(Windows 7) Solitaire practical joke

(The note below has been copypasted to the Reverse Engineering for Beginners book.)

This is a joke I did once for my coworkers who played a Solitaire game too much. I was wondering, if it's possible to remove some cards, or maybe add (duplicates).

I opened Solitaire.exe in IDA disassembler, which asked if to download PDB file for it from Microsoft servers. This is usually a rule for many Windows executables and DLLs. At least, PDB has all function names.

Then I tried to find a 52 number in all functions (because this card game uses 52 cards). As it turned out, only 2 functions has it.

The first is:

.text:00000001000393B4 ; __int64 __fastcall SolitaireGame::OnMoveComplete(SolitaireGame *this)
.text:00000001000393B4 ?OnMoveComplete@SolitaireGame@@QEAAHXZ proc near


The second is the function with self-describing name (name pulled from PDB by IDA): InitialDeal():

.text:00000001000365F8 ; void __fastcall SolitaireGame::InitialDeal(SolitaireGame *__hidden this)
.text:00000001000365F8 ?InitialDeal@SolitaireGame@@QEAAXXZ proc near
.text:00000001000365F8 var_58          = byte ptr -58h
.text:00000001000365F8 var_48          = qword ptr -48h
.text:00000001000365F8 var_40          = dword ptr -40h
.text:00000001000365F8 var_3C          = dword ptr -3Ch
.text:00000001000365F8 var_38          = dword ptr -38h
.text:00000001000365F8 var_30          = qword ptr -30h
.text:00000001000365F8 var_28          = xmmword ptr -28h
.text:00000001000365F8 var_18          = byte ptr -18h
.text:00000001000365F8 ; FUNCTION CHUNK AT .text:00000001000A55C2 SIZE 00000018 BYTES
.text:00000001000365F8 ; __unwind { // __CxxFrameHandler3
.text:00000001000365F8                 mov     rax, rsp
.text:00000001000365FB                 push    rdi
.text:00000001000365FC                 push    r12
.text:00000001000365FE                 push    r13
.text:0000000100036600                 sub     rsp, 60h
.text:0000000100036604                 mov     [rsp+78h+var_48], 0FFFFFFFFFFFFFFFEh
.text:000000010003660D                 mov     [rax+8], rbx
.text:0000000100036611                 mov     [rax+10h], rbp
.text:0000000100036615                 mov     [rax+18h], rsi
.text:0000000100036619                 movaps  xmmword ptr [rax-28h], xmm6
.text:000000010003661D                 mov     rsi, rcx
.text:0000000100036620                 xor     edx, edx        ; struct Card *
.text:0000000100036622                 call    ?SetSelectedCard@SolitaireGame@@QEAAXPEAVCard@@@Z ; SolitaireGame::SetSelectedCard(Card *)
.text:0000000100036627                 and     qword ptr [rsi+0F0h], 0
.text:000000010003662F                 mov     rax, cs:?g_pSolitaireGame@@3PEAVSolitaireGame@@EA ; SolitaireGame * g_pSolitaireGame
.text:0000000100036636                 mov     rdx, [rax+48h]
.text:000000010003663A                 cmp     byte ptr [rdx+51h], 0
.text:000000010003663E                 jz      short loc_10003664E
.text:0000000100036640                 xor     r8d, r8d        ; bool
.text:0000000100036643                 mov     dl, 1           ; int
.text:0000000100036645                 lea     ecx, [r8+3]     ; this
.text:0000000100036649                 call    ?PlaySoundProto@GameAudio@@YA_NH_NPEAI@Z ; GameAudio::PlaySoundProto(int,bool,uint *)
.text:000000010003664E loc_10003664E:                          ; CODE XREF: SolitaireGame::InitialDeal(void)+46
.text:000000010003664E                 mov     rbx, [rsi+88h]
.text:0000000100036655                 mov     r8d, 4
.text:000000010003665B                 lea     rdx, aCardstackCreat ; "CardStack::CreateDeck()::uiNumSuits == "...
.text:0000000100036662                 mov     ebp, 10000h
.text:0000000100036667                 mov     ecx, ebp        ; unsigned int
.text:0000000100036669                 call    ?Log@@YAXIPEBGZZ ; Log(uint,ushort const *,...)
.text:000000010003666E                 mov     r8d, 52         ; ---
.text:0000000100036674                 lea     rdx, aCardstackCreat_0 ; "CardStack::CreateDeck()::uiNumCards == "...
.text:000000010003667B                 mov     ecx, ebp        ; unsigned int
.text:000000010003667D                 call    ?Log@@YAXIPEBGZZ ; Log(uint,ushort const *,...)
.text:0000000100036682                 xor     edi, edi

