. In others, the accepted certificates authorized a
domain name other than the one the app was accessing. In still other cases,
the apps were defeated by attacks including
SSLstrip<http://www.theregister.co.uk/2009/02/19/ssl_busting_demo/>,
which researcher Moxie Marlinspike demonstrated in 2009. Some apps also
accepted certificates signed by authorities that are no longer valid. (It
appears the Android operating system gives end users a means to manually
disable various CAs.)

Example of vulnerabilities included:

   - An anti-virus app that accepted invalid certificates when validating
   the connection supplying new malware signatures. By exploiting that trust,
   the researchers were able to feed the app their own malicious signature.
   - An app with an install base of 1 million to 5 million users that was
   billed as a "simple and secure" way to upload and download cloud-based data
   that exposed login credentials. The leakage was the result of a "broken SSL
   channel."
   - A client app for a popular Web 2.0 site with up to 1 million users,
   which appears to be offered by a third-party developer. It leaked Facebook
   and Google credentials when logging in to those sites.
   - A "very popular cross-platform messaging service" with an install base
   of 10 million to 50 million users exposed telephone numbers from the
   address book.

While the researchers didn't identify the vulnerable apps, descriptions
such as a "generic online banking app" suggest that most if not all of them
were offered by third-party developers rather than the websites or services
they connected to. Readers who are concerned their apps are vulnerable
should start their inquiry by looking at those that are developed by
outside firms.
Locking down Android

The paper lists a variety of ways SSL protection can be improved on the
Android platform. One is for the type of static analysis they performed to
be done at the time a user is installing an app. Another is to use a
technique known as certificate pinning, which makes it much harder for an
app or browser to accept fraudulent certificates like the ones used in the
study. The researchers also recommended Google engineers develop new ways
for Android to make it clear when the connection provided by various apps
is encrypted and when it's not. Google may be equipping Android phones with
their own malware
scanner<http://arstechnica.com/gadgets/2012/10/google-play-may-get-its-own-built-in-virus-scanner/>,
recent reports indicate.

The paper made no attempt to measure the security provided by apps
available for Apple's competing iOS platform. One possible reason the
researchers focused on Android apps exclusively is that the openness of the
Google platform made it easier to perform static analysis. That, in turn,
made it possible to zero in on the apps with SSL implementations that
exposed sensitive user data. It would be interesting to see the results of
a similar analysis performed on the 13,000 most popular iPhone apps.
 ** **
Reader comments
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