Arch Linux Security Advisory ASA-201712-11 ========================================== Severity: Medium Date : 2017-12-17 CVE-ID : CVE-2017-3735 CVE-2017-3736 CVE-2017-3737 CVE-2017-3738 Package : lib32-openssl-1.0 Type : multiple issues Remote : Yes Link : https://security.archlinux.org/AVG-480 Summary ======= The package lib32-openssl-1.0 before version 1.0.2.n-1 is vulnerable to multiple issues including information disclosure, private key recovery and denial of service. Resolution ========== Upgrade to 1.0.2.n-1. # pacman -Syu "lib32-openssl-1.0>=1.0.2.n-1" The problems have been fixed upstream in version 1.0.2.n. Workaround ========== None. Description =========== - CVE-2017-3735 (denial of service) A security issue has been found in OpenSSL < 1.1.0g. If an X.509 certificate has a malformed IPAddressFamily extension, OpenSSL could do a one-byte buffer overread. The most likely result would be an erroneous display of the certificate in text format. - CVE-2017-3736 (information disclosure) A carry propagation bug has been found in OpenSSL < 1.1.0g in the x86_64 Montgomery squaring procedure. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH are considered just feasible (although very difficult) because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be very significant and likely only accessible to a limited number of attackers. An attacker would additionally need online access to an unpatched system using the target private key in a scenario with persistent DH parameters and a private key that is shared between multiple clients. This only affects processors that support the BMI1, BMI2 and ADX extensions like Intel Broadwell (5th generation) and later or AMD Ryzen. - CVE-2017-3737 (information disclosure) OpenSSL 1.0.2 (starting from version 1.0.2b) introduced an "error state" mechanism. The intent was that if a fatal error occurred during a handshake then OpenSSL would move into the error state and would immediately fail if you attempted to continue the handshake. This works as designed for the explicit handshake functions (SSL_do_handshake(), SSL_accept() and SSL_connect()), however due to a bug it does not work correctly if SSL_read() or SSL_write() is called directly. In that scenario, if the handshake fails then a fatal error will be returned in the initial function call. If SSL_read()/SSL_write() is subsequently called by the application for the same SSL object then it will succeed and the data is passed without being decrypted/encrypted directly from the SSL/TLS record layer. In order to exploit this issue an application bug would have to be present that resulted in a call to SSL_read()/SSL_write() being issued after having already received a fatal error. - CVE-2017-3738 (private key recovery) There is an overflow bug in the AVX2 Montgomery multiplication procedure used in exponentiation with 1024-bit moduli. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH1024 are considered just feasible, because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be significant. However, for an attack on TLS to be meaningful, the server would have to share the DH1024 private key among multiple clients, which is no longer an option since CVE-2016-0701. Impact ====== A remote attacker can cause a denial of service via a crafted X.509 certificate. Furthermore a remote attacker with online access to an unpatched system on a vulnerable architecture can access sensitive information like a private key. References ========== https://www.openssl.org/news/vulnerabilities.html#2017-3735 https://www.openssl.org/news/secadv/20170828.txt https://github.com/openssl/openssl/commit/b23171744b01e473ebbfd6edad70c1c3825ffbcd https://www.openssl.org/news/vulnerabilities.html#2017-3736 https://www.openssl.org/news/secadv/20171102.txt https://github.com/openssl/openssl/commit/668a709a8d7ea374ee72ad2d43ac72ec60a80eee https://www.openssl.org/news/vulnerabilities.html#2017-3737 https://www.openssl.org/news/secadv/20171207.txt https://github.com/openssl/openssl/commit/898fb884b706aaeb283de4812340bb0bde8476dc https://www.openssl.org/news/vulnerabilities.html#2017-3738 https://github.com/openssl/openssl/commit/5630661aecbea5fe3c4740f5fea744a1f07a6253 https://security.archlinux.org/CVE-2017-3735 https://security.archlinux.org/CVE-2017-3736 https://security.archlinux.org/CVE-2017-3737 https://security.archlinux.org/CVE-2017-3738