Arch Linux Security Advisory ASA-201609-24 ========================================== Severity: High Date : 2016-09-26 CVE-ID : CVE-2016-6304 CVE-2016-2178 CVE-2016-2177 CVE-2016-2183 CVE-2016-2182 CVE-2016-6303 CVE-2016-2179 CVE-2016-2180 CVE-2016-2181 CVE-2016-6302 CVE-2016-6306 Package : lib32-openssl Type : multiple issues Remote : Yes Link : https://wiki.archlinux.org/index.php/CVE Summary ======= The package lib32-openssl before version 1:1.0.2.i-1 is vulnerable to multiple issues including denial of service, private key recovery, information disclosure and arbitrary code execution. Resolution ========== Upgrade to 1:1.0.2.i-1. # pacman -Syu "lib32-openssl>=1:1.0.2.i-1" The problems have been fixed upstream in version 1.0.2.i. Workaround ========== None. Description =========== - CVE-2016-6304 (denial of service) A malicious client can send an excessively large OCSP Status Request extension. If that client continually requests renegotiation, sending a large OCSP Status Request extension each time, then there will be unbounded memory growth on the server. This will eventually lead to a Denial Of Service attack through memory exhaustion. Servers with a default configuration are vulnerable even if they do not support OCSP. Builds using the "no-ocsp" build time option are not affected. - CVE-2016-2178 (private key recovery) Operations in the DSA signing algorithm should run in constant time in order to avoid side channel attacks. A flaw in the OpenSSL DSA implementation means that a non-constant time codepath is followed for certain operations. This has been demonstrated through a cache-timing attack to be sufficient for an attacker to recover the private DSA key. - CVE-2016-2177 (denial of service) OpenSSL through 1.0.2h incorrectly uses pointer arithmetic for heap- buffer boundary checks, which might allow remote attackers to cause a denial of service (integer overflow and application crash) or possibly have unspecified other impact by leveraging unexpected malloc behavior, related to s3_srvr.c, ssl_sess.c, and t1_lib.c. - CVE-2016-2183 (information disclosure) SWEET32 (https://sweet32.info) is an attack on older block cipher algorithms that use a block size of 64 bits. In mitigation for the SWEET32 attack DES based ciphersuites have been moved from the HIGH cipherstring group to MEDIUM. - CVE-2016-2182 (arbitrary code execution) The function BN_bn2dec() does not check the return value of BN_div_word(). This can cause an OOB write if an application uses this function with an overly large BIGNUM. This could be a problem if an overly large certificate or CRL is printed out from an untrusted source. TLS is not affected because record limits will reject an oversized certificate before it is parsed. - CVE-2016-6303 (arbitrary code execution) An overflow can occur in MDC2_Update() either if called directly or through the EVP_DigestUpdate() function using MDC2. If an attacker is able to supply very large amounts of input data after a previous call t MVP_EncryptUpdate() with a partial block then a length check can overflow resulting in a heap corruption. The amount of data needed is comparable to SIZE_MAX which is impractical on most platforms. - CVE-2016-2179 (denial of service) In a DTLS connection where handshake messages are delivered out-of- order those messages that OpenSSL is not yet ready to process will be buffered for later use. Under certain circumstances, a flaw in the logic means that those messages do not get removed from the buffer even though the handshake has been completed. An attacker could force up to approx. 15 messages to remain in the buffer when they are no longer required. These messages will be cleared when the DTLS connection is closed. The default maximum size for a message is 100k. Therefore the attacker could force an additional 1500k to be consumed per connection. By opening many simultaneous connections an attacker could cause a DoS attack through memory exhaustion. - CVE-2016-2180 (denial of service) The function TS_OBJ_print_bio() misuses OBJ_obj2txt(): the return value is the total length the OID text representation would use and not the amount of data written. This will result in OOB reads when large OIDs are presented. - CVE-2016-2181 (denial of service) A flaw in the DTLS replay attack protection mechanism means that records that arrive for future epochs update the replay protection "window" before the MAC for the record has been validated. This could be exploited by an attacker by sending a record for the next epoch (which does not have to decrypt or have a valid MAC), with a very large sequence number. This means that all subsequent legitimate packets are dropped causing a denial of service for a specific DTLS connection. - CVE-2016-6302 (denial of service) If a server uses SHA512 for TLS session ticket HMAC it is vulnerable to a DoS attack where a malformed ticket will result in an OOB read which will ultimately crash. The use of SHA512 in TLS session tickets is comparatively rare as it requires a custom server callback and ticket lookup mechanism. - CVE-2016-6306 (denial of service) In OpenSSL 1.0.2 and earlier some missing message length checks can result in OOB reads of up to 2 bytes beyond an allocated buffer. There is a theoretical DoS risk but this has not been observed in practice on common platforms. The messages affected are client certificate, client certificate request and server certificate. As a result the attack can only be performed against a client or a server which enables client authentication. Impact ====== A remote attacker is able to execute arbitrary code, recovery private keys, disclose sensitive information or perform a denial of service attack via various vectors. References ========== https://www.openssl.org/news/secadv/20160922.txt https://access.redhat.com/security/cve/CVE-2016-6304 https://access.redhat.com/security/cve/CVE-2016-2178 https://access.redhat.com/security/cve/CVE-2016-2177 https://access.redhat.com/security/cve/CVE-2016-2183 https://access.redhat.com/security/cve/CVE-2016-2182 https://access.redhat.com/security/cve/CVE-2016-6303 https://access.redhat.com/security/cve/CVE-2016-2179 https://access.redhat.com/security/cve/CVE-2016-2180 https://access.redhat.com/security/cve/CVE-2016-2181 https://access.redhat.com/security/cve/CVE-2016-6302 https://access.redhat.com/security/cve/CVE-2016-6306