The OpenSSH agent permits its clients to load PKCS11 providers using the commands SSH_AGENTC_ADD_SMARTCARD_KEY and SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED if OpenSSH was compiled with the ENABLE_PKCS11 flag (normally enabled) and the agent isn’t locked. For these commands, the client has to specify a provider name. Th e agent passes this provider name to a subprocess (via ssh-agent.c:process_add_smartcard_key -> ssh-pkcs11-client.c:pkcs11_add_provider -> ssh-pkcs11-client.c:s end_msg), and the subprocess receives it and passes it to dlopen() (via ssh-pkcs 11-helper.c:process -> ssh-pkcs11-helper.c:process_add -> ssh-pkcs11.c:pkcs11_ad d_provider -> dlopen). No checks are performed on the provider name, apart from testing whether that provider is already loaded. This means that, if a user connects to a malicious SSH server with agent forwarding enabled and the malicious server has the ability to place a file with attacker-controlled contents in the victim’s filesystem, the SSH server can execute code on the user’s machine.<\/p>\n","protected":false},"excerpt":{"rendered":"
The OpenSSH agent permits its clients to load PKCS11 providers using the commands SSH_AGENTC_ADD_SMARTCARD_KEY and SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED if OpenSSH was compiled with the ENABLE_PKCS11 flag (normally enabled) and the agent isn’t…<\/p>\n","protected":false},"author":439,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"","_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[43],"tags":[],"class_list":["post-27342","post","type-post","status-publish","format-standard","hentry","category-exploit"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p4bBYZ-770","_links":{"self":[{"href":"https:\/\/deepquest.code511.com\/blog\/wp-json\/wp\/v2\/posts\/27342","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/deepquest.code511.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/deepquest.code511.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/deepquest.code511.com\/blog\/wp-json\/wp\/v2\/users\/439"}],"replies":[{"embeddable":true,"href":"https:\/\/deepquest.code511.com\/blog\/wp-json\/wp\/v2\/comments?post=27342"}],"version-history":[{"count":0,"href":"https:\/\/deepquest.code511.com\/blog\/wp-json\/wp\/v2\/posts\/27342\/revisions"}],"wp:attachment":[{"href":"https:\/\/deepquest.code511.com\/blog\/wp-json\/wp\/v2\/media?parent=27342"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/deepquest.code511.com\/blog\/wp-json\/wp\/v2\/categories?post=27342"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/deepquest.code511.com\/blog\/wp-json\/wp\/v2\/tags?post=27342"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}