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README.md
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policybuffer.js
policybuffer.js
 
 

README.md

policybuffer.js

policybuffer.js is a JavaScript debugger extension for WinDbg that disassembles Policy buffer programs used by the Chromium sandbox. Those programs are used to evaluate policy decision.

Usage

Run .scriptload policybuffer.js to load the script. You can invoke the disassembler feature with !disasspolicy <addr>.

Examples

  • Dumping the File System policy of Firefox:
0:017> !disasspolicy 0x00000131`d2142208
!OP_NUMBER_AND_MATCH<Param1, 0x1>
!OP_WSTRING_MATCH<Param0, "\??\", Length(0x4), Offset(0x0), CASE_SENSITIVE>
OP_ACTION<ASK_BROKER>

!OP_NUMBER_AND_MATCH<Param1, 0x1>
OP_WSTRING_MATCH<Param0, "~", Length(0x1), Offset(0xffffffff), CASE_SENSITIVE>
OP_ACTION<ASK_BROKER>

OP_WSTRING_MATCH<Param0, "\??\C:\Users\over\AppData\LocalLow\Mozilla\Temp-{8aca3358-7266-42d0-a521-805394768d86}\", Length(0x57), Offset(0x0), CASE_INSENSITIVE>
OP_ACTION<ASK_BROKER>

!OP_NUMBER_AND_MATCH<Param2, 0x5fedff56>
OP_NUMBER_MATCH<Param3, UINT32_TYPE(0x1)>
OP_WSTRING_MATCH<Param0, "\??\C:\Users\over\AppData\Local\Microsoft\Windows\Fonts\", Length(0x38), Offset(0x0), CASE_INSENSITIVE>
OP_ACTION<ASK_BROKER>

!OP_NUMBER_AND_MATCH<Param2, 0x5fedff56>
OP_NUMBER_MATCH<Param3, UINT32_TYPE(0x1)>
OP_WSTRING_MATCH<Param0, "\??\C:\work\firefox-66.0a1.en-US.win64\firefox\", Length(0x2f), Offset(0x0), CASE_INSENSITIVE>
OP_ACTION<ASK_BROKER>

!OP_NUMBER_AND_MATCH<Param2, 0x5fedff56>
OP_NUMBER_MATCH<Param3, UINT32_TYPE(0x1)>
OP_WSTRING_MATCH<Param0, "\??\C:\Users\over\AppData\Roaming\Mozilla\Firefox\Profiles\rbo6kdsb.default-nightly\chrome\", Length(0x5b), Offset(0x0), CASE_INSENSITIVE>
OP_ACTION<ASK_BROKER>

!OP_NUMBER_AND_MATCH<Param2, 0x5fedff56>
OP_NUMBER_MATCH<Param3, UINT32_TYPE(0x1)>
OP_WSTRING_MATCH<Param0, "\??\C:\Users\over\AppData\Roaming\Mozilla\Firefox\Profiles\rbo6kdsb.default-nightly\extensions\", Length(0x5f), Offset(0x0), CASE_INSENSITIVE>
OP_ACTION<ASK_BROKER>

!OP_NUMBER_AND_MATCH<Param2, 0x5fedff56>
OP_NUMBER_MATCH<Param3, UINT32_TYPE(0x1)>
OP_WSTRING_MATCH<Param0, "\??\C:\Users\over\AppData\Roaming\Mozilla\SystemExtensionsDev\", Length(0x3e), Offset(0x0), CASE_INSENSITIVE>
OP_ACTION<ASK_BROKER>

!OP_NUMBER_AND_MATCH<Param2, 0x5fedff56>
OP_NUMBER_MATCH<Param3, UINT32_TYPE(0x1)>
OP_WSTRING_MATCH<Param0, "\??\C:\Users\over\AppData\Roaming\Mozilla\Extensions\", Length(0x35), Offset(0x0), CASE_INSENSITIVE>
OP_ACTION<ASK_BROKER>

OP_WSTRING_MATCH<Param0, "\??\pipe\chrome.", Length(0x10), Offset(0x0), CASE_INSENSITIVE>
OP_ACTION<ASK_BROKER>

OP_WSTRING_MATCH<Param0, "\??\pipe\gecko-crash-server-pipe.", Length(0x21), Offset(0x0), CASE_INSENSITIVE>
OP_ACTION<ASK_BROKER>

@$disasspolicy(0x00000131`d2142208)