Cisco IOS/IOS XE TACACS+ Client Subsystem Crafted Packet input validation

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Cisco IOS and IOS XE. This impacts an unknown function of the component TACACS+ Client Subsystem. Performing a manipulation as part of Crafted Packet results in input validation. This vulnerability is identified as CVE-2018-15369. The attack can be initiated remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Cisco IOS and IOS XE (Router Operating System) (affected version unknown). It has been classified as problematic. This affects an unknown functionality of the component TACACS+ Client Subsystem. The manipulation as part of a Crafted Packet leads to a input validation vulnerability. CWE is classifying the issue as CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. This is going to have an impact on availability. The summary by CVE is:

A vulnerability in the TACACS+ client subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to improper handling of crafted TACACS+ response packets by the affected software. An attacker could exploit this vulnerability by injecting a crafted TACACS+ packet into an existing TACACS+ session between an affected device and a TACACS+ server or by impersonating a known, valid TACACS+ server and sending a crafted TACACS+ packet to an affected device when establishing a connection to the device. To exploit this vulnerability by using either method, the attacker must know the shared TACACS+ secret and the crafted packet must be sent in response to a TACACS+ request from a TACACS+ client. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

The bug was discovered 09/26/2018. The weakness was released 10/05/2018 as cisco-sa-20180926-tacplus as confirmed advisory (Website). The advisory is shared at tools.cisco.com. This vulnerability is uniquely identified as CVE-2018-15369 since 08/17/2018. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Neither technical details nor an exploit are publicly available.

The vulnerability was handled as a non-public zero-day exploit for at least 9 days. During that time the estimated underground price was around $5k-$25k. The commercial vulnerability scanner Qualys is able to test this issue with plugin 316349 (Cisco IOS and IOS XE Software TACACS+ Client Denial of Service Vulnerability(cisco-sa-20180926-tacplus)).

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at SecurityFocus (BID 105426†). Entry connected to this vulnerability is available at VDB-124885. Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Router Operating System

Vendor

• Cisco

Name

• IOS
• IOS XE

License

• commercial

Website

• Vendor: https://www.cisco.com/

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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