Software Engineering Institute

According to a Zimperium zLabs blog post, Android's Stagefright engine contains multiple vulnerabilities, including several integer overflows, allowing a remote attacker to access files or possibly execute code on the device. This vulnerability may at least partially affect all versions of Android starting from 2.2 (Froyo) and prior to 5.1.1_r9 (Lollipop).

An attacker with a victim's cell phone number may send maliciously crafted multimedia messages (MMS) which may be improperly parsed by the Stagefright tool. Other attack vectors include client-side (web browsers, downloads, email), physically adjacent (NFC, Bluetooth, VCards), physical (SD cards, USB on-the-go, USB Media Transfer Protocol and Picture Transfer Protocol), Gallery, and possibly others not yet identified.

According to Ars Technica, "successful exploits at the very least provide direct access to a phone's audio and camera feeds and to the external storage ... many older phones grant elevated system privileges to Stagefright code, a design that could allow attackers access to many more device resources."

Zimperium has released an update on 2015-09-09 to their previous information on these vulnerabilities, including a proof of concept code, patches, a video demoing the exploit and an Android app that detects the vulnerability.

The vulnerabilities include:
1.\tCVE-2015-1538, P0006, Google Stagefright ‘stsc’ MP4 Atom Integer Overflow Remote Code Execution
2.\tCVE-2015-1538, P0004, Google Stagefright 𠆌tts’ MP4 Atom Integer Overflow Remote Code Execution
3.\tCVE-2015-1538, P0004, Google Stagefright ‘stts’ MP4 Atom Integer Overflow Remote Code Execution
4.\tCVE-2015-1538, P0004, Google Stagefright ‘stss’ MP4 Atom Integer Overflow Remote Code Execution
5.\tCVE-2015-1539, P0007, Google Stagefright 𠆎sds’ MP4 Atom Integer Underflow Remote Code Execution
6.\tCVE-2015-3827, P0008, Google Stagefright 𠆌ovr’ MP4 Atom Integer Underflow Remote Code Execution
7.\tCVE-2015-3826, P0009, Google Stagefright 3GPP Metadata Buffer Overread
8.\tCVE-2015-3828, P0010, Google Stagefright 3GPP Integer Underflow Remote Code Execution
9.\tCVE-2015-3824, P0011, Google Stagefright ‘tx3g’ MP4 Atom Integer Overflow Remote Code Execution
10.\tCVE-2015-3829, P0012, Google Stagefright 𠆌ovr’ MP4 Atom Integer Overflow Remote Code Execution

Zimperium has also released a second round of Stagefright vulnerabilities on 2015-10-01. Processing specially crafted MP3 or MP4 files can lead to arbitrary code execution.

1. CVE-2015-6602, Google libutils vulnerability
2. CVE-2015-6610, Google libstagefright vulnerability

A remote attacker may be able to execute code on the Android device.

Apply an update

The Android Open Source Project (AOSP) has released Android 5.1.1_r9 to address the original issues. The newer "Stagefright 2.0" issues have been addressed in Nexus build LMY48K or later, or Android Marshmallow with Security Patch Level of November 1, 2015 or later.

Partial fixes are available for Nexus (now being pushed over the air), Samsung and HTC phones (AT&T has pushed this over the air).

In the US, cell phone carriers largely control the updating process. The update may or may not be available for your phone. Contact your cell phone carrier or manufacturer for update information.

Note that in the aftermath of the original disclosure, it has been determined that the original patches fail to completely resolve the original vulnerability. CVE-2015-3864 has been assigned by Google to identify the issue identified in a blog post by Exodus Intelligence, and updates are to be available as previously described.

Alternatively, the MMS attack vector of this vulnerability may be mitigated by the following workarounds:

Block all text messages from unknown senders

Blocking all text messages from unknown senders in your default text message handling app may mitigate this issue.

Turn off "Auto Retrieve" for multimedia messages

If your default text messaging app does not allow blocking of senders, you may also disable the auto retrieve feature for multimedia messages. This may prevent the autoloading of MMS content into Stagefright.