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Rule:
--
Sid:
2033
--
Summary:
A request has been made to rpc.ypserv from an external source that
should not have access to this service. This may be indicative of an
intelligence gathering activity as a prelude to a more serious
compromise of system resources.
service against the target host.
--
Impact:
Disclosure of sensitive system information to an unauthorized user.
Possible denial of service.
--
Detailed Information:
The rpc.ypserv daemon queries information in the local NIS maps. A
response to this query may divulge important information to the user
performing the query. This could lead to futher exploitation of
resources on the network.
In addition, a vulnerability exists in ypserv on some Linux platforms
that could lead to a buffer overflow and root compromise of the target
host. This is achieved by making a multitude of requests for a NIS map
that does not exist.
--
Affected Systems:
Multiple systems running versions of ypserv prior to 2.5.
--
Attack Scenarios:
The attacker can craft a malicious request to rpc.ypserv such that
valuable information can be returned to the attacker.
In the case of a buffer overflow, the attacker might issue a large
therefore, be seen many times.
--
Ease of Attack:
Simple
--
False Positives:
None Known
--
False Negatives:
None Known
--
Corrective Action:
Disallow all RPC requests from external sources and use a firewall to
block access to RPC ports from outside the LAN.
Upgrade ypserv to the latest version.
Use /var/yp/securenets to list the hosts allowed to access this resource
where appropriate.
--
Contributors:
Sourcefire Research Team
Brian Caswell <bmc@sourcefire.com>
Nigel Houghton <nigel.houghton@sourcefire.com>
--
Additional References:
Bugtraq:
http://www.securityfocus.com/bid/6016
http://www.securityfocus.com/bid/5914
CVE:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2002-1232
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2000-1043
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2000-1042
--
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