Tenda AC7/AC9/AC10/AC15/AC18 Web Server deviceMac memory corruption

Summaryinfo

A vulnerability was found in Tenda AC7, AC9, AC10, AC15 and AC18. It has been classified as critical. This impacts an unknown function of the component Web Server. The manipulation of the argument deviceMac as part of POST Request leads to memory corruption. This vulnerability is uniquely identified as CVE-2018-18731. Local access is required to approach this attack. No exploit exists.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Tenda AC7, AC9, AC10, AC15 and AC18. This issue affects an unknown code block of the component Web Server. The manipulation of the argument deviceMac as part of a POST Request leads to a memory corruption vulnerability. Using CWE to declare the problem leads to CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

An issue was discovered on Tenda AC7 V15.03.06.44_CN, AC9 V15.03.05.19(6318)_CN, AC10 V15.03.06.23_CN, AC15 V15.03.05.19_CN, and AC18 V15.03.05.19(6318)_CN devices. There is a buffer overflow vulnerability in the router's web server -- httpd. While processing the 'deviceMac' parameter for a post request, the value is directly used in a sprintf to a local variable placed on the stack, which overrides the return address of the function.

The bug was discovered 10/25/2018. The weakness was disclosed 10/28/2018 (Website). It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2018-18731 since 10/27/2018. The exploitation is known to be easy. Attacking locally is a requirement. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability was handled as a non-public zero-day exploit for at least 4 days. During that time the estimated underground price was around $0-$5k.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The entries VDB-126045, VDB-126048 and VDB-126046 are pretty similar. Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• Router Operating System

Vendor

• Tenda

Name

• AC7
• AC9
• AC10
• AC15
• AC18

License

• commercial

Website

• Vendor: https://www.tenda.com.cn/

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