Crash Dump Analysis Patterns (Part 194)

Whereas some false positives can be considered soft debugger bugs false negatives can have more severe impact on software behavior analysis especially in malware analysis. We name this pattern Debugger Omission. Typical example here is current .imgscan command which according to documentation should by default scan virtual process space for MZ/PE signatures. Unfortunately it doesn’t detect such signatures in resource pages (we haven’t checked stack regions yet):

0000000000fd0000 image base

.rsrc name
6430 virtual size
4000 virtual address
6600 size of raw data
1600 file pointer to raw data
0 file pointer to relocation table
0 file pointer to line numbers
0 number of relocations
0 number of line numbers
40000040 flags
Initialized Data
(no align specified)
Read Only

0:000> .imgscan /r 00000000`00fd4000 L200

0:000> s -[l2]sa 00000000`00fd4000 l200
00000000`00fd40b0  "MZ"
00000000`00fd40fd  "!This program cannot be run in D"
00000000`00fd411d  "OS mode."
00000000`00fd4188  "Rich"
00000000`00fd4198  "PE"

0:000> !dh 00000000`00fd40b0

File Type: DLL
14C machine (i386)
3 number of sections
time date stamp Fri Jan 18 21:27:25 2013

0 file pointer to symbol table
0 number of symbols
E0 size of optional header
2102 characteristics
32 bit word machine

Another other analysis scenarios found will be added to this pattern. Milder version of it includes !analyze -v that shows us a breakpoint instead of an exception violation from a parallel thread.

- Dmitry Vostokov @ + -

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