Cisco Small Business Voice Gateways and Analog Telephone Adapters (ATAs) and Cisco Small Business SPA 500 Series IP Phones contain a vulnerability that could allow an unauthenticated, remote attacker to conduct cross-site scripting attacks.
The vulnerability is due to a lack of sanitization of user-supplied input in the SIP INVITE request FROM field. An unauthenticated, remote attacker could exploit this vulnerability by sending a crafted SIP INVITE message with injected exploit code. If the user visits the device's web management console (Call Log), the attacker could execute arbitrary script code in the user's browser in the security context of the affected site.
Proof-of-concept code is publicly available.
Cisco has confirmed this vulnerability and released updated software.
To exploit this vulnerability, an attacker must inject a crafted SIP message into the network, which may require access to trusted, internal network resources. This access requirement reduces the exposure of this vulnerability. Additionally, the attacker must then provide a link via e-mail, instant messaging, or another form of communication that directs a user to the affected device's Call Log web page and use misleading language or instructions to persuade the user to follow the provided link.
This vulnerability was discovered by Alexander Zaitsev and Gleb Gritsai, Positive Research Center (Positive Technologies Company).