.text:0000000100036684 loc_100036684:                          ; CODE XREF: SolitaireGame::InitialDeal(void)+C0
.text:0000000100036684                 mov     eax, 4EC4EC4Fh
.text:0000000100036689                 mul     edi
.text:000000010003668B                 mov     r8d, edx
.text:000000010003668E                 shr     r8d, 4          ; unsigned int
.text:0000000100036692                 mov     eax, r8d
.text:0000000100036695                 imul    eax, 52         ; ---
.text:0000000100036698                 mov     edx, edi
.text:000000010003669A                 sub     edx, eax        ; unsigned int
.text:000000010003669C                 mov     rcx, [rbx+128h] ; this
.text:00000001000366A3                 call    ?CreateCard@CardTable@@IEAAPEAVCard@@II@Z ; CardTable::CreateCard(uint,uint)
.text:00000001000366A8                 mov     rdx, rax        ; struct Card *
.text:00000001000366AB                 mov     rcx, rbx        ; this
.text:00000001000366AE                 call    ?Push@CardStack@@QEAAXPEAVCard@@@Z ; CardStack::Push(Card *)
.text:00000001000366B3                 inc     edi
.text:00000001000366B5                 cmp     edi, 52         ; ---
.text:00000001000366B8                 jb      short loc_100036684

.text:00000001000366BA                 xor     r8d, r8d        ; bool
.text:00000001000366BD                 xor     edx, edx        ; bool
.text:00000001000366BF                 mov     rcx, rbx        ; this
.text:00000001000366C2                 call    ?Arrange@CardStack@@QEAAX_N0@Z ; CardStack::Arrange(bool,bool)
.text:00000001000366C7                 mov     r13, [rsi+88h]
.text:00000001000366CE                 lea     rdx, aCardstackShuff ; "CardStack::Shuffle()"
.text:00000001000366D5                 mov     ecx, ebp        ; unsigned int
.text:00000001000366D7                 call    ?Log@@YAXIPEBGZZ ; Log(uint,ushort const *,...)
.text:00000001000366DC                 and     [rsp+78h+var_40], 0
.text:00000001000366E1                 and     [rsp+78h+var_3C], 0
.text:00000001000366E6                 mov     [rsp+78h+var_38], 10h
.text:00000001000366EE                 xor     ebx, ebx
.text:00000001000366F0                 mov     [rsp+78h+var_30], rbx


Anyway, we clearly see a loop of 52 iterations. A loop body has calls to CardTable()::CreateCard() and CardStack::Push().

The CardTable::CreateCard() eventually calls Card::Init() with values in 0..51 range, as one of its arguments. This can be easily checked using debugger.

So I tried just to change the 52 (0x34) number to 51 (0x33) in the "cmp edi, 52" instruction at 0x1000366B5 and run it. At first glance, nothing happened, but I noticed that now it's hard to solve the game. I spent almost hour to reach this "position":

Ace of hearts is missing. Perhaps, internally, this card is numbered as 51th (if to number them from zero).

In the other place I found all card names. Maybe names to be used to fetch card graphics from resources?

