Crash Dump Analysis Patterns (Part 146)

One way to quickly check for something suspicious in a memory dump is to convert it to a debugger log (for example, stack trace collection) and search for textual strings such as “Waiting for“, “Terminate“, “Stop”, “Mutant“, “Exception“, “Crit“, “MessageBox“, “SuspendCount“, etc. The vocabulary, of course, is OS dependent, can have false positives, and can change over time. We name this pattern Problem Vocabulary. It is similar to Vocabulary Index software trace analysis pattern.

For example, recently in a complete memory dump involving lots of ALPC wait chains with potential inter-process deadlock we found the following thread having long waiting time (exceeding ALPC threads waiting times) pointing to a process object to examine further:

THREAD fffffa801338b950  Cid 02a0.7498  Teb: 000007fffffd8000 Win32Thread: 0000000000000000 WAIT: (UserRequest) UserMode Non-Alertable
    fffffa8012a39b30  ProcessObject
Not impersonating
DeviceMap                 fffff8a000008a70
Owning Process            fffffa800a31d040       Image:         smss.exe
Attached Process          N/A            Image:         N/A
Wait Start TickCount      9752080        Ticks: 5334204 (0:23:09:06.937)
Context Switch Count      38            
UserTime                  00:00:00.000
KernelTime                00:00:00.000
Win32 Start Address ntdll!TppWorkerThread (0×000000007722fbc0)
Stack Init fffff88020259db0 Current fffff88020259900
Base fffff8802025a000 Limit fffff88020254000 Call 0
Priority 11 BasePriority 11 UnusualBoost 0 ForegroundBoost 0 IoPriority 2 PagePriority 5
Kernel stack not resident.
Child-SP          RetAddr           Call Site
fffff880`20259940 fffff800`01693f92 nt!KiSwapContext+0×7a
fffff880`20259a80 fffff800`016967af nt!KiCommitThreadWait+0×1d2
fffff880`20259b10 fffff800`01984b2e nt!KeWaitForSingleObject+0×19f
fffff880`20259bb0 fffff800`0168df93 nt!NtWaitForSingleObject+0xde
fffff880`20259c20 00000000`7726135a nt!KiSystemServiceCopyEnd+0×13 (TrapFrame @ fffff880`20259c20)
00000000`0048f648 00000000`48026517 ntdll!NtWaitForSingleObject+0xa
00000000`0048f650 00000000`480269c4 smss!SmpTerminateCSR+0xa3
00000000`0048f6a0 00000000`48023670 smss!SmpStopCsr+0×44
00000000`0048f6d0 00000000`77288137 smss!SmpApiCallback+0×338
00000000`0048f900 00000000`7722feff ntdll! ?? ::FNODOBFM::`string’+0×1f718
00000000`0048f990 00000000`77274a00 ntdll!TppWorkerThread+0×3f8
00000000`0048fc90 00000000`00000000 ntdll!RtlUserThreadStart+0×25

In that process we could see a blocking module and recommended to contact its vendor: 

- Dmitry Vostokov @ + -

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