The researcher successfully exploited the vulnerability on his Samsung Galaxy S4 Mini running version 4.2.2.0200 of Stock Android Email App, he explained that the bug appears to affect all older versions of the Stock Android Email App, though devices running 4.2.2.0400 and newer versions are not affected.

The effect of an attack can be really annoying for a user because the easiest way to restore a normal situation it  to remove the malicious email from the Stock Android Email App. Consider also that this operation represents only a temporary solution because the attacker can send many malicious emails to the bitter end.

“Since the application crashes immediately, to remove the malicious email is a little bit tricky. The easiest and straightforward way to remove it is by using other email client (or via web) from the inbox at the email server. Another way is by disabling the internet connexion (Airplane mode) before launching the email reader, and then you can remove the offending email,” he added.

The expert explained that the flaw is caused by the incorrect handling of the Content-Disposition header, he discovered that to exploit the flaw it is sufficient to send an email with a malformed Content-Disposition header and cause the crash of the application.

The malformed header that doesn’t include parameters and cause the crash is:

Content-Disposition:

Email Android Google 4.2.2.0200 crasher
=======================================
Author:  Hector Marco <[email protected]>
Website: http://hmarco.org

$ ./crash_Android_Google_email_4.2.2.0200.py -s [email protected] -r [email protected]
[+] Sending crafted message to: [email protected]
[+] Malicious email successfully sent.

Pierluigi Paganini

(Security Affairs –  Google Gmail App mobile)