[ISN] ISS: Critical Netscape hole could be widespread

InfoSec News isn at c4i.org
Wed Aug 25 06:20:03 EDT 2004


By Paul Roberts
IDG News Service

Security company Internet Security Systems Inc. (ISS) is warning its
customers about a critical security hole in a commonly used technology
from the Mozilla Foundation called the Netscape Network Security
Services (NSS) library that could make Web servers vulnerable to
remote attack.

ISS issued a security bulletin Tuesday about a flaw in the NSS
library's implementation of the Secure Sockets Layer Version 2 (SSLv2)  
protocol that could allow remote attackers to use an SSLv2 connection
to take control of Web servers using the NSS library. The flaw in the
NSS library affects the Netscape Enterprise Server and Sun's Sun Java
System Web Server, but may also affect countless other products that
use the open source NSS library, ISS said.

The problem stems from a flaw in the way the NSS library handles
requests for new SSLv2 sessions. Servers using the NSS library do not
check the length of a record field in the first part of the
negotiation between two systems attempting to establish an SSLv2
session. Malicious hackers could use the absence of that length check
in the first record sent in the negotiation, known as the "hello
message," to cause a heap overflow, allowing them to place and run
malicious code on a vulnerable server, ISS said.

In heap overflows, an area of a vulnerable computer's memory that is
allocated for use by a software program is exceeded by a piece of data
that is larger than the allocated space, causing adjacent areas of
memory on the system to be overwritten with arbitrary data or
malicious code sent by the attacker.

If successfully exploited, the NSS library vulnerability gives a
remote attacker access to the vulnerable system with the same level of
privileges as those given to the Web server. On Microsoft Windows
systems, Web servers typically have full system privileges, ISS said.

While SSLv2 protocol support is disabled on the Netscape Enterprise
Server and Java System Web Server, SSLv2 is a commonly used protocol
for sending sensitive information over the Internet, and many
installations may have the support for SSLv2 enabled, ISS said.

In addition to the Sun Java System Web Server and Netscape Enterprise
Server, the flaw affects the Netscape Personalization Engine, Netscape
Director Server and Netscape Certificate Management Server, the
company said.

The Mozilla Foundation issued a patch for the NSS library that fixes
the SSLv2 hole. Alternatively, NetScape Enterprise users can disable
the SSLv2 protocol, ISS said.

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