The developers of OpenSSH announced on 11.08.15, the availability of version 7.0. The latest release includes new features, security and bug fixes, and cryptography improvements. According to developers, OpenSSH 7.0 primarily focuses on deprecating weak, legacy and unsafe cryptography. In future releases, OpenSSH plans on disabling MD5-based HMAC algorithms, banning the use of RSA keys smaller than 1024 bits, and disabling several ciphers. OpenSSH 7.0 addresses a total of four vulnerabilities. One of these flaws is an issue related to the keyboard-interactive authentication mechanism and it exposes servers to brute-force attacks (CVE-2015-5600). The security hole, disclosed in July allows a remote attacker to try out as many as 10,000 different passwords. The attacker would only be limited by a “login grace time” setting that is set by default to two minutes. Two other vulnerabilities, affecting only the portable version of OpenSSH, were reported. One of the security holes, a privilege separation flaw related to PAM support, allows an attacker to impersonate other users. However, the attack only works if the attacker has valid credentials and can compromise the pre-authentication process for remote code execution.
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