cbcvebase.
CVE-2013-5211
published 2014-01-02

CVE-2013-5211: The monlist feature in ntp_request.c in ntpd in NTP before 4.2.7p26 allows remote attackers to cause a denial of service (traffic amplification) via forged (1)…

PriorityP271medium5CVSS 2.0
AVNACLAuNCNINAP
ITWEXPLOITVulnCheck KEV
Exploited in the wild
EPSS
97.76%
99.9th percentile
The monlist feature in ntp_request.c in ntpd in NTP before 4.2.7p26 allows remote attackers to cause a denial of service (traffic amplification) via forged (1) REQ_MON_GETLIST or (2) REQ_MON_GETLIST_1 requests, as exploited in the wild in December 2013.

Affected

7 ranges
VendorProductVersion rangeFixed in
debianntp< ntp 1:4.2.8p3+dfsg-1 (bullseye)ntp 1:4.2.8p3+dfsg-1 (bullseye)
ntpntp< 4.2.74.2.7
ntpntp
ntpntp>= 0 < 1:4.2.8p3+dfsg-11:4.2.8p3+dfsg-1
opensuseopensuse
oraclelinux
oraclelinux

Detection & IOCsextracted from sources · hover to see the quote

portUDP/123
commandREQ_MON_GETLIST
otherNTP.Monlist.Command.DoS
bytes
rm_vn_mode=0x17; implementation=0x03; request=0x2a
  • Detect NTP monlist (REQ_MON_GETLIST) abuse by inspecting UDP/123 packets with NTP mode 7 (rm_vn_mode=0x17), implementation byte 0x03, and request byte 0x2a (decimal 42).
  • Flag NTP servers responding to 'monlist' queries; the more clients in the list, the greater the amplification factor for DRDoS attacks.
  • Alert on NTP mode 7 PEER_LIST responses that are larger in size or greater in quantity than the originating request, indicative of DRDoS amplification.
  • Detect NTP mode 7 GET_RESTRICT (reslist) queries on UDP/123; responses revealing restriction lists can be abused for traffic amplification DRDoS.
  • Detect NTP mode 6 UNSETTRAP requests; in some configurations servers respond with multiple packets, enabling DRDoS amplification via spoofed source IPs.
  • ·Vulnerability affects NTP versions before 4.2.7p26; upgrade to 4.2.7p26 or later to disable the monlist feature by default.
  • ·The attack exploits IP spoofing to reflect/amplify traffic; ingress filtering (BCP38) on network perimeters reduces the effectiveness of spoofed-source NTP amplification attacks.

CVSS provenance

nvdv2.05.0MEDIUMAV:N/AC:L/Au:N/C:N/I:N/A:P
osv5.0MEDIUM
vulncheck5.0MEDIUM
vendor_cisco5.0MEDIUM
vendor_debian5.0LOW
vendor_redhat5.0MEDIUM
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