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CERT Coordination Center

NTP service vulnerable to internal overflow if date / time offset is greater than 34 years

Vulnerability Note VU#584606

Original Release Date: 2004-03-05 | Last Revised: 2004-03-05

Overview

NTP (Network TIme Protocol) contains an integer overflow vulnerability that may lead to clients receiving an incorrect date/time offset.

Description

NTP (Network Time Protocol) is a method by which client machines can synchronize the local date and time with a reference server. The server will miscalculate the offset reply, if it receives a request from an NTP client containing a date that is more or less than 34 years of the server's date.

This offset is a 64-bit value, with 32 bits representing whole seconds, and 32 bits representing fractions of a second . The 34-year limit is imposed by the use of a 32-bit signed integer.

The NTP server performs a series of calculations, accounting for transmission delay and computing time, resulting in a value which represents the difference between the NTP server time and the requesting machine's time.

The packet sent back to the client is a date/time offset, which is then used to update the client's date/time.

Impact

Clients making requests of an NTP server and supplying a date/time that is more than 34 years in the future (or past) from the NTP server date/time will receive an incorrect date/time offset from the server, resulting in an incorrect date/time on the client.


There is no known impact to the NTP server.

Solution

NTPd Version 4 resolves this issue.

Vendor Information

584606
 
Affected   Unknown   Unaffected

NTP.org

Updated:  March 05, 2004

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.


CVSS Metrics

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A

References

Credit

Thanks to David L. Mills of NTP.org for reporting this vulnerability.

This document was written by Robert D Hanson.

Other Information

CVE IDs: None
Severity Metric: 0.06
Date Public: 2004-01-22
Date First Published: 2004-03-05
Date Last Updated: 2004-03-05 19:06 UTC
Document Revision: 5

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