CVE-2018-7182

What it actually does

Out-of-bounds read in ntpd ctl_getitem triggered by crafted NTP mode 6 packets, resulting in denial of service.

Why it matters to the business

Disruption of time synchronization services can cascade into failures for logging, authentication, certificate validation, and scheduled operations across affected systems.

How an attack unfolds

An attacker sends a specially crafted NTP mode 6 packet to a vulnerable ntpd instance (4.2.8p6 through 4.2.8p10); the ctl_getitem function performs an out-of-bounds read that crashes the daemon. Public exploit code exists and the vulnerability has remained stable in exploitation probability.

How to fix it

Upgrade ntpd to 4.2.8p11 or later; restrict mode 6 control queries via configuration (restrict ... noquery) where upgrades are delayed.

How to confirm the fix worked

Verify ntpd version is 4.2.8p11 or newer; confirm mode 6 query restrictions in ntp.conf; test connectivity with legitimate mode 6 tools after patching.

Typical attack path

1. Identify reachable ntpd instances responding to mode 6 queries
2. Transmit crafted mode 6 packet targeting ctl_getitem
3. Trigger out-of-bounds memory read
4. Cause ntpd crash or unavailability

How to detect it

Review ntpd logs for unexpected restarts or crashes around mode 6 handling; inspect network captures for atypical mode 6 packets; correlate with exploit maturity indicators.

• ctl_getitem
• mode 6 packet
• ntpd.*4\.2\.8p[6-9]|4\.2\.8p10

What your security team should do

• Prioritize upgrade of all ntpd instances to 4.2.8p11 or newer
• Apply network-level restrictions on UDP 123 for mode 6 traffic
• Monitor for ntpd restarts and anomalous mode 6 packets
• Replace NTP with a maintained alternative where feasible