Task manager not reactivated after closing SEB

SEB 2.0
  • Phil Butcher

    Phil Butcher - 2014-03-18

    Another finding from our trial, affecting 4 out of 15 users. After leaving SEB (we provided an exit link) they were left with laptops where the only option brought up by Ctrl-Alt-Del was 'Cancel'.

  • Daniel Schneider

    On those laptops try to start SEB and quit it again. Check if task manager etc. is back in the security screen (Ctrl-Alt-Del). Try this without starting an exam.

    Are these the same laptops where the options (task manager etc.) were not switched off when using a settings password and a .seb file for starting an exam? Were these laptops also running Windows 8/8.1?

    Switching the options on/off in the Windows Security Screen requires SEB to send a command to the SEB Windows Service running in background. The service changes key/values in the Registry to disable the options. When quitting SEB, again the SEB Service gets a command to reset the Registry key/values. On machines where disabling the options doesn't work in some cases probably also re-enabling them won't work.

    As by now I guess this problem happens on some machines with Windows 8/8.1. In our testing this problem didn't happen until now, so it's really hard to debug this. Please send me the SebClient.log files from machines where either case happened (this is written into the current user's AppData\Local\SafeExamBrowser directory.

  • Phil Butcher

    Phil Butcher - 2014-03-19

    At least 2 of the 4 machines were running Windows 7.

    On one of those machines restarting SEB and exiting again cleared the problem.
    On another machine this didn't work and we had to run RegistryEnableAllBlueScreenButtons.bat.

    I'll get the log files.

  • Phil Butcher

    Phil Butcher - 2014-03-21

    I have obtained one of the log files from a Windows 7 laptop. The history goes as follows.
    1) SEB installed
    2) SEB run for a practice exam. Task manager et al come up after exit. No problems.
    3) Repeat (2) several times.
    4) SEB run for the pilot exam. Task manager et al not enabled after exit instead just have 'cancel' as if still in SEB. I should add that the .seb file used for this pilot was the same as that used in (2).
    5) Multiple attempts at reproducing (4) have not resulted in any failure.

    I attach the log file in the hope that there's something there for you.

  • Jarle Presttun

    Jarle Presttun - 2014-03-25

    A client in another part of the country tested out SEB 2.0 RC4, tested it, uninstalled it and installed 1.9.1
    He contacted me and told me taskmanager was disabled and ctrl+alt+del only had cancel.
    I suggested it probably was the problem as described in this task and sent him RegistryEnableAllBlueScreenButtons.bat.
    The problem here is that this didn't work, so he is currently reinstalling win 7 (!!!). Quite weird, as this bat file has helped me a couple of times and it seems others in the forum has been helped too.
    I don't have much, but he sent me a screenshot of console after running the bat-file. For him it fails on utilman.exe. Not sure if that is important.

    Last edit: Jarle Presttun 2014-03-25
  • Daniel Schneider

    I guess that person didn't execute RegistryEnableAllBlueScreenButtons.bat properly. In another post I explained how it has to be used:

    If it still doesn't work, you can use the batch script RegistryEnableAllBlueScreenButtons.bat which gets installed together with SEB in the subdirectory SebWindowsToolkit. For this to work you need to run it from the same user account with which you tested SEB, but make that user administrator temporarily. Then you need to right click on this .bat and choose "Run as administrator". The script should re-enable all buttons in that screen.

    I know, this is a bit complicated and unfortunately it's not yet described in the documentation of the current version how to use RegistryEnableAllBlueScreenButtons.bat properly. I am working on that and also on a FAQ.

    In future we will provide better means how to reset the registry values easier. This has first priority and we want to have it implemented in the final 2.0 release.

  • Phil Butcher

    Phil Butcher - 2014-03-26

    Here's a bit better news. Other posts in this forum will tell you that in our pilot our users have been trying to break the SEB WindowsRC4+Moodle combination. That was our brief to them. And they found Ctrl-F, Ctrl-K, Right-click and then started creating links and launching pop-up windows to external sites. As detailed in my other posts we traced these to the tinyMCE editor in Moodle and we've now blocked Ctrl-F, Ctrl-K and Right-click.

    And now we've done this we can't reproduce the problem of Task Manager not being reactivated. Of course we'll keep an eye out for it reappearing but for now we're happy to let this issue lapse.

  • Daniel Schneider

    I found out something interesting today while further investigating why it seemed that sometimes in my development VM some of the functions in the Windows Security Screen (invoked by Ctrl-Alt-Del) were not switched off while having SEB running or didn't get switched on again after leaving SEB: It seems that it takes a few moments for the functions to disappear or reappear. So when I pressed Ctrl-Alt-Del immediately after SEB was started or quit, some or all functions where not yet switched off/on. If waiting a few seconds, they were set as they should be. Probably it takes some moments for the changes to take effect after the SEB Windows Service gets the command to change those settings.

    We're nevertheless working now on improving this process, especially also for the case that someone resets the machine before SEB could reset these settings in Windows Registry.

  • Daniel Schneider

    In the just released RC5, we have completely re-engineered SEB Windows Service with improved stability for setting and resetting options in the Windows Security Screen (invoked by Ctrl-Alt-Del) like Task Manager. In case of a SEB crash or enforced reset of the machine, now the options are reset to the values which were active before SEB was used when rebooting the computer or uninstalling SEB.

    We hope that this solves most if not all problems with disabling and reactivating the task manager and the other options in the Windows Security Screen.

    Please test SEB 2.0 Release Candidate 5 very thoroughly, especially regarding this feature. It's theoretically still possible that setting/resetting these options would fail on some machines because of Windows weirdnesses, strange Group Policies, virus scanners/security software etc., but we hope this new implementation should be much more stable than the old one.


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