Cisco’s warning: Critical flaw in IOS routers allows ‘complete system compromise’

BY admin June 6, 2020 Privacy & Security 2 views

Cisco has disclosed four critical security flaws affecting router equipment that uses its IOS XE and IOS software. 

Cisco has disclosed four critical security flaws affecting router equipment that uses its IOS XE and IOS software. 

The four critical flaws are part of Cisco’s June 3 semi-annual advisory bundle for IOS XE and IOS networking software, which includes 23 advisories describing 25 vulnerabilities. 

The 9.8 out of 10 severity bug, CVE-2020-3227, concerns the authorization controls for the Cisco IOx application hosting infrastructure in Cisco IOS XE Software, which allows a remote attacker without credentials to execute Cisco IOx API commands without proper authorization.

IOx mishandles requests for authorization tokens, allowing an attacker to exploit the flaw with a specially crafted API call to request the token and then execute Cisco IOx API commands on the device, according Cisco

Cisco has also published two more advisories covering three critical IOS flaws affecting its industrial routers. 

CVE-2020-3205 is a command-injection vulnerability in Cisco’s implementation of the inter-VM channel of Cisco IOS Software for Cisco 809 and 829 Industrial Integrated Services Routers (Industrial ISRs) and Cisco 1000 Series Connected Grid Routers (CGR1000). 

The software doesn’t adequately validate signaling packets directed to the Virtual Device Server (VDS), which could allow an attacker to send malicious packets to an affected device, gain control of VDS and then completely compromise the system, including the IOS VM and guest VM. 

VDS handles access to devices that are shared by IOS and the guest OS, such as flash memory, USB ports, and the console. 

“A successful exploit could allow the attacker to execute arbitrary commands in the context of the Linux shell of VDS with the privileges of the root user,” Cisco said

“Because the device is designed on a hypervisor architecture, exploitation of a vulnerability that affects the inter-VM channel may lead to a complete system compromise.”

CVE-2020-3198 and CVE-2020-3258 are part of the same advisory and concern a remote code execution vulnerability in the same industrial Cisco routers. 

Cisco describes its 800 Series of industrial routers as highly secure compact devices designed for harsh environments, with applications ranging from overseeing IoT gateway tasks in distribution automation, pipeline and road monitoring, fleet management and mass transport.

The flaw CVE-2020-3198 allows an unauthenticated, remote attacker to execute arbitrary code on affected systems or cause it to crash and reload. 

An attacker could exploit the vulnerability by sending malicious UDP packets over IPv4 or IPv6 to an affected device. Cisco notes that the bug can be mitigated by implementing an access control list that restricts inbound traffic to UDP port 9700 of the device. It has a severity score of 9.8 out of 10. 

“The vulnerability is due to incorrect bounds checking of certain values in packets that are destined for UDP port 9700 of an affected device,” Cisco said

“An attacker could exploit this vulnerability by sending malicious packets to an affected device. When the packets are processed, an exploitable buffer overflow condition may occur. A successful exploit could allow the attacker to remotely execute code in the context of the Cisco IOS Software VM that is running on an affected system or cause an affected device to reload.”

The second bug, CVE-2020-3258, is less severe with a score of 5.7 out of 10 and could allow an unauthenticated local attacker to execute arbitrary code on the device. However, the attacker also must have valid user credentials at privilege level 15, the highest level in Cisco’s scheme. 

The vulnerability allows an attacker to modify the device’s run-time memory, overwrite system memory locations and execute arbitrary code on the affected device. 

All four bugs were found by Cisco’s penetration testing squad, the Cisco Advanced Security Initiatives Group


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