First published: Wed Aug 03 2016(Updated: )
The busybox NTP implementation doesn't check the NTP mode of packets received on the server port and responds to any packet with the right size. This includes responses from another NTP server. An attacker can send a packet with a spoofed source address in order to create an infinite loop of responses between two busybox NTP servers. Adding more packets to the loop increases the traffic between the servers until one of them has a fully loaded CPU and/or network. It seems this bug was actually inherited from openntpd, on which the busybox implementation was based on. In openntpd it was fixed in: <a href="https://github.com/openntpd-portable/openntpd-openbsd/commit/28a2f904aafbf4c209fe6fa04ffb9308740fd78a">https://github.com/openntpd-portable/openntpd-openbsd/commit/28a2f904aafbf4c209fe6fa04ffb9308740fd78a</a> Busybox upstream patch: <a href="https://git.busybox.net/busybox/commit/?id=150dc7a2b483b8338a3e185c478b4b23ee884e71">https://git.busybox.net/busybox/commit/?id=150dc7a2b483b8338a3e185c478b4b23ee884e71</a>
Affected Software | Affected Version | How to fix |
---|---|---|
Ubuntu BusyBox Static | ||
Openntpd Openntpd |
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The severity of REDHAT-BUG-1363710 is considered high due to the potential for an attacker to create an infinite loop of responses.
To fix REDHAT-BUG-1363710, you need to update to the patched versions of BusyBox and OpenNTPD that address the vulnerability.
Affected systems include BusyBox and OpenNTPD implementations that do not properly verify the mode of NTP packets.
The exploit technique involves sending a NTP packet with a spoofed source address to trigger a response loop.
A known workaround for REDHAT-BUG-1363710 is to configure firewall rules to restrict NTP traffic from untrusted sources.