IMSI Catchers and Mobile Security

6.3 Data Collection App source code snippet
The Data Collection App was initially written by graduate students involved in researching
cell towers under Professor Nadia Heninger’s guidance. In the spring 2015 semester, this author
worked on debugging the app to allow stable data collection and adding functionality to the user
interface, in order to embark on the first round of cell tower data collection in Philadelphia (see
Section 4.5).
Below is a snippet from the DataCollectionActivity.class file of the Data Collection
App, which manages the core function that collects information about cell towers in the vicinity
whenever the mobile phone detects a change in signal strength.
// Check that min required time has elapsed since last data entry
timeElapsed = System.nanoTime() - lastCollectedTime;
if (timeElapsed >= delayNanoSec) {
// Logs time since last data entry
Log.d(COLLECTION, "Proceed - " +
(float) timeElapsed/1000000000 +
" sec since last entry");
// Check that data collection count doesn't exceed maximum before collecting
if (current_count_coll_json_obj < MAX_COLLECTIONS_JSON_OBJECTS) {
StringBuffer display_string = new StringBuffer();
List neighborList = telephonyManager
.getNeighboringCellInfo();
// Check that NeighboringCellInfo list is not empty
if (neighborList != null) {
// Report the number of NeighboringCellInfo objects received
Log.d(COLLECTION, String.valueOf(neighborList.size()) +
" neighboring cells found.");
// Process each NeighboringCellInfo packet
for (int i = 0; i < neighborList.size(); i++) {
NeighboringCellInfo neighboringCellInfo =
(NeighboringCellInfo) neighborList.get(i);
// Print neighboring cell information to screen
display_string.append("CID: "
+ neighboringCellInfo.getCid()
+ " LAC: "
+ neighboringCellInfo.getLac()
+ " PSC: "
+ neighboringCellInfo.getPsc()
+ " RSSI: "
+ neighboringCellInfo.getRssi()
+ "\n\n");
// Record transaction information to cell JSONObject
JSONObject entry = new JSONObject();
try {
// Add cell tower signal information to cell JSONObject
entry.put("cid",
neighboringCellInfo.getCid());
entry.put("lac",
neighboringCellInfo.getLac());
entry.put("psc",
neighboringCellInfo.getPsc());
entry.put("rssi",
neighboringCellInfo.getRssi());
// Add latitude longitude information to cell JSONObject
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