{"id":3344,"date":"2025-04-14T19:52:30","date_gmt":"2025-04-14T10:52:30","guid":{"rendered":"https:\/\/h4ck.kr\/?p=3344"},"modified":"2025-04-14T19:52:31","modified_gmt":"2025-04-14T10:52:31","slug":"lactf2024-aplet321","status":"publish","type":"post","link":"https:\/\/h4ck.kr\/?p=3344","title":{"rendered":"[LACTF2024] aplet321"},"content":{"rendered":"\n<h3 class=\"wp-block-heading\">Decompiled src \/ Analysis<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>fgets<\/code>\ub97c \ud1b5\ud574 <code>s<\/code> \ubcc0\uc218\uc5d0 \ucd5c\ub300 512\ubc14\uc774\ud2b8 \uc785\ub825\ubc1b\uc74c.<\/li>\n\n\n\n<li><code>strncmp<\/code>\ub97c \ud1b5\ud574 <code>pretty<\/code> \ubb38\uc790\uc5f4\uc758 \uac1c\uc218\uac00 <code>v6<\/code>, <code>please<\/code> \ubb38\uc790\uc5f4\uc758 \uac1c\uc218\uac00 <code>v5<\/code>\uc5d0 \uc800\uc7a5\ub428<\/li>\n\n\n\n<li>\uc870\uac74 \ucda9\uc871 \ud544\uc694: <code>v6 + v5 == 0x36 &amp;&amp; v6 - v5 == -0x18u<\/code><\/li>\n\n\n\n<li><strong><code>v6 = 15, v5 = 39<\/code>, \uc989 flag \ubb38\uc790\uc5f4\uacfc \ud568\uaed8 pretty 15\ubc88\uacfc please 39\ubc88 \ub4e4\uc5b4\uac00\uc57c\ud568<\/strong><\/li>\n<\/ul>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"c\" data-enlighter-theme=\"dracula\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">int __fastcall main(int argc, const char **argv, const char **envp)\n{\n  char *v3; \/\/ rbx\n  size_t v4; \/\/ rax\n  int v5; \/\/ ebp\n  int v6; \/\/ r12d\n  char *v7; \/\/ r15\n  char s[568]; \/\/ [rsp+10h] [rbp-238h] BYREF\n\n  v3 = s;\n  setbuf(stdout, 0);\n  puts(\"hi, i'm aplet321. how can i help?\");\n  fgets(s, 512, stdin);\n  v4 = strlen(s);\n  if ( v4 &lt;= 5 )\n    goto LABEL_10;\n  v5 = 0;\n  v6 = 0;\n  v7 = &amp;s[(unsigned int)(v4 - 6) + 1];\n  do\n  {\n    v6 += strncmp(v3, \"pretty\", 6u) == 0;\n    v5 += strncmp(v3++, \"please\", 6u) == 0;\n  }\n  while ( v3 != v7 );\n  if ( v5 )\n  {\n    if ( strstr(s, \"flag\") )\n    {\n      if ( v6 + v5 == 0x36 &amp;&amp; v6 - v5 == -0x18u )\n      {\n        puts(\"ok here's your flag\");\n        system(\"cat flag.txt\");\n      }\n      else\n      {\n        puts(\"sorry, i'm not allowed to do that\");\n      }\n    }\n    else\n    {\n      puts(\"sorry, i didn't understand what you mean\");\n    }\n  }\n  else\n  {\nLABEL_10:\n    puts(\"so rude\");\n  }\n  return 0;\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">solve.py<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"python\" data-enlighter-theme=\"dracula\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">from pwn import *\n# context.log_level = 'debug'\ncontext(arch='amd64', os='linux')\nwarnings.filterwarnings('ignore')\n\np = process(\".\/aplet321\")\n\nsla = p.sendlineafter\nsa = p.sendafter\n\npayload = b\"flag\"\npayload += b\"pretty\"*15\npayload += b\"please\"*39\nsla(b\"hi, i'm aplet321. how can i help?\\n\", payload)\n\np.interactive()<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">Result<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"raw\" data-enlighter-theme=\"dracula\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">seo@seo:~\/study\/LACTF2024\/aplet321$ python3 solve.py\n[+] Starting local process '.\/aplet321': pid 14118\n[*] Switching to interactive mode\nok here's your flag\ncat: flag.txt: No such file or directory\n[*] Got EOF while reading in interactive\n$\n[*] Interrupted\n[*] Process '.\/aplet321' stopped with exit code 0 (pid 14118)<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Decompiled src \/ Analysis solve.py Result<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","footnotes":""},"categories":[19],"tags":[24],"class_list":["post-3344","post","type-post","status-publish","format-standard","hentry","category-ctf-private","tag-reversing"],"_links":{"self":[{"href":"https:\/\/h4ck.kr\/index.php?rest_route=\/wp\/v2\/posts\/3344","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/h4ck.kr\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/h4ck.kr\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/h4ck.kr\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/h4ck.kr\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3344"}],"version-history":[{"count":1,"href":"https:\/\/h4ck.kr\/index.php?rest_route=\/wp\/v2\/posts\/3344\/revisions"}],"predecessor-version":[{"id":3345,"href":"https:\/\/h4ck.kr\/index.php?rest_route=\/wp\/v2\/posts\/3344\/revisions\/3345"}],"wp:attachment":[{"href":"https:\/\/h4ck.kr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3344"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/h4ck.kr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3344"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/h4ck.kr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3344"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}