CWE-121: Stack-based Buffer Overflow - CVE-2017-3193

D-Link DIR-850L, firmware versions 1.14B07, 2.07.B05, and possibly others, contains a stack-based buffer overflow vulnerability in the web administration interface HNAP service. An unauthenticated attacker may send a specially crafted POST request to http://<router-ip>/HNAP1/ with modified HNAP_AUTH and SOAPAction headers to overflow the buffer and execute arbitrary code as root. By default, remote administration is disabled, which limits web interface access to LAN-connected hosts. Other models and firmware versions may also be affected.

The DIR-850L is reportedly also affected by CVE-2016-6563, previously disclosed in vulnerability note VU#677427.

A remote, unauthenticated attacker can make a specially crafted POST request to gain arbitrary code execution as root.

The CERT/CC is currently unaware of a practical solution to this problem. The vendor has publicly disclosed the issue along with beta firmware releases (versions 1.14B07 h2ab BETA1 and 2.07B05 h1ke BETA1, depending on the device's hardware revision), which are available from the product information page, but it is unclear whether the beta releases should be considered a proper solution. Users who do not wish to apply a beta firmware update should consider the following workaround:

Restrict Access

As a general good security practice, only allow connections from trusted hosts and networks. Users are strongly encouraged to disable remote administration if it has been previously enabled.