How can I view the differences between two DLLs?

Question

Is there a way to view the difference between two binary DLL files? I have PDBs for both.

Ideally I'd like to see:

• What functions have been added
• What functions have been removed
• What functions have been modified (with a diff of the disassembly)
• What other entries (static variables, resources, etc) have been added/removed/modified

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Note: this is different from this question as I am dealing with native DLLs.

Answer 1

If you want to compare executable files, you have a couple of alternatives:

• Bindiff: it's a commercial extension for the commercial disassembler IDA Pro. It's a de-facto tool for reverse engineering. According to the vendor description, it allows you to:
  • Identify identical and similar functions in different binaries
  • Port function names, anterior and posterior comment lines, standard comments and local names from one disassembly to the other
  • Detect & highlight changes between two variants of the same function

http://www.zynamics.com/bindiff.html

• You still have a free alternative: PatchDiff. As Bindiff, it's also a plugin for IDA Pro. According to the developer, Patchdiff can perform the following tasks:
  • Display the list of identical functions
  • Display the list of matched functions
  • Display the list of unmatched functions (with the CRC)
  • Display a flow graph for identical and matched functions

http://cgi.tenablesecurity.com/tenable/patchdiff.php

Answer 2

A "low tech" approach (no disassembly) would be to use DUMPBIN /ALL (or another switch, depending on what exactly you want to know) on the DLLs and do a text compare on the result.