Title: Sun Java Runtime Environment InitialDirContext Remote Denial Of Service Vulnerability
Severity: MODERATE
Description:
A remote denial of service vulnerability reportedly affects the Sun Java Runtime Environment. This issue is due to a design error that fails to keep track of DNS requests.
The problem presents itself when a network-based application running on the affected Java Runtime Environment makes an excessive number of DNS requests. Apparently the Java Runtime Environment uses the 'InitialDirContext' object to process DNS requests, which fails to properly handle DNS request IDs due to a variable casting error.
The affected object stores the DNS ID in a type 'int' variable, named 'xid', that is cast as a 'short' 'ident'; this variable will be treated as a signed 'short' type and so will wrap after 32768 requests are made. Once 32768 requests are made the counter will wrap around to equal -32768.
Subsequently the 'InitialDirContext' employs the 'Header' class to process the answer from the DNS server, which returns an 'int' for the request ID that will not wrap. This causes the DNS request to fail as the two IDs are later checked for a match, and due to the type cast issue they will not.
An attacker may leverage this issue to cause an application running on the affected software to fail to make DNS requests, causing a denial of service condition on network-based Java applications.
Although Sun's Java Runtime Environment version 1.4.2 and 1.5.0 are reportedly affected, it is likely that earlier versions are affected as well.
Reports from Harry Johnston indicate the OraClient 10g component of Oracle Database Server 10g incorporates a vulnerable version of the Java Runtime Environment and is therefore vulnerable to this issue.
Affected Products:
- Oracle Oracle10g Application Server 10.1.0 .0.2
- Oracle Oracle10g Enterprise Edition 10.1.0 .0.2
- Oracle Oracle10g Personal Edition 10.1.0 .0.2
- Oracle Oracle10g Standard Edition 10.1.0 .0.2
- Sun Java 2 Runtime Environment 1.4.2
- Sun Java 2 Runtime Environment 1.4.2_03
- Sun Java 2 Runtime Environment 1.5.0
References:
- Sun: Java Homepage
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