I want to warn you about security vulnerabilities in ADSL modem Callisto 821+ (SI2000 Callisto821+ Router).
These are Cross-Site Request Forgery and Cross-Site Scripting vulnerabilities. Which I've found in your modem. In April I've already drew attention of Ukrtelecom's representative (and this modem was bough at Ukrtelecom) about multiple vulnerabilities in this model of Callisto modems (and other models also could be affected).
These attacks should be conducted on modem owner, which is logged into control panel. Taking into account that it's unlikely to catch him in this state, then it's possible to use before-mentioned vulnerabilities (http://websecurity.com.ua/5161/) for conducting of remote login (for logining him into control panel). After that it's possible to conduct CSRF or XSS attack.
This vulnerability allows to save modem's configuration (it's needed at changing of configuration).
This vulnerability allows to delete user from the list of accounts in admin panel. For attack it's needed to know user's login.
In this form there is also a persistent XSS vulnerability.
In this case the code will be executed immediately, and also at visiting of pages http://192.168.1.1/system/events.html and http://192.168.1.1/shared/event_log_selection.html.
Vulnerable is the next model: SI2000 Callisto821+ Router: X7821 Annex A v18.104.22.168 / Argon 4x1 CSP v1.0 (ISOS 9.0) [4.3.4-5.1]. This model with other firmware and also other models of Callisto also must be vulnerable.
I mentioned about these vulnerabilities at my site (http://websecurity.com.ua/5175/).
Best wishes & regards, MustLive Administrator of Websecurity web site http://websecurity.com.ua