Cisco Security Advisory
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AV:N/AC:M/Au:N/C:N/I:P/A:N/E:F/RL:OF/RC:C
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A vulnerability in the Transport Layer Security (TLS) code on the Cisco Adaptive Security Appliance (ASA) could allow an unauthenticated, remote attacker to modify the contents of an encrypted TLS packet without detection of the modifications.
The vulnerability is due to an error on the firmware of the Cavium Networks cryptographic module. Due to this vulnerability, the message authentication code (MAC) on a TLS packet is not being checked. An attacker could exploit this vulnerability by intercepting encrypted packets in transit and modifying their contents. Such packets would be decrypted by the ASA, but the modification would not be detected.
Cisco has confirmed the vulnerability and released software updates.
To exploit this vulnerability, the attacker may need to be in a position to perform a man-in-the-middle attack and be able to intercept encrypted TLS packets in transit from a targeted device, making exploitation more difficult in environments that restrict network access from untrusted sources.
A successful exploit of this vulnerability does not allow an attacker to decrypt the packets in transit or obtain information about the session keys being used for the TLS connection.
Cisco would like to that Mr. Yngve Pettersen from TLS Prober Labs for reporting this vulnerability.
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Cisco has released bug ID CSCuu52976 for registered users, which contains additional details and an up-to-date list of affected product versions.
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Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators are advised to monitor affected systems.
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Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via email at tac@cisco.com.
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The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show LessVersion Description Section Status Date 1.0 Cisco Adaptive Security Appliance contains a vulnerability that could allow an unauthenticated, remote attacker to bypass security restrictions. Updates are available. NA Final 2015-Jul-14
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