The certificate handling vulnerability, which carries a CVSS severity score of 6.8, affects all versions of the BlackBerry device software. The flaw allows malicious hackers to trick BlackBerry device users into connecting to an attacker-controlled Web site, RIM warned in an advisory.
Here's the crux of the problem:
A malicious user could create a web site that includes a certificate that is purposely altered using null (hidden) characters in the certificate's Common Name (CN) field or otherwise manipulated to deceive a BlackBerry device user into believing they have connected to a trusted web site.
If the malicious user then performs a phishing-style attack by sending the BlackBerry device user a link to the web site in an SMS or email message that appears to be from a trusted source, and the BlackBerry device user chooses to access that site, the BlackBerry Browser will correctly detect the mismatch between the certificate and the domain name and display a dialog box that prompts the user to close the connection. However, the dialog box does not display null characters, so the user may believe they are connecting to a trusted site and disregard the recommended action to close the connection.
This screenshot provided by RIM shows an example of a BlackBerry Browser dialog box that does not clearly indicate that there is a mismatch between the web server address and its associated certificate:
BlackBerry users are urged to download and apply the patch the BlackBerry Device Software as soon as possible.
In the meantime, RIM recommends that BlackBerry device users exercise caution when clicking on links that they receive in email or SMS messages.
"If a user visits a site that causes a BlackBerry Browser dialog box to warn the user about continuing the connection, the user should select Close connection," the company said.