Sun ONE Vulnerability Comes to Light

A vulnerability in the Sun ONE Application Server can give an attacker control over the Web server.

Security researchers have discovered a vulnerability in Sun Microsystems Inc.s Sun ONE Application Server that can give an attacker control over the Web server.

The vulnerability, found by researchers at @stake Inc., in Cambridge, Mass., is a stack buffer overflow in the Connector Module. The module, which ships with the Application Server, is a Netscape API plugin that integrates the Sun ONE Web Server with the Application Server.

The module uses a static buffer to handle the incoming request URI (Universal Resource Identifier). All an attacker needs to do to exploit this flaw is send an overly long request URI to the module. This will overwrite the saved extended instruction pointer register.

Resource Library:

The vulnerability affects versions 6.0 and 6.5 of the Application Server. Sun, based in Santa Clara, Calif., has only produced a patch for 6.5, however. That fix is included in Service Pack 1 for the server, which is downloadable at Suns Web site.

There are several workarounds for companies that have 6.0 deployed, according to @stakes advisory. The researchers recommend that users do one of three things: write an NSAPI module that checks the length of HTTP request URIs; terminate the SSL session on a device in front of the Sun ONE Web server, then install an intrusion detection sensor to inspect the clear-text traffic and write a filter to detect overly long HTTP request URIs; or terminate the SSL session on a reverse proxy that does data validation on all HTTP request headers.

The full @stake advisory, available here, provides an example of an NSAPI module that performs the correct checks.

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