Issue summary: When CMS password-based decryption (RFC 3211 \/ PWRI key unwrap)
\nprocesses attacker-supplied CMS data, an attacker-chosen stream-mode KEK
\ncipher can trigger a heap out-of-bounds read in kek_unwrap_key().<\/p>\n
Impact summary: A heap buffer over-read may trigger a crash which leads to
\nDenial of Service for an application if the input buffer ends at a memory
\npage boundary and the following page is unmapped. There is no information
\ndisclosure as the over-read bytes are not revealed to the attacker.<\/p>\n
The key unwrapping function performs a check-byte test as specified in the
\nRFC that reads 7 bytes from a heap allocation that is based on the wrapped
\nkey length from the message. There is a minimum length check based on the
\nblock length of the wrapping cipher. However the cipher is selected from
\nan OID carried in the attacker’s PWRI keyEncryptionAlgorithm with no
\nrequirement that the cipher be a block cipher. When an attacker selects
\na stream-mode cipher the guard will be ineffective and the allocated buffer
\ncontaining the unwrapped key can be too small to fit the check-bytes
\nspecified in the RFC and a buffer over-read can happen.<\/p>\n
Applications calling CMS_decrypt() or CMS_decrypt_set1_password()
\n(equivalently openssl cms -decrypt -pwri_password …) on untrusted CMS
\ndata are vulnerable to this issue. No password knowledge is required: the
\nover-read happens during the unwrap attempt before any authentication
\nsucceeds.<\/p>\n
The over-read is limited to a few bytes and is not written to output, so
\nthere is no information disclosure. Triggering a crash requires the
\nallocation to border unmapped memory, which is unlikely with the normal
\nallocator.<\/p>\n
The FIPS modules are not affected by this issue.<\/p>\n","protected":false},"excerpt":{"rendered":"
Issue summary: When CMS password-based decryption (RFC 3211 \/ PWRI key unwrap)
\nprocesses attacker-supplied CMS data, an attacker-chosen stream-mode KEK
\ncipher can trigger a heap out-of-bounds read in <\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-16315","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/16315","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=16315"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=16315"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=16315"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}