Cisco TelePresence contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
A vulnerability in the code handling the ISDN Q.931 signaling
protocol of the Cisco TelePresence ISDN Gateway could allow an
unauthenticated, remote attacker to trigger a drop of the data channel (D-channel),
causing all calls to be terminated and preventing users from making new
The vulnerability is due to improper handling of a crafted
Q.931 STATUS message. An attacker could exploit this vulnerability by
injecting crafted packets in the Q.931 flow. An successful exploit could allow
the attacker to trigger a drop of the D-channel. As a result, all active calls handled by the affected
system will be terminated and it will not be possible to establish new calls until the D-channel
communication is restored. A software reload is necessary to restore normal behavior.
Cisco has confirmed the vulnerability in a security advisory and released software updates.
Cisco TelePresence ISDN Gateway Software versions prior to 2.2(1.92) are affected.
Attackers may require access to trusted internal networks to inject crafted packets in the Q.931 flow, reducing the possibility of a successful exploit.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.
An unauthenticated, remote attacker could exploit this vulnerability to cause all active calls on a targeted device to drop, resulting in a denial of service (DoS) condition. Also, new calls cannot be accepted or made until the affected device reloads, which would also result in a DoS condition.
The vulnerability is due to improper handling of crafted Q.931 STATUS messages by a device running the affected software.
An unauthenticated, remote attacker could exploit this vulnerability by injecting crafted packets in the Q.931 flow. A successful exploit could allow the attacker to trigger a drop of the D-channel which would cause all active calls handled by the affected system to terminate, resulting in a DoS condition.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
Administrators are advised to monitor affected systems.
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 firstname.lastname@example.org.
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