News

Cisco Discloses Serious IOS Flaw

Cisco Systems Inc. last week alerted users to multiple vulnerabilities in the Secure Shell (SSH) server implementation that ships with version 12.4 of its Internetwork Operating System (IOS).

In some cases, Cisco warned, a malicious attacker could exploit a flaw in the IOS SSH implementation to trigger denial of service (DoS) and reload the device.

Elsewhere, Cisco confirmed, attackers can exploit its IOS SSH implementation to generate spurious memory access errors. If an attacker is able to repeatedly reboot an IOS device, extended DoS could result, Cisco warned.

Cisco lists the IOS SSH daemon (SSHd) as an "optional" service, but its use is nonetheless highly recommended, because SSH facilitates secure command-line connectivity to IOS devices. Not all IOS devices are affected. According to Cisco, certain devices powered by IOS version 12.4 (and running SSH) may be affected. Versions of IOS prior to IOS 12.4 (including all 10.x and 11.x releases), as well as Cisco IOS XR are not affected, according to Cisco.

Cisco has published a software update and recommends any of workarounds for customers that don't wish to update their software. The first and most obvious workaround, according to Cisco representatives, is to disable the IOS SSHd. Users can also configure VTY access classes to allow only trusted hosts to establish SSH connections. Elsewhere, Cisco said, users can configure infrastructure Access Control Lists (iACL), a recommended security best practice, to restrict network traffic from targeting infrastructure devices.

In addition, Cisco said, customers can tap TELNET as an insecure alternative to SSH.

According to Cisco, the SSHd flaws were discovered internally or as a result of customer service requests. As a result, Cisco said it does not know of any malicious activity associated with the SSHd flaws.

About the Author

Stephen Swoyer is a Nashville, TN-based freelance journalist who writes about technology.

Featured

  • Microsoft Expands Azure AD Password Lengths, Adds Conditional Access Controls

    Microsoft announced a couple of Azure Active Directory enhancements this week regarding password lengths and new conditional access controls for IT pros.

  • Attack Surface Analyzer 2.0 Available for Checking Software Installs

    Microsoft this week described Attack Surface Analyzer 2.0, an updated tool for checking software installations that's now built using open source code.

  • What Causes Hyper-V Replication Failures?

    Hyper-V replication failures happen rarely, but their impact can be catastrophic when they do. Know the scenarios that are likely to trigger a replication failure.

  • Microsoft Touts Using HyperClear To Address Intel Processor Woes

    Microsoft is again promoting its HyperClear Hyper-V hypervisor technology as a potential balm for organizations trying to come to grips with Intel's latest speculative execution side-channel attack disclosures.

comments powered by Disqus

Office 365 Watch

Sign up for our newsletter.

Terms and Privacy Policy consent

I agree to this site's Privacy Policy.