A high severity authentication bypass vulnerability that resides in ES-File Explorer due to insecure FTP activity let remote attackers gain access to all your files saved in your Android phone.
ES File Explorer is a local file system manager used by more than 500 million users worldwide with many features including accessing the stored files, differentiates the file type, and access the systems files such as apps.
Other than the features listed above, ES file explorer includes interesting future such as gives access to the files system over the network with the help of FTP service using .ftp.ESFtpShortcut by start the FTP over the phone.
Basically, ES-File explorer provide an option to set a master password for users to secure the file access and prevent to access from any application.
Master-password feature in the ES File Explorer File Manager application 4.2.0.1.3 for Android can be bypassed using this authentication bypass vulnerability, and the attacker starts the FTP and accesses the complete file system remotely even if the user set the master password.
Bhavesh Thakur, Security researcher exclusively report to GBHackers on Security says ” To obtain FTP service attacker need to invoke that malicious activity which was responsible to start FTP server on the phone. If things goes well within 2 minutes FTP service starts and an attacker can get complete access to the storage of the victim.”
The attacker can use any malicious apps to obtain the FTP URL and access all files of the local storage from the remote location.
Bhavesh initially used the following activity manager Command to start .ftp.ESFtpShortcut activity which can be performed by an attacker remotely via a malicious application.
am start -n com.estrongs.android.pop/.ftp.ESFtpShortcut
Once its started, device will give you the output below.
Intent { cmp=com.estrongs.android.pop/.ftp.ESFtpShortcut }
shell@j7elte:/ $
At the same time, FTP URL will be created and displayed On mobile notification panel.
“Attacker can simply load that URL to any browser and can access all content of local storage including images, camera, downloads, etc.”
“Please never trust application which provides multiple services. ES file explorer could cause it’s end-user a complete information disclosure of private data”, Bhavesh Thakur told GBHackers on Security.
Its worth mentioned here that ES-File Explorer was removed from play Store after one month of this finding along with the allegation of click fraud.
Bhavesh reported this vulnerability to the ES team and the bug was fixed in v4.2.0.1.4 and the CVE-2019–11380 has assigned.
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