.data:00000001000B6970 ?CARD_NAME@Card@@2PAPEBGA dq offset aTwoofclubs
.data:00000001000B6970                                         ; "TwoOfClubs"
.data:00000001000B6978                 dq offset aThreeofclubs ; "ThreeOfClubs"
.data:00000001000B6980                 dq offset aFourofclubs  ; "FourOfClubs"
.data:00000001000B6988                 dq offset aFiveofclubs  ; "FiveOfClubs"
.data:00000001000B6990                 dq offset aSixofclubs   ; "SixOfClubs"
.data:00000001000B6998                 dq offset aSevenofclubs ; "SevenOfClubs"
.data:00000001000B69A0                 dq offset aEightofclubs ; "EightOfClubs"
.data:00000001000B69A8                 dq offset aNineofclubs  ; "NineOfClubs"
.data:00000001000B69B0                 dq offset aTenofclubs   ; "TenOfClubs"
.data:00000001000B69B8                 dq offset aJackofclubs  ; "JackOfClubs"
.data:00000001000B69C0                 dq offset aQueenofclubs ; "QueenOfClubs"
.data:00000001000B69C8                 dq offset aKingofclubs  ; "KingOfClubs"
.data:00000001000B69D0                 dq offset aAceofclubs   ; "AceOfClubs"
.data:00000001000B69D8                 dq offset aTwoofdiamonds ; "TwoOfDiamonds"
.data:00000001000B69E0                 dq offset aThreeofdiamond ; "ThreeOfDiamonds"
.data:00000001000B69E8                 dq offset aFourofdiamonds ; "FourOfDiamonds"
.data:00000001000B69F0                 dq offset aFiveofdiamonds ; "FiveOfDiamonds"
.data:00000001000B69F8                 dq offset aSixofdiamonds ; "SixOfDiamonds"
.data:00000001000B6A00                 dq offset aSevenofdiamond ; "SevenOfDiamonds"
.data:00000001000B6A08                 dq offset aEightofdiamond ; "EightOfDiamonds"
.data:00000001000B6A10                 dq offset aNineofdiamonds ; "NineOfDiamonds"
.data:00000001000B6A18                 dq offset aTenofdiamonds ; "TenOfDiamonds"
.data:00000001000B6A20                 dq offset aJackofdiamonds ; "JackOfDiamonds"
.data:00000001000B6A28                 dq offset aQueenofdiamond ; "QueenOfDiamonds"
.data:00000001000B6A30                 dq offset aKingofdiamonds ; "KingOfDiamonds"
.data:00000001000B6A38                 dq offset aAceofdiamonds ; "AceOfDiamonds"
.data:00000001000B6A40                 dq offset aTwoofspades  ; "TwoOfSpades"
.data:00000001000B6A48                 dq offset aThreeofspades ; "ThreeOfSpades"
.data:00000001000B6A50                 dq offset aFourofspades ; "FourOfSpades"
.data:00000001000B6A58                 dq offset aFiveofspades ; "FiveOfSpades"
.data:00000001000B6A60                 dq offset aSixofspades  ; "SixOfSpades"
.data:00000001000B6A68                 dq offset aSevenofspades ; "SevenOfSpades"
.data:00000001000B6A70                 dq offset aEightofspades ; "EightOfSpades"
.data:00000001000B6A78                 dq offset aNineofspades ; "NineOfSpades"
.data:00000001000B6A80                 dq offset aTenofspades  ; "TenOfSpades"
.data:00000001000B6A88                 dq offset aJackofspades ; "JackOfSpades"
.data:00000001000B6A90                 dq offset aQueenofspades ; "QueenOfSpades"
.data:00000001000B6A98                 dq offset aKingofspades ; "KingOfSpades"
.data:00000001000B6AA0                 dq offset aAceofspades  ; "AceOfSpades"
.data:00000001000B6AA8                 dq offset aTwoofhearts  ; "TwoOfHearts"
.data:00000001000B6AB0                 dq offset aThreeofhearts ; "ThreeOfHearts"
.data:00000001000B6AB8                 dq offset aFourofhearts ; "FourOfHearts"
.data:00000001000B6AC0                 dq offset aFiveofhearts ; "FiveOfHearts"
.data:00000001000B6AC8                 dq offset aSixofhearts  ; "SixOfHearts"
.data:00000001000B6AD0                 dq offset aSevenofhearts ; "SevenOfHearts"
.data:00000001000B6AD8                 dq offset aEightofhearts ; "EightOfHearts"
.data:00000001000B6AE0                 dq offset aNineofhearts ; "NineOfHearts"
.data:00000001000B6AE8                 dq offset aTenofhearts  ; "TenOfHearts"
.data:00000001000B6AF0                 dq offset aJackofhearts ; "JackOfHearts"
.data:00000001000B6AF8                 dq offset aQueenofhearts ; "QueenOfHearts"
.data:00000001000B6B00                 dq offset aKingofhearts ; "KingOfHearts"
.data:00000001000B6B08                 dq offset aAceofhearts  ; "AceOfHearts"

