On February 16th at 10:36 GMT, we received a high-priority alert from a customer regarding an issue with the PassFort portal. Specifically, some files were not displaying correctly when opened, with certain PDFs appearing as text. Following a brief investigation, we determined that the root cause of the problem was an incorrect file classification, which was related to a recent update to our file service. We promptly reverted the update, and by 16:19 GMT, the issue was resolved. However, we still needed to remediate all files created during the period between the release of the update and its reversal.
The root cause of the issue has been identified as an update to the file type detection strategy, which introduced a flawed sequence of detection steps. Specifically, the update prioritized classifying files as text/plain before checking for other types of files, leading to incorrect classifications.
The issue concerned files with a very specific structure while our automated and manual tests use generic files that did not cover this specific test case; for this reason automated tests and our QA processes were not able to detect the issue. As a result, we have: