SECCON Beginners 2017 東京 Binary編

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ϓϩάϥϜ࣮ߦͷ࢓૊Έ $16 $FOUSBM1SPDFTTJOH6OJU • ػցޠΛಡΈɼ໋ྩ࣮ͣͭߦ͢Δ Ϩδελ • $16಺ʹ͋Δ࡞ۀ༻ྖҬ • ૣ͍ɼখ༰ྔ ϝϞϦ • σʔλΛهԱ͢Δ૷ஔ • ஗͍ɼେ༰ྔ © SECCON2017 All Rights Reserved 12 アドレス値 0x804860 0xdeadbeef 0x804864 Rev! 0x804868 0x90909090 メモリのイメージ図

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ΞηϯϒϦݴޠೖ໳ Y ൚༻Ϩδελ FBY • ܭࢉ΍ؔ਺ͷ໭Γ஋ʹར༻ FCY • ܭࢉʹར༻ FDY • ܭࢉ΍ϧʔϓॲཧͷΧ΢ϯλʹར༻ FEY • ܭࢉ ಛʹ৐ࢉ΍আࢉͰසൟ ʹར༻ © SECCON2017 All Rights Reserved 24 ಛघϨδελ FTQ • ݱࡏελοΫͷ௖্ͷΞυϨεΛࢦ͢ FCQ • ؔ਺಺ͰελοΫͷఈͷΞυϨεΛࢦ͢ FJQ • ࣍ʹ࣮ߦ͢Δ໋ྩͷΞυϨεΛࢦ͢ ※必ずしもこれらの意味を準拠するとは限らない

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ΞηϯϒϦݴޠೖ໳ Y ࠓճѻ͏໋ྩҰཡ • NPW • MFB • BEETVC • JNVMJEJW • BOEPSYPSOPU • JODEFD © SECCON2017 All Rights Reserved 25 • DNQ • KNQܥ • QVTI • QPQ • DBMM • MFBWF • SFU 3.1 代⼊命令 3.2 算術命令 3.3 条件分岐命令 3.4 スタック操作命令 3.5 関数呼び出しの命令

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ΞηϯϒϦݴޠೖ໳ Y NPW໋ྩ .07F • ஋ͷҠಈΛߦ͏໋ྩ • సૹݩͷ஋͸มԽ͠ͳ͍ సૹݩͷ஋Λసૹઌʹίϐʔ • ϝϞϦʹ֨ೲ͞Εͨ஋ʹΞΫηε͢Δʹ͸ɼ<>Λར༻ NPW FBY FCY FCYͷ஋ΛFBYʹҠಈ NPW FBY %803%153 FCYͷ஋ΛΞυϨεͱͯ͠ߟ͑ɼͦ͜ʹ֨ೲ͞Ε͍ͯΔ஋ΛFBYʹҠಈ NPW %803%153 FCY FBYͷ஋ΛΞυϨεͱͯ͠ߟ͑ɼͦ͜ʹFCYͷ஋ΛҠಈ %803%%PVCMF8PSE CZUF ୯ҐͰΞΫηε͢Δ͜ͱΛද͢ © SECCON2017 All Rights Reserved 27

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ΞηϯϒϦݴޠೖ໳ Y MFB໋ྩ -PBE &GGFDUJWF"EESFTT • సૹݩͷΞυϨεΛܭࢉͯ͠ɼసૹઌʹ֨ೲ • ΞυϨεܭࢉͷ໋ྩ͕ͩɼࢉज़ԋࢉʹར༻͞ΕΔ৔߹΋ • NPW໋ྩͱ͸ҟͳΓܭࢉͨ͠ΞυϨεʹ֨ೲ͞Εͨ஋΁ ΞΫηε͢Δ΋ͷͰ͸ͳ͍ MFBFBY FCYͷ஋ʹΛ଍ͨ͠஋ΛFBYʹ֨ೲ͢Δ ˞FCYͷ஋ࣗ਎͸มԽ͠ͳ͍ © SECCON2017 All Rights Reserved 28

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ΞηϯϒϦݴޠೖ໳ Y BOEPSYPSOPU໋ྩ • ࿦ཧੵ࿦ཧ࿨ഉଞత࿦ཧ࿨൱ఆ YPS FBY FBY FBYͱFBYͷഉଞత࿦ཧ࿨ΛFBYʹ֨ೲ͢Δ ಉ͡஋ಉ࢜ͷഉଞత࿦ཧ࿨͸ʹͳΔ ˠϨδελͷॳظԽʹར༻Մೳ © SECCON2017 All Rights Reserved 34 mov eax, 0x0 = b8 00 00 00 00 xor eax, eax = 31 c0 余談：xorによる0初期化の⽅が機械語が短い！

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ΞηϯϒϦݴޠೖ໳ Y ৚݅෼ذ • DNQ໋ྩͱKNQܥ໋ྩͷ૊Έ߹ΘͤʹΑΓ࣮ݱ • ৚݅෼ذΛ࢖͏͜ͱͰϧʔϓॲཧΛ࣮ݱՄೳ DNQ໋ྩ $P.1BSF • Φϖϥϯυಉ࢜Λൺֱ͠ɼ݁ՌʹΑͬͯϑϥάϨδελΛߋ৽͢Δ KNQܥ໋ྩ • Φϖϥϯυ͕ࢦ͢ΞυϨεʹ੍ޚΛҠ͢ • DNQ໋ྩͷ݁ՌʹΑΓ੍ޚΛҠ͔͢Ͳ͏͔Λ෼ذͰ͖Δ © SECCON2017 All Rights Reserved 38

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ΞηϯϒϦݴޠೖ໳ Y KNQܥ໋ྩ Ұྫ • KNQ+V.1 ৚݅ແ͠ • KF+VNQJG&RVBM ౳͍͠ • KOF +VNQJG/PU&RVBM ౳͘͠ͳ͍ • KMF +VNQJG-FTTPS&RVBM ҎԼ • KHF +VNQJG(SFBUFS&RVBM Ҏ্ • KM +VNQJG-FTT ະຬ • KH +VNQJG(SFBUFS ΑΓେ͖͍ • KB+VNQJG"CPWF ΑΓେ͖͍ ˞ූ߸ແ͠੔਺ͱͯ͠ߟ͑Δ • KCF +VNQJG#FMPXPG&RVBM ҎԼ ˞ූ߸ແ͠੔਺ͱͯ͠ߟ͑Δ © SECCON2017 All Rights Reserved 39

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ΞηϯϒϦݴޠೖ໳ Y ԋश ࠷ޙʹ֨ೲ͞Ε͍ͯΔFBYͷ஋ΛٻΊΑ͏ʂ © SECCON2017 All Rights Reserved 40 アドレスプログラム eax ecx 0x8048060 mov eax, 0x1 0x8048065 mov ecx, 0x0 0x804806a jmp 0x804806c 0x804806c add eax, ecx 0x804806e inc ecx 0x804806f cmp eax, 0x3 0x8048072 jl 0x804806c

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ΞηϯϒϦݴޠೖ໳ Y ղ౴ ࠷ޙʹ֨ೲ͞Ε͍ͯΔFBYͷ஋ΛٻΊΑ͏ʂ © SECCON2017 All Rights Reserved 41 アドレスプログラム eax ecx 0x8048060 mov eax, 0x1 1 0x8048065 mov ecx, 0x0 1 0 0x804806a jmp 0x804806c 1 0 0x804806c add eax, ecx 1 0 0x804806e inc ecx 1 1 0x804806f cmp eax, 0x3 1 1 0x8048072 jl 0x804806c 1 1 ①

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ΞηϯϒϦݴޠೖ໳ Y ղ౴ ࠷ޙʹ֨ೲ͞Ε͍ͯΔFBYͷ஋ΛٻΊΑ͏ʂ © SECCON2017 All Rights Reserved 42 アドレスプログラム eax ecx 0x8048060 mov eax, 0x1 1 0x8048065 mov ecx, 0x0 1 0 0x804806a jmp 0x804806c 1 0 0x804806c add eax, ecx 2 1 0x804806e inc ecx 2 2 0x804806f cmp eax, 0x3 2 2 0x8048072 jl 0x804806c 2 2 ②

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ΞηϯϒϦݴޠೖ໳ Y ղ౴ ࠷ޙʹ֨ೲ͞Ε͍ͯΔFBYͷ஋ΛٻΊΑ͏ʂ © SECCON2017 All Rights Reserved 43 アドレスプログラム eax ecx 0x8048060 mov eax, 0x1 1 0x8048065 mov ecx, 0x0 1 0 0x804806a jmp 0x804806c 1 0 0x804806c add eax, ecx 4 2 0x804806e inc ecx 4 3 0x804806f cmp eax, 0x3 4 3 0x8048072 jl 0x804806c 4 3

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ΞηϯϒϦݴޠೖ໳ Y ؔ਺ • ϓϩάϥϜ͸௨ৗɼػೳຖʹؔ਺ʹ෼ׂ͞Ε͍ͯΔ DBMM໋ྩ $"-- • ؔ਺ͷݺͼग़࣌͠ʹར༻ • ࣮ߦ࣌ʹDBMM໋ྩͷ࣍ͷ໋ྩ͕֨ೲ͞Ε͍ͯΔΞυϨεΛελοΫʹQVTI • ؔ਺͔ΒݟΔͱ͜ͷΞυϨε͸໭ΓઌͳͷͰϦλʔϯΞυϨεͱݺ͹ΕΔ • ؔ਺ͷҾ਺͸༧ΊελοΫʹੵΜͰ͓͘ SFU໋ྩ 3&5VSO • ؔ਺͔Βݩͷؔ਺ʹ໭Δࡍʹར༻ • DBMM໋ྩͰελοΫʹอଘ͓͍ͯͨ͠ϦλʔϯΞυϨεʹ੍ޚΛ໭͢ © SECCON2017 All Rights Reserved 51

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ΞηϯϒϦݴޠೖ໳ Y ྫ ༩͑ΒΕͨ̎ͭͷ஋B CΛ଍ͨ͠஋Λฦؔ͢਺BEE © SECCON2017 All Rights Reserved 52 main: sub esp, 0x8 mov DWORD PTR [esp], 1 mov DWORD PTR [esp+0x4], 2 call add mov ebx, eax (以降省略) add: push ebp mov ebp, esp sub esp, 16 mov edx, DWORD PTR [ebp+0x8] mov eax, DWORD PTR [ebp+0xc] add eax, edx mov DWORD PTR [ebp-0x4], eax leave ret ※ スライドの都合上DWORD PTRを以後省略

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ΞηϯϒϦݴޠೖ໳ Y © SECCON2017 All Rights Reserved 57 1 4byte esp リターンアドレス 4byte esp+0xc DBMM໋ྩ͸ɼݺͼग़͠ޙͷ໋ྩͷΞυϨεΛελοΫʹQVTIͯ͠BEEʹKNQ sub esp, 0x8 mov [esp], 1 mov [esp+0x4], 2 call add mov ebx, eax esp+0x8 esp+0x4 2 4byte ebp

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ΞηϯϒϦݴޠೖ໳ Y © SECCON2017 All Rights Reserved 58 1 4byte esp esp+4 esp+8 リターンアドレス 4byte esp+12 ݺͼग़͠ݩͷؔ਺ͷFCQΛελοΫʹQVTIͯ͠อଘ add: push ebp mov ebp, esp sub esp, 16 mov edx, [ebp+8] mov eax, [ebp+12] add eax, edx mov [ebp-4], eax leave ret main関数のebp 4byte esp+16 2 4byte ebp

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ΞηϯϒϦݴޠೖ໳ Y © SECCON2017 All Rights Reserved 59 1 4byte esp esp+4 esp+8 リターンアドレス 4byte esp+12 ݺͼग़͠ݩͷؔ਺ͷFCQΛελοΫʹQVTIͯ͠อଘ main関数のebp 4byte esp+16 ebp add: push ebp mov ebp, esp sub esp, 16 mov edx, [ebp+8] mov eax, [ebp+12] add eax, edx mov [ebp-4], eax leave ret 2 4byte

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add: push ebp mov ebp, esp sub esp, 16 mov edx, [ebp+8] mov eax, [ebp+12] add eax, edx mov [ebp-4], eax leave ret ΞηϯϒϦݴޠೖ໳ Y © SECCON2017 All Rights Reserved 60 esp 1 4byte 2 4byte リターンアドレス 4byte 呼び出し元の関数のebp 4byte ebp 16byte ebp+4 ebp+8 ebp+12 BEEؔ਺಺Ͱར༻͢Δ ྖҬ ྖҬ֬อͷͨΊFTQΛখ͘͢͞Δ

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ΞηϯϒϦݴޠೖ໳ Y © SECCON2017 All Rights Reserved 61 esp 1 4byte 2 4byte リターンアドレス 4byte main関数のebp 4byte ebp 16byte ebp+4 ebp+8 ebp+12 省略 3 4byte ebp-4 add: push ebp mov ebp, esp sub esp, 16 mov edx, [ebp+8] mov eax, [ebp+12] add eax, edx ; eax = 1 + 2 mov [ebp-4], eax leave ret

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ΞηϯϒϦݴޠೖ໳ Y ࠓճѻ໋ͬͨྩҰཡ • NPW • MFB • BEETVC • JNVMJEJW • BOEPSYPSOPU • JODEFD © SECCON2017 All Rights Reserved 66 • DNQ • KNQܥ • QVTI • QPQ • DBMM • MFBWF • SFU 3.1 代⼊命令 3.2 算術命令 3.3 条件分岐命令 3.4 スタック操作命令 3.5 関数呼び出しの命令 → 付録F 参考書籍/pdf等

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͓ΘΓʹ ͜Ε͔Β্ͷεςοϓʹਐΉͨΊʹ͸ ݸਓతͳҙݟ • $$ݴޠʹ׳ΕΔ ˠ ෇࿥( • HEC ͳ Ͳ σ ό ο Ψ ΍ τ Ϩ ʔ α ʔ Λ ༻ ͍ ͨ ಈ త ղ ੳ Λ ֶ Ϳ ඞ ਢ ˠ ෇࿥$ % • 3FWFSTJOH͸҉߸΍਺ֶɼΞϧΰϦζϜͷཁૉ͕໰୊ʹ ࠞͬͯ͘͟Δ͜ͱ͕ଟ͍ͷͰɼ෯޿͍஌ࣝΛ෇͚Δ • ෆඞཁͳॲཧ͸ಡΈඈ͹͢׳Ε © SECCON2017 All Rights Reserved 69

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෇࿥$HEC HECQFEB ͷ࢖͍ํ HEC • (/6੡ͷσόοΨ • QFEB͸1ZUIPOʹΑΔHECͷ֦ு ਪ঑ σόοΨ • ର࿩తʹϓϩάϥϜΛղੳ͢Δπʔϧ ϒϨʔΫϙΠϯτ • σόοΨ͕ೝࣝͯ͠ϓϩάϥϜΛࢭΊͯ͘ΕΔ໨ҹ σόοΨΛ࢖͏ϝϦοτ • Ϩδελ΍ม਺ͷ஋ΛݟΕΔ • ϒϨʔΫϙΠϯτΛுͬͯɼͱ͋Δ໋ྩ·Ͱࣗಈ࣮ߦ © SECCON2017 All Rights Reserved 75

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෇࿥$HEC HECQFEB ͷ࢖͍ํ • ىಈ HEC ର৅ϑΝΠϧ໊ • NBJOؔ਺ʹϒϨʔΫϙΠϯτΛுΔ HECQFEBCSFBLNBJO • ΞυϨεʹϒϨʔΫϙΠϯτΛுΔ ྫYʹϒϨʔΫϙΠϯτுΔ HECQFEBCSFBLY • ໋̍ྩ࣮ͣͭߦ ؔ਺ͷதʹೖΒͳ͍ HECQFEBOFYU • ໋ྩ࣮ͣͭߦ ؔ਺ͷதʹೖΔ HECQFEBTUFQ • ϒϨʔΫϙΠϯτ·ͰࣗಈͰଓ͚Δ HECQFEBDPOUJOVF © SECCON2017 All Rights Reserved 77 • ࣮ߦ HECQFEBSVO • NBJOؔ਺Ͱࣗಈతʹࢭ·Δ࣮ߦ HECQFEBTUBSU

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෇࿥$HEC HECQFEB ͷ࢖͍ํ • ϝϞϦʹ֨ೲ͞Ε͍ͯΔ஋Λදࣔ ྫCZUF෼Λਐ਺Ͱදࣔ HECQFEBYXY ΞυϨε • ϝϞϦʹ֨ೲ͞Ε͍ͯΔจࣈྻΛදࣔ HECQFEBYTΞυϨε • Ϩδελͷத਎Λม͑Δ ྫFBYΛʹॻ͖׵͑ HECQFEBTFUFBY • ϝϞϦͷத਎Λม͑Δ ྫYGGGGEΛʹॻ͖׵͑ HECQFEBTFU\JOU^YGGGGE • ελοΫΛݟΔ ྫߦ෼දࣔ HECQFEBUFMFTDPQF © SECCON2017 All Rights Reserved 78

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෇࿥'ࢀߟॻ੶QEG౳ • ηΩϡϦςΟίϯςετνϟϨϯδϒοΫ • ηΩϡϦςΟίϯςετͷͨΊͷ$5'໰୊ू • σόοΨʹΑΔYϓϩάϥϜղੳೖ໳ʲYରԠ൛ʳ • ͨͷ͍͠όΠφϦͷา͖ํ • ϦόʔεΤϯδχΞϦϯάόΠϒϧ • ࣗ࡞ΤϛϡϨʔλͰֶͿYΞʔΩςΫνϟ • #*/"3:)"$,4 • େ೤݂Ξηϯϒϥೖ໳ • *"ΠϯςϧΞʔΩςΫνϟιϑτ΢ΣΞσϕϩούʔζɾϚχϡΞϧ © SECCON2017 All Rights Reserved 82

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෇࿥($ݴޠͷසग़ؔ਺ QSJOUGؔ਺ • ୈҰҾ਺ʹ༩͑ΒΕͨΞυϨεʹ֨ೲ͞ΕͨจࣈΛग़ྗ͢Δ TDBOGؔ਺ • จࣈΛೖྗ͢ΔɽୈೋҾ਺ʹ஋͕֨ೲ͞ΕΔɽ TUSMFOؔ਺ • ୈҰҾ਺ʹ༩͑ΒΕͨΞυϨεʹ֨ೲ͞Εͨจࣈྻͷ௕͞Λฦ͢ BUPJؔ਺ • ୈҰҾ਺ʹ༩͑ΒΕͨΞυϨεʹ֨ೲ͞ΕͨจࣈྻΛ ਺஋ʹม׵͢Δ © SECCON2017 All Rights Reserved 83

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