.data:00000001000B6B10 ; public: static unsigned short const * near * Card::CARD_HUMAN_NAME
.data:00000001000B6B10 ?CARD_HUMAN_NAME@Card@@2PAPEBGA dq offset a54639Cardnames
.data:00000001000B6B10                                         ; "|54639|CardNames|Two Of Clubs"
.data:00000001000B6B18                 dq offset a64833Cardnames ; "|64833|CardNames|Three Of Clubs"
.data:00000001000B6B20                 dq offset a62984Cardnames ; "|62984|CardNames|Four Of Clubs"
.data:00000001000B6B28                 dq offset a65200Cardnames ; "|65200|CardNames|Five Of Clubs"
.data:00000001000B6B30                 dq offset a52967Cardnames ; "|52967|CardNames|Six Of Clubs"
.data:00000001000B6B38                 dq offset a42781Cardnames ; "|42781|CardNames|Seven Of Clubs"
.data:00000001000B6B40                 dq offset a49217Cardnames ; "|49217|CardNames|Eight Of Clubs"
.data:00000001000B6B48                 dq offset a44682Cardnames ; "|44682|CardNames|Nine Of Clubs"
.data:00000001000B6B50                 dq offset a51853Cardnames ; "|51853|CardNames|Ten Of Clubs"
.data:00000001000B6B58                 dq offset a46368Cardnames ; "|46368|CardNames|Jack Of Clubs"
.data:00000001000B6B60                 dq offset a61344Cardnames ; "|61344|CardNames|Queen Of Clubs"
.data:00000001000B6B68                 dq offset a65017Cardnames ; "|65017|CardNames|King Of Clubs"
.data:00000001000B6B70                 dq offset a57807Cardnames ; "|57807|CardNames|Ace Of Clubs"
.data:00000001000B6B78                 dq offset a48455Cardnames ; "|48455|CardNames|Two Of Diamonds"
.data:00000001000B6B80                 dq offset a44156Cardnames ; "|44156|CardNames|Three Of Diamonds"
.data:00000001000B6B88                 dq offset a51672Cardnames ; "|51672|CardNames|Four Of Diamonds"
.data:00000001000B6B90                 dq offset a45972Cardnames ; "|45972|CardNames|Five Of Diamonds"
.data:00000001000B6B98                 dq offset a47206Cardnames ; "|47206|CardNames|Six Of Diamonds"
.data:00000001000B6BA0                 dq offset a48399Cardnames ; "|48399|CardNames|Seven Of Diamonds"
.data:00000001000B6BA8                 dq offset a47847Cardnames ; "|47847|CardNames|Eight Of Diamonds"
.data:00000001000B6BB0                 dq offset a48606Cardnames ; "|48606|CardNames|Nine Of Diamonds"
.data:00000001000B6BB8                 dq offset a61278Cardnames ; "|61278|CardNames|Ten Of Diamonds"
.data:00000001000B6BC0                 dq offset a52038Cardnames ; "|52038|CardNames|Jack Of Diamonds"
.data:00000001000B6BC8                 dq offset a54643Cardnames ; "|54643|CardNames|Queen Of Diamonds"
.data:00000001000B6BD0                 dq offset a48902Cardnames ; "|48902|CardNames|King Of Diamonds"
.data:00000001000B6BD8                 dq offset a46672Cardnames ; "|46672|CardNames|Ace Of Diamonds"
.data:00000001000B6BE0                 dq offset a41049Cardnames ; "|41049|CardNames|Two Of Spades"
.data:00000001000B6BE8                 dq offset a49327Cardnames ; "|49327|CardNames|Three Of Spades"
.data:00000001000B6BF0                 dq offset a51933Cardnames ; "|51933|CardNames|Four Of Spades"
