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Android provides capabilities for an app to output or logging information and obtain log output. Application Applications can send information to log output using the android.util.Log class. To obtain log output, application applications can execute the logcat command.

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To log output

The android.util.Log class allows a number of possibilities:

Example:

Log.v("method", Login.TAG + ", account=" + str1);
Log.v("method", Login.TAG + ", password=" + str2);

To obtain log output

Declare READ_LOGS permission in the manifest file so that an app can read log output:

AndroidManifest.xml:

<uses-permission android:name="android.permission.READ_LOGS"/>

Call logcat from an application:

Process mProc = Runtime.getRuntime().exec(
    new String[]{"logcat", "-d", "method:V *:S$Bc`W^(B)"});

BufferedReader mReader = new BufferedReader(
    new InputStreamReader(proc.getInputStream()));

Prior to Android 4.0, any application with READ_LOGS permission could obtain all the other applicationapplications' s log output. After Android 4.1, the specification of {[READ_LOGS}} permission has been changed. Even applications with READ_LOGS permission cannot obtain log output from other applicationapplications.

By However, by connecting an Android device to a PC, however, log output from other application applications can be obtained.

Therefore application should , it is important that applications do not send sensitive information to log output.

Noncompliant Code Example

Facebook SDK for Android contained the following code which sends Facebook access token tokens to log output in plain text format.

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Source: http://blog.parse.com/2012/04/10/discovering-a-major-security-hole-in-facebooks-android-sdk/

Noncompliant Code Example

Here is another example. Weathernews Touch for Android sent a user's location data to the log output as follows:

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If a user is using Android OS 4.0 or before, other application applications with READ_LOGS permission can obtain the user's location information without declaring ACCESS_FINE_LOCATION permission in the manifest file.

Compliant Solution

An example Example code of obtaining log output correctly is as follows:

final StringBuilder slog = new StringBuilder();

try {
  Process mLogcatProc;
  mLogcatProc = Runtime.getRuntime().exec(new String[]
      {"logcat", "-d", "LoginAsyncTask:I APIClient:I method:V *:S" });

  BufferedReader reader = new BufferedReader(new InputStreamReader(
      mLogcatProc.getInputStream()));

  String line;
  String separator = System.getProperty("line.separator");

  while ((line = reader.readLine()) != null) {
    slog.append(line);
    slog.append(separator);
  }
  Toast.makeText(this, "Obtained log information", Toast.LENGTH_SHORT).show();

} catch (IOException e) {
  // handle error
}

TextView tView = (TextView) findViewById(R.id.logView);
tView.setText(slog);

Applicability

Applications should make sure that they do not send sensitive info information to log output. If the app includes 3rd a third party library, the developer should make sure that the library does not send sensitive information to log output. One common solution is for an application to declare and use a custom log class, so that log output is automatically turned on/off based on Debug/Release. Developers can use ProGuard to delete specific method callcalls. This assumes that the method contains no side effects.

Related Vulnerabilities

• Facebook SDK for Android: http://readwrite.com/2012/04/10/what-developers-and-users-can#awesm=~o9iqZAMlUPshPu
• JVN#23328321 Puella Magi Madoka Magica iP for Android vulnerable to information disclosure
• JVN#86040029 Weathernews Touch for Android stores location information in the system log file
• JVN#33159152 Loctouch for Android information management vulnerability
• JVN#56923652 Monaca Debugger for Android information management vulnerability

Related Guidelines