Tuesday, August 17, 2010

FLIRT progress

Last semester, my goal was to get a working FLIRT implemetnation up and running. However, with it being my most intense semester to date, I didn't get as far as I wanted Most of the work involved code fixes and some crude code fixes to the Red Plait (rpat) pattern generator.
Really though, rpat needed a full rewrite to be truly useful in my project. While I could have maintained in its original C form, I really would rather have had a highly functionalized version using STL data structures. As of commit e719d6ddba27bf1fa4d1ace18d3426a356d19fa5, this is done. Example output:
[mcmaster@gespenst bin]$ ./uvobj2pat.dynamic --input=../obj2pat/main_d.o
5589E583EC18E8........C1E81F84C07426C744240C........C74424085800 2B E01B 004B :011F _Z14initProgConfigv ^0007 _Z21initFLIRTSharedConfigv ^0016 ^0026 ^0032 uv_err_ret_handler ^0039 g_config ^0040 5589E583EC18........FFC1E81F84C07426........5E0100........085800........240406000000C7
5589E55383EC24C745E8FFFFFFFFC745EC00000000C745F000000000C745F4FF FF F3C5 0349 :01A4 _Z6uvmainiPPc ^0024 _Z13UVDGetVersionv ^0037 strcmp ^0045 _Z13UVDGetVersionv ^005B ^0060 printf ^0065 stdout ^006D fflush ^0072 _Z7UVDInitv ^0081 ^0091 ^009D uv_err_ret_handler ^00A7 g_config ^00B8 ^00C8 ^00D4 uv_err_ret_handler ^00DE _Z14initProgConfigv ^00ED ^00FD ^0109 uv_err_ret_handler ^0127 _ZN9UVDConfig9parseMainEiPKPc ^0138 ^0148 ^0154 uv_err_ret_handler ^0173 ^017F printf_debug_level ^0186 g_flirt ^018B _ZN8UVDFLIRT8getFLIRTEPPS_ ^0199 ^019E puts ^01AF g_flirt ^01BB ^01CB ^01D7 uv_err_ret_handler ^01E1 g_uvd ^01ED ^01FD ^0209 uv_err_ret_handler ^0213 g_uvd ^0222 ^0232 ^023E uv_err_ret_handler ^0248 g_uvd ^0261 ^0271 ^027D uv_err_ret_handler ^0290 _ZNKSt6vectorISsSaISsEE5emptyEv ^029B ^02A0 puts ^02A5 _Z7UVDHelpv ^02AD ^02BD ^02C8 uv_err_ret_handler ^02DD ^02E2 puts ^02EF _Z9UVDDeinitv ^02FE ^030E ^031A uv_err_ret_handler ^0324 ^0334 ^033F uv_err_ret_handler 5589E553........45E8FFFFFFFFC745EC00000000C745........00C745F4FFFFFFFFE8FC........C3E82DFEFFFF895C2404890424E8FCFFFFFF........C0........E8........89C3E80C........5C........2404C7042460000000E8FC........00000000890424E8FCFFFFFF........FFC1E81F84C07429........57010000C744........0000C744240406000000C70424........E8FCFFFFFFE99D020000A100........45EC837DEC007529........57010000C744........0000C744240406000000C7........FFFFE8FCFFFFFFE966020000........FFC1E81F84C07429........57010000C744240881000000C744240406000
5589E583E4F083EC20C7442404........C7042405000000E8........8B450C 3C F345 005C :04ED main ^000D ^0019 printf_debug_level ^002B _Z6uvmainiPPc ^0037 ^0043 printf_debug_level 5589E583E4F083EC20C744........0000C70424050000........FFFF8B450C894424........890424E8FCFFFFFF8944241CC74424044B010000C7
Which seems consistent with the assembly:
4ed: 55 push %ebp
4ee: 89 e5 mov %esp,%ebp
4f0: 83 e4 f0 and $0xfffffff0,%esp
4f3: 83 ec 20 sub $0x20,%esp
4f6: c7 44 24 04 3e 01 00 movl $0x13e,0x4(%esp)
4fd: 00
4fe: c7 04 24 05 00 00 00 movl $0x5,(%esp)
505: e8 fc ff ff ff call 506
50a: 8b 45 0c mov 0xc(%ebp),%eax
50d: 89 44 24 04 mov %eax,0x4(%esp)
511: 8b 45 08 mov 0x8(%ebp),%eax
514: 89 04 24 mov %eax,(%esp)
517: e8 fc ff ff ff call 518
51c: 89 44 24 1c mov %eax,0x1c(%esp)
520: c7 44 24 04 4b 01 00 movl $0x14b,0x4(%esp)
527: 00
528: c7 04 24 05 00 00 00 movl $0x5,(%esp)
52f: e8 fc ff ff ff call 530
534: 83 7c 24 1c 00 cmpl $0x0,0x1c(%esp)
539: 79 07 jns 542
53b: b8 01 00 00 00 mov $0x1,%eax
540: eb 05 jmp 547
542: b8 00 00 00 00 mov $0x0,%eax
547: c9 leave
548: c3 ret

However, the correctness of this won't be known until I actually try processing it. This version should be much easier to maintain and be more stable. There are some assorted points to fix, but it was definitely a step in the right direction. Next steps will be to implement pattern generation for libuvudec based disassembling and verify FLAIR's makesig produces the same output and/or is valid for input to pat2sig. One of the challenges I will of course face is how to support all of the architectures. I'm thinking the best way will be for any arch IDA does not support, I'll put a different magic number at the start of the file and add a new architecture field
Part of the reason I got working on this again is someone pointed out to me someone posted the .sig binary format here. I was hoping to do this last semester, but mostly due to time constraints, didn't get to it. With the format out there now, it will be much easier to implement a pat2sig equivalent and the matching loader.
Finally, I made a quick stab at a Qt GUI:
All it does is display the function list. I was trying to figure out how to get the window to resize to fit the whole screen but needs more work. I don't have a lot of GUI experience, so there will be a learning curve to get things decent. Hopefully though, if this project becomes popular, it shouldn't be too hard for someone to design something better and swap it out. The major issue that became readily apparent is the engine is currently designed for one shot analysis. It cannot respond to annotations. Thus, some sort of analysis event system will have to be implemented. This will be important for plugins as well as they may need to respond to various engine events if they want to do more than just respond to keystrokes. In the near future for the GUI, I'd like to:
-Get the window to resize correctly
-Display a dead listing
-Ability to double click on functions and have that location appear in the dead listing
-Write comments
-Load and save a workspace (I briefly toyed with this)
-Load FLIRT signatures. This may be sooner than later as I'm currently writing uvpat2sig which will mean I'll have at least most of first revision signature engine up.

No comments:

Post a Comment