Using SNMP to Stage XSS Attacks

Via DarkReading -

It’s yet another new spin on a pervasive attack -- this time using the old standby Simple Network Management Protocol (SNMP) to stage cross-site scripting (XSS) attacks.

XSS, which basically forces a Website to echo malicious code that then gets loaded into a user's browser, is one of the most common vulnerabilities in Web applications. Researchers with ProCheckUp Ltd. recently discovered what they think may be a new type of attack vector, using SNMP to create a “persistent XSS” attack. Persistent XSS is a more powerful XSS attack where malicious code is stored on a Website for a period of time, and all the user has to do is view the page to get infected.

With SNMP, the attacker changes parameters in the device to then launch a persistent XSS attack. ProCheckUp found the SNMP-XSS vulnerability, as well as several others, while researching ZyXEL’s Prestige gateway products, which are commonly used in home, SOHO, and ISP networks.

“A persistent XSS attack is launched when the parameters containing the payload are printed on the browser via the web interface of the device,” writes Adrian Pastor, a security consultant with ProCheckUp, in a report. The problem lies in part with the fact that ZyXEL’s Prestige products run with SNMP, HTTP, and telnet in default mode on its WAN interface, Pastor says. “This is at least true among the ISPs used by some of our customers who we offer penetration testing services for,” he writes.

XSS expert RSnake -- aka Robert Hansen, CEO of SecTheory -- says using SNMP to launch an XSS attack is definitely an interesting approach. “It's hard to say that it's new since lots of exploits use logging variables to instantiate the XSS attack, but that's definitely the first time I've heard SNMP [being] used."

RSnake says SNMP and Web application hackers don’t typically intersect, so the attack method is an interesting mix: "Lots of hackers use SNMPwalk, but not many Web app hackers."