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The Case of the Unexplained…

The Case of the Unexplained…. Mark Russinovich Technical Fellow Windows Azure. WCA-B306. Outline. Introduction Sluggish Performance Error Messages Application Crashes Blue Screens. Case of the Unexplained…. This is the 2013 version of the “case of the unexplained” talk series

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The Case of the Unexplained…

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  1. The Case of the Unexplained… Mark Russinovich Technical Fellow Windows Azure WCA-B306

  2. Outline Introduction Sluggish Performance Error Messages Application Crashes Blue Screens

  3. Case of the Unexplained… • This is the 2013 version of the “case of the unexplained” talk series • Previous versions covered different cases • Can view webcast on Sysinternals->Mark’s webcasts • Based on real case studies • Some of these have been written up on my blog

  4. Troubleshooting • Most applications do a poor job of reporting unexpected errors • Locked, missing or corrupt files • Missing or corrupt registry data • Permissions problems • Errors manifest in several different ways • Misleading error messages • Crashes or hangs

  5. Purpose of Talk • Show you how to solve these classes of problems by peering beneath the surface • Interpreting process, file and registry activity • Interpreting call stacks • You’ll learn tools and techniques to help you solve seemingly unsolvable problems

  6. Tools We’ll Use • Sysinternals: www.microsoft.com/technet/sysinternals (\\redmond\files\SYSINTERNALS\LBI\Latest) • Process Explorer – process/thread viewer • Process Monitor – file/registry/process/thread tracing • Procdump – process memory dumper • Autoruns – displays all autostart locations • SigCheck – shows file version information • PsExec – execute processes remotely or in the system account • TcpView – shows TCP/IP endpoints • Strings – dumps printable strings in any file • Zoomit – presentation tool I’m using • Microsoft downloads: • Debugging Tools for Windows: Windbg application and kernel debugger: www.microsoft.com/whdc/devtools/debugging (//dbg)

  7. The Sysinternals Administrator’s Reference • The official guide to the Sysinternals tools • Covers every tool, every feature, with tips • Written by markruss and aaronmar • Full chapters on the major tools: • Process Explorer • Process Monitor • Autoruns • Other chapters by tool group • Security, process, AD, desktop, …

  8. Outline Sluggish Performance Error Messages Application Crashes Blue Screens

  9. The Case of the Sluggish Explorer • Explorer was very slow to display the contents of local files • Captured a Process Monitor trace

  10. Process Monitor • Process Monitor is a real-time file, registry, process and thread monitor • When in doubt, run Process Monitor! • It will often show you the cause for error messages • It many times tells you what is causing sluggish performance

  11. Process Monitor Enhancements: Bookmarks • Bookmarking enables you to save markers in the trace: • Use F6 to find the next one, Shift+F6 to search up

  12. The Case of the Sluggish Explorer (Cont) • Noticed numerous references to network path with NAME NOT FOUND:

  13. The Case of the Sluggish Explorer (Cont) • Checked account mapping and saw that home drive was network share: • Confirmed in Process Explorer current directory was the network share:

  14. The Case of the Sluggish Explorer: Solved • Opened command prompt, killed Explorer, and restarted from local directory: no delays • Contacted IT and had them change home directory: problem solved

  15. Process Explorer • Process Explorer is a Task Manager replacement • You can literally replace Task Manager with Options->Replace Task Manager • Hide-when-minimized to always have it handy • Hover the mouse to see a tooltip showing the process consuming the most CPU • Open System Information graph to see CPU usage history • Graphs are time stamped with hover showing biggest consumer at point in time • Also includes other activity such as I/O, kernel memory limits

  16. Process Explorer v15: GPU Monitoring and Windows 8 • Captures GPU utilization and memory usage • System-wide • Per-Process

  17. Process Explorer v15.2 • Process timelines • Autostart locations

  18. Process Explorer v15.3 • Process view heat map columns • Bit-matching dump files • Disk counters fixed for Windows 8

  19. The Case of the Spiking ICQ Process • System was sluggish • Opened Process Explorer and saw Instant messaging application consuming CPU:

  20. Processes and Threads • A process represents an instance of a running program • Address space • Resources (e.g., open handles) • Security profile (token) • A thread is an execution context within a process • Unit of scheduling (threads run, processes don’t run) • All threads in a process share the same per-process address space • The System process is the default home for kernel mode system threads • Functions in OS and some drivers that need to run as real threads • E.g., need to run concurrently with other system activity, wait on timers, perform background “housekeeping” work • Other host processes: svchost, Iexplore, mmc, dllhost

  21. Viewing Threads • Task Manager doesn’t show thread details within a process • Process Explorer does on “Threads” tab • Displays thread details such as ID, CPU usage, start time, state, priority • Start address is where the thread began running (not where it is now) • Click Module to get details on module containing thread start address

  22. Thread Start Functions and Symbol Information • Process Explorer can map the addresses within a module to the names of functions • This can help identify which component within a process is responsible for CPU usage • Configure Process Explorer’s symbol engine: • Download the latest Debugging Tools for Windows from Microsoft (free) • Use dbghelp.dll from the Debugging Tools • Point at the Microsoft public symbol server (or internal symbol server if you have access)

