Title: Netscape Servers Suite Heap Buffer Overflow Vulnerability
Severity: HIGH
Description:
An exploitable heap buffer overflow vulnerability was discovered in the Netscape Directory Server product. The Netscape Certificate Management System has also several server components that share the problem. Vulnerable systems allow the execution of arbitrary code as the user running the services.
The Netscape Directory Server 4.12 provides a Web to LDAP gateway, by means of the Directory Services Gateway (DSGW) web server. No authentication credentails are required from the client to access DSGW. The same service is installed and used as part of the Certificate Management System (Netscape/iPlanet CMS 4.2) and in this case it listens on a tcp port choosen during the installation process (24326/tcp in this example).
A request with an URI as follows:
http://server:24326/dsgw/bin/search?context=<1011 'a' chars>
will overflow a buffer located in the heap.
This buffer is allocated at 404501 with a call to an internal function that ends up calling MSVCRT!malloc. The buffer is allocated with a fixed size of 1024 bytes.
T hen at 40455B a call to sprintf is made like this:
sprintf(pFixedBuffer, "%s$$LANGDIR/%s.conf", "../context/", userbuff);
since sprintf doesn't do any bounds checking, the buffer can be overflowed depending on the size of 'userbuff' which is the argument the user specifies to the 'context=' parameter when calling the vulnerable program. A string of 999 bytes is enough to overflow the 'pFixedBuffer' by 1 byte and cause an exception.
Due to the nature of the data overwritten, this vulnerability could be exploited, being possible to execute arbitrary machine code.
The same problem seems to be present in almost all the binaries (12) in the Netscape\Server4\dsgw\bin directory (except for tutor).
Affected Products:
- Netscape Certificate Server 4.2.0
- Netscape Directory Server 4.12.0
References:
- CORE: CORE SDI Homepage
- Netscape: Netscape Security
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