Challenge LAB-0001

Read a Samsung reset trail

Tell a factory reset from a SIM region change in a recovery log, link the two recovery files by run code, and say what a missing entry does not prove.

Starter 20 to 30 minutesAndroid7 questions, 75 pointsAlways open, self-paced
Start the questionsRead the article first

The task

A Samsung phone writes a log of every recovery run. A factory reset leaves a recognisable entry, linked to a second file by a two-letter code. You will read the five runs in the article's Figure 1 and answer what they show, no more and no less.

All challenge data is synthetic or comes from the Lab's published articles. No account is needed, nothing you type here leaves your browser except each answer you check, and the optional form if you send it.

What you need

Tools (all free)

  • A plain text editor
  • A spreadsheet or Python (to read the CSV files)

Any tool that reads text will do. You do not need the Lab's own software or an account.

Questions

Each answer is checked when you press Check answer, and you see the result straight away. A wrong answer costs nothing, and you may try again. A hint lowers the points you can earn for that question: 1, 2 and 3 points for hints 1, 2 and 3, and a correct answer always earns at least 1 point. Checking needs JavaScript; reading does not.

  1. Question 1 of 710 points

    Which file holds the lines that show /data, /cache and /metadata being formatted?

    See Figure 2 of the article.

    Need a hint?

    Three hints, in order. Each one lowers the points you can earn for this question.

    Hint 1 costs 1 point

    Two files make up the recovery log. One lists the runs, the other lists the work each run did.

    Hint 2 costs 2 points

    Figure 2 shows lines that start with the run code in square brackets, such as [Je][S].

    Hint 3 costs 3 points

    It sits beside history in the same folder, and its name starts with the word extra.

  2. Question 2 of 710 points

    In Figure 1, what is the run code of the second factory reset?

    Answers are not case sensitive.

    Need a hint?

    Three hints, in order. Each one lowers the points you can earn for this question.

    Hint 1 costs 1 point

    A factory reset is a --wipe_data entry with MasterClearConfirm as its reason.

    Hint 2 costs 2 points

    There are two of them among the five runs. Take the later one.

    Hint 3 costs 3 points

    The code is two letters, the first one capital.

  3. Question 3 of 710 points

    How many of the five runs in Figure 1 are SIM region changes?

    Need a hint?

    Three hints, in order. Each one lowers the points you can earn for this question.

    Hint 1 costs 1 point

    A region change is logged with --just_exit.

    Hint 2 costs 2 points

    Count the entries whose reason contains [SIMBasedChangeCSC].

    Hint 3 costs 3 points

    Five runs, two of them factory resets.

  4. Question 4 of 710 points

    The first SIM region change in Figure 1 (run eW) switched the phone to which region code? Give the three letters.

    Need a hint?

    Three hints, in order. Each one lowers the points you can earn for this question.

    Hint 1 costs 1 point

    Read the reason line of that entry.

    Hint 2 costs 2 points

    The reason shows the old code, an arrow, then the new code.

    Hint 3 costs 3 points

    The old code is XAA. The new code is the carrier named in the article as T-Mobile US.

  5. Question 5 of 710 points

    By the recovery clock as printed, how many minutes passed between the first factory reset (Je) and the second (Mt)? Round to the nearest minute.

    Need a hint?

    Three hints, in order. Each one lowers the points you can earn for this question.

    Hint 1 costs 1 point

    Both clocks are on 1970/01/01, so only the time of day matters.

    Hint 2 costs 2 points

    Subtract 01:37:21 from 05:02:53.

    Hint 3 costs 3 points

    The gap is 3 hours, 25 minutes and 32 seconds.

  6. Question 6 of 715 points

    Select every statement that is true of a SIM region change entry in this trail.

    Select all that apply.

    Need a hint?

    Three hints, in order. Each one lowers the points you can earn for this question.

    Hint 1 costs 1 point

    Three of the five statements are true. Compare them with the section on SIM region changes.

    Hint 2 costs 2 points

    It is a run through recovery. Nothing is formatted, so extra_history has no lines for its code.

    Hint 3 costs 3 points

    True: it uses --just_exit, its reason contains [SIMBasedChangeCSC], and it can still be dated because it sits in the same log.

  7. Question 7 of 710 points

    A phone's recovery history holds no wipe entry. What may you say?

    Need a hint?

    Three hints, in order. Each one lowers the points you can earn for this question.

    Hint 1 costs 1 point

    Think about entries that roll off, volumes that can be formatted, and files that were not collected.

    Hint 2 costs 2 points

    See the section What this does not prove.

    Hint 3 costs 3 points

    A missing entry is not an answer either way.

You have finished: what you should have learned

  • Two files, one code. A wipe entry in history has format lines under the same code in extra_history; a SIM region change has none.
  • A region change is a run through recovery, not a reset. Count it separately.
  • The recovery clock can read 1970, so do not date entries from it directly. Use the requested time where the entry has one, and label any estimate as an estimate.
  • A missing entry shows only that this file, read this way, holds nothing. It does not show that no reset happened.
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