.data:00000001000B6BF8                 dq offset a42651Cardnames ; "|42651|CardNames|Five Of Spades"
.data:00000001000B6C00                 dq offset a65342Cardnames ; "|65342|CardNames|Six Of Spades"
.data:00000001000B6C08                 dq offset a53644Cardnames ; "|53644|CardNames|Seven Of Spades"
.data:00000001000B6C10                 dq offset a54466Cardnames ; "|54466|CardNames|Eight Of Spades"
.data:00000001000B6C18                 dq offset a56874Cardnames ; "|56874|CardNames|Nine Of Spades"
.data:00000001000B6C20                 dq offset a46756Cardnames ; "|46756|CardNames|Ten Of Spades"
.data:00000001000B6C28                 dq offset a62876Cardnames ; "|62876|CardNames|Jack Of Spades"
.data:00000001000B6C30                 dq offset a64633Cardnames ; "|64633|CardNames|Queen Of Spades"
.data:00000001000B6C38                 dq offset a46215Cardnames ; "|46215|CardNames|King Of Spades"
.data:00000001000B6C40                 dq offset a60450Cardnames ; "|60450|CardNames|Ace Of Spades"
.data:00000001000B6C48                 dq offset a51010Cardnames ; "|51010|CardNames|Two Of Hearts"
.data:00000001000B6C50                 dq offset a64948Cardnames ; "|64948|CardNames|Three Of Hearts"
.data:00000001000B6C58                 dq offset a43079Cardnames ; "|43079|CardNames|Four Of Hearts"
.data:00000001000B6C60                 dq offset a57131Cardnames ; "|57131|CardNames|Five Of Hearts"
.data:00000001000B6C68                 dq offset a58953Cardnames ; "|58953|CardNames|Six Of Hearts"
.data:00000001000B6C70                 dq offset a45105Cardnames ; "|45105|CardNames|Seven Of Hearts"
.data:00000001000B6C78                 dq offset a47775Cardnames ; "|47775|CardNames|Eight Of Hearts"
.data:00000001000B6C80                 dq offset a41825Cardnames ; "|41825|CardNames|Nine Of Hearts"
.data:00000001000B6C88                 dq offset a41501Cardnames ; "|41501|CardNames|Ten Of Hearts"
.data:00000001000B6C90                 dq offset a47108Cardnames ; "|47108|CardNames|Jack Of Hearts"
.data:00000001000B6C98                 dq offset a55659Cardnames ; "|55659|CardNames|Queen Of Hearts"
.data:00000001000B6CA0                 dq offset a44572Cardnames ; "|44572|CardNames|King Of Hearts"
.data:00000001000B6CA8                 dq offset a44183Cardnames ; "|44183|CardNames|Ace Of Hearts"

If you want to do this to someone, be sure his/her mental health is stable.

Aside of function names from PDB file, there are lots of Log() function calls that can help significantly, because the Solitaire game reports about what it's doing right now.

Homework: try to "remove" several cards or two of clubs. And what if to swap card names in arrays of strings?

I also tried to pass a numbers like 0, 0..50 to Card:Init() (so to have 2 zeroes in a list of 52 numbers). Then I saw two "two of clubs" cards at one moment, but Solitaire behaves erratically.

This is patched Windows 7 Solitare: https://yurichev.com/blog/solitaire/Solitaire51.exe.

Part II.

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