  23. The Case of the Spiking ICQ Process (Cont) • Looked at threads tab • Start address of spiking threads were generic:

  24. Viewing Call Stacks • Click Stack on the Threads tab to view a thread’s call stack • Note that start address on Threads tab is different than first function shown in stack • This is because all threads created by Windows programs start in a library function in Kernel32.dll which calls the programmed start address

  25. The Case of the Spiking ICQ Process (Cont) • Looked at thread stack and saw video DLL:

  26. The Case of the Spiking ICQ Process (Cont) • Opened DLL view and saw that each time issue occurred, four video DLLs were loaded: • Noted that DLLs were not loaded on program startup • Opened Add/Remove programs, but saw no software from Viscom

  27. Autoruns • Shows every place in the system that can be configured to run something at boot & logon • Standard Run keys and Startup folders • Shell, userinit • Services and drivers • Tasks • Winlogonnotifica`tions • Explorer and IE addins (toolbars, Browser Helper Objects, …) • More and ever growing… • Each startup category has its own tab and all items display on the Everything tab • Startup name, image description, company and path

  28. Identifying Malware Autostarts • Zoom-in on add-ons (including malware) by selecting these filter options: • Verify Code Signatures • Hide Microsoft Entries • Select an item to see more in the lower window • Online search unknown images • Double-click on an item to look at where its configured in the Registry or file system • Has other features: • Can also show empty locations (informational only) • Includes compare functionality • Includes equivalent command-line version, Autorunsc.exe

  29. The Case of the Spiking ICQ Process: Solved • Opened Autoruns and disabled all Viscom DLLs: • Problem solved

  30. The Case of the Company 15-Minute Logons • Logons were taking 5-15 minutes across a company for one OS image • The other OS image had normal logon time • Execs started to complain • Admins tried everything: • Examined event viewer • Captured Wireshark traces • Checked for malware • Finally, another admin that had seen “Case of the Unexplained” decided to help: • Captured a Process Monitor boot trace

  31. The Case of the Company 15-Minute Logons (Cont) • Looked through process tree and noticed Framepkg taking four minutes: • Command-line showed it was McAfee A/V reinstallation

  32. The Case of the Company 15-Minute Logons: Solved • Question was: why was script reinstalling A/V? • Contacted server admins: • They discovered that Active Directory OU for OS image had GPO • GPO should have been removed from domain after Win7 rollout • Removed GPO: problem solved

  33. Outline Sluggish Performance Error Messages Application Crashes Blue Screens

  34. The Case of the File in Use Error • Tried deleting PowerPoint deck I had been editing, but got an error: • No sign of PowerPoint running,not even in Task Manager’s applications tab

  35. The Case of the File in Use Error: Solved • Did a Handle Search in Process Explorer • Found hidden PowerPoint process: • Terminated process: problem solved

  36. The Case of the Mistaken Windows-to-Go • User tried to use the Windows 8 AppStore, but got an error message: • Had installed Windows on a Maxtor SATA 2 disk, but for some reason Windows thought it was a portable USB disk

  37. The Case of the Mistaken Windows-to-Go: Solved • Captured a Process Monitor trace when trying to access the store and scanned the log • Found this reference: • Deleted the PortableOperatingSystem value: problem solved

  38. The Case of the Default Win8 RDP Lockscreen Background • Set Windows 8 lockscreento custom background • When RDP’ing into the system, default lockscreen showed • Needed to find out where default was coming from • Captured a Process monitor trace of locking system and RDP’ing into system

  39. The Case of the Default Win8 RDP Lockscreen Background (Cont) • Set a filter to “Path Begins With .jpg”: Lock RDP

  40. The Case of the Default Win8 RDP Lockscreen Background: Solved • Had to replace system version of lockscreen background • Launched command prompt as system using PsExec: • Copied background over RDP lockscreen file: • Problem solved

  41. Outline Sluggish Performance Error Messages Application Crashes Blue Screens

  42. The Case of the Crashing IE Favorites • IE was crashing every time Favorites was clicked • Ran IE8 without Add-ons • Still Crashed • Upgraded to IE9 • Still Crashed • Ran IE9 without Add-ons • Still Crashed

  43. The Case of the Crashing IE Favorites (Cont) • Used Process Explorer to get the PID of iexplore.exe:

  44. The Case of the Crashing IE Favorites (Cont) • Used ProcDump to capture a unhandled exception (-e) mini dump

  45. The Case of the Crashing IE Favorites (Cont) • Changed to the Exception Context Record (.ecxr) and looked at the stack (k) – looked like it was sorting

  46. The Case of the Crashing IE Favorites (Cont) • Suspected one favorite that had bullets: • Moved all of the Favorites to another folder • Still Crashed

  47. The Case of the Crashing IE Favorites (Cont) • Captured a Process Monitor trace • Set a filter for IE, ‘Action’ is SUCCESS and ‘Path’ contains ‘Favorites’, and Registry

  48. The Case of the Crashing IE Favorites (cont.) • Saw Order REG_BINARY value read from HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MenuOrder\Favorites:

  49. The Case of the Crashing IE Favorites: Solved • Used “Jump to” context menu to open Regedit • Renamed ‘Order’ value to ‘xOrder’ • Restarted IE: problem solved • Moved the favorites back • Looked at RegEdit, new ‘Order’ value made

  50. Outline Application Hangs Sluggish Performance Error Messages Blue Screens

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