Stagefright (bug)

The underlying attack vector exploits certain integer overflow vulnerabilities in the Android core component called libstagefright, which is a complex software library implemented primarily in C++ as part of the Android Open Source Project (AOSP) and used as a backend engine for playing various multimedia formats such as MP4 files.

The discovered bugs have been provided with multiple Common Vulnerabilities and Exposures (CVE) identifiers, CVE-2015-1538, CVE-2015-1539, CVE-2015-3824, CVE-2015-3826, CVE-2015-3827, CVE-2015-3828, CVE-2015-3829 and CVE-2015-3864 (the latter one has been assigned separately from the others), which are collectively referred to as the Stagefright bug.

In order to exploit the vulnerability one doesn't specifically need an MMS message (which was just an example of using the vulnr for RCE), but any other processing of the specifically crafted media by the vulnerable component is enough, that can be done via the most of applications having to deal with media files but not using own-bundled (which increases size of an app and imposes additional unjustified costs on its developer) pure software (which is slow and not energy efficient) media codecs for that, such as media players/galleries, web browsers (can cause drive-by compromise) and file managers showing thumbnails (can be used for achieving persistence).

History

The Stagefright bug was discovered by Joshua Drake from the Zimperium security firm, and was publicly announced for the first time on July 27, 2015. Prior to the announcement, Drake reported the bug to Google in April 2015, which incorporated a related bugfix into its internal source code repositories two days after the report. In July 2015, Evgeny Legerov, a Moscow-based security researcher, announced that he had found at least two similar heap overflow zero-day vulnerabilities in the Stagefright library, claiming at the same time that the library has been already exploited for a while. Legerov also confirmed that the vulnerabilities he discovered become unexploitable by applying the patches Drake submitted to Google.

The public full disclosure of the Stagefright bug, presented by Drake, took place on August 5, 2015 at the Black Hat USA computer security conference, and on August 7, 2015 at the DEF CON 23 hacker convention. Following the disclosure, on August 5, 2015, Zimperium publicly released the source code of a proof-of-concept exploit, actual patches for the Stagefright library (although the patches were already publicly available since early May 2015 in the AOSP and other open-source repositories), and an Android application called "Stagefright detector" that tests whether an Android device is vulnerable to the Stagefright bug.

On August 13, 2015, another Stagefright vulnerability, CVE-2015-3864, was published by Exodus Intelligence. This vulnerability was not mitigated by existing fixes of already known vulnerabilities. CyanogenMod team published a notice that patches for CVE-2015-3864 have been incorporated in CyanogenMod 12.1 source on August 13, 2015.

On October 1, 2015, Zimperium released details of further vulnerabilities, also known as Stagefright 2.0. This vulnerability affects specially crafted MP3 and MP4 files that execute their payload when played using the Android Media server. The vulnerability has been assigned identifier CVE-2015-6602 and was found in a core Android library called libutils; a component of Android that has existed since Android was first released. Android 1.5 through 5.1 are vulnerable to this new attack and it is estimated that one billion devices are affected.