Blackphone super-secure communications app had serious flaw

A vulnerability in the bundled encrypted messaging app would have allowed attackers to execute malicious code on the device

The SilentText secure messaging application bundled with Blackphone had a serious vulnerability that would have allowed attackers to decrypt messages, read contact information, gather location data and even execute malicious code on the phone.

The bug, which was fixed before it was disclosed publicly Tuesday, shows that even devices built with security and privacy in mind can have serious flaws that compromise their defenses.

Blackphone is a high-end smartphone that runs a modified and locked-down version of Android called PrivatOS. It comes preloaded with apps for end-to-end encrypted text messaging, audio calling and video conferencing, as well as secure online storage.

The phone is manufactured by Switzerland-based SGP Technologies, a joint venture between Silent Circle, a provider of encrypted communications services and Spanish phone manufacturer GeeksPhone.

The vulnerability in SilentText, one of the apps bundled with Blackphone, was discovered by Mark Dowd, founder of Australian security consultancy firm Azimuth Security.

"While exploring my recently purchased BlackPhone, I discovered that the messaging application contains a serious memory corruption vulnerability that can be triggered remotely by an attacker," Dowd said in a blog post that contains the technical details of the bug. "If exploited successfully, this flaw could be used to gain remote arbitrary code execution on the target's handset."

The malicious code would execute in the context of the SilentText app and would inherit its privileges. This means the attacker could decrypt text messages, gather location information, read the phone's contacts and write to the external storage, Dowd said.

If the attacker also had knowledge of an Android privilege escalation exploit that affects PrivatOS, he could use it after exploiting the SilentText vulnerability to gain root or kernel access on the device. This would give him complete control over the phone.

The only knowledge an attacker would have needed to exploit the SilentText vulnerability was the target's Silent Circle ID or phone number.

"This issue is now patched by both Silent Circle and Blackphone in the respective App Stores / Product updates," Dowd said.

Blackphone users can update to the latest firmware version following the instructions on the product's support site.

This is not the first vulnerability discovered in Blackphone, but is likely one of the most serious ones found to date. Silent Circle and SGP Technologies run vulnerability reward programs for their respective products through the Bugcrowd platform. Statistics on the Bugcrowd site show that 25 issues have been found and rewarded so far in Blackphone and 37 in the Silent Circle apps and services.

Join the Good Gear Guide newsletter!

Error: Please check your email address.

Tags patchesSilentCircleAzimuth Securitysecuritymobile securityExploits / vulnerabilitiesprivacySGP TechnologiesGeeksphone

Our Back to Business guide highlights the best products for you to boost your productivity at home, on the road, at the office, or in the classroom.

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Lucian Constantin

IDG News Service
Show Comments

Cool Tech

Crucial Ballistix Elite 32GB Kit (4 x 8GB) DDR4-3000 UDIMM

Learn more >

Gadgets & Things

Lexar® Professional 1000x microSDHC™/microSDXC™ UHS-II cards

Learn more >

Family Friendly

Lexar® JumpDrive® S57 USB 3.0 flash drive 

Learn more >

Stocking Stuffer

Plox Star Wars Death Star Levitating Bluetooth Speaker

Learn more >

Christmas Gift Guide

Click for more ›

Most Popular Reviews

Latest News Articles

Resources

GGG Evaluation Team

Kathy Cassidy

STYLISTIC Q702

First impression on unpacking the Q702 test unit was the solid feel and clean, minimalist styling.

Anthony Grifoni

STYLISTIC Q572

For work use, Microsoft Word and Excel programs pre-installed on the device are adequate for preparing short documents.

Steph Mundell

LIFEBOOK UH574

The Fujitsu LifeBook UH574 allowed for great mobility without being obnoxiously heavy or clunky. Its twelve hours of battery life did not disappoint.

Andrew Mitsi

STYLISTIC Q702

The screen was particularly good. It is bright and visible from most angles, however heat is an issue, particularly around the Windows button on the front, and on the back where the battery housing is located.

Simon Harriott

STYLISTIC Q702

My first impression after unboxing the Q702 is that it is a nice looking unit. Styling is somewhat minimalist but very effective. The tablet part, once detached, has a nice weight, and no buttons or switches are located in awkward or intrusive positions.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?