Cisco inadvertently introduced a critical vulnerability in its email security appliances by forgetting to remove an internal testing interface from software releases made available to customers.
According to Cisco, the vulnerability affects both physical and virtual Email Security Appliances (ESA) running IronPort AsyncOS software. The flaw allows a remote attacker to gain complete control of the affected device with root privileges.
The security hole, tracked as CVE-2016-6406, is caused by an internal testing and debugging interface Cisco installed for the manufacturing phase. Since the interface made it into production releases, attackers can connect to it without authentication and hijack the vulnerable device.
The flaw affects various 9.1.2, 9.7.2 and 10.0.0 software releases. The good news is that a device is not vulnerable if it has been rebooted more than once, since the problematic interface is automatically disabled after the second reboot.
Cisco has released updates for versions 9.1.2 and 9.7.2, and a patch for version 10.0.0 is expected to become available in early October. However, the networking giant released an update for the Enrollment Client component that prevents the flaw from being exploited regardless of which software version is running.
As a workaround, customers can simply reboot their devices using the reboot command from the command-line interface (CLI). The internal testing and debugging interface will be disabled once the reboot has completed.
The vulnerability has been found during the resolution of a support case and there is no evidence that it has been exploited for malicious purposes.
This week, Cisco also released 10 advisories describing high severity denial-of-service (DoS) vulnerabilities in IOS and IOS XE software. The security holes were identified by Cisco and one of the company’s partners.
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