cbcvebase.
CVE-2021-24074
published 2021-02-25

CVE-2021-24074: Windows TCP/IP Remote Code Execution Vulnerability

PriorityP272critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
25.71%
97.7th percentile
Windows TCP/IP Remote Code Execution Vulnerability

Affected

45 ranges· showing 25
VendorProductVersion rangeFixed in
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10
microsoftwindows_10_version_1507>= 10.0.0 < publicationpublication
microsoftwindows_10_version_1607>= 10.0.0 < publicationpublication
microsoftwindows_10_version_1803>= 10.0.0 < publicationpublication
microsoftwindows_10_version_1809>= 10.0.0 < publicationpublication
microsoftwindows_10_version_1909>= 10.0.0 < publicationpublication
microsoftwindows_10_version_2004>= 10.0.0 < publicationpublication
microsoftwindows_10_version_20h2>= 10.0.0 < publicationpublication
microsoftwindows_7>= 6.1.0 < publicationpublication
microsoftwindows_7_service_pack_1>= 6.1.0 < publicationpublication
microsoftwindows_8.1>= 6.3.0 < publicationpublication
microsoftwindows_server_2008
microsoftwindows_server_2008_r2_service_pack_1>= 6.0.0 < publicationpublication
microsoftwindows_server_2008_r2_service_pack_1>= 6.1.0 < publicationpublication
microsoftwindows_server_2008_service_pack_2>= 6.0.0 < publicationpublication
microsoftwindows_server_2012
microsoftwindows_server_2012>= 6.2.0 < publicationpublication
microsoftwindows_server_2012_r2>= 6.3.0 < publicationpublication
microsoftwindows_server_2016
microsoftwindows_server_2016

Detection & IOCsextracted from sources · hover to see the quote

commandnetsh int ipv4 set global sourceroutingbehavior=drop
commandnetsh int ipv6 set global reassemblylimit=0
snort
57103, 57104, 57106 - 57108, 57123 and 57128
  • CVE-2021-24074 is triggered by two IPv4 fragments where the first has the Security Options (Type 130) field, followed by a second fragment with either the Loose Source and Record Route (LSRR) option (Type 131) or the Strict Source and Record Route (SSRR) option (Type 137). Detect/block IPv4 packets carrying LSRR or SSRR options.
  • Monitor/drop IPv4 packets with Malformed, Strict Source Routing, and Loose Source Routing IP options at the network perimeter; these are the specific packet types used to exploit CVE-2021-24074.
  • Use PAN-OS flow counters flow_dos_pf_badoption, flow_dos_pf_strictsource to detect IPv4 packets being dropped due to malformed or source-routing options associated with CVE-2021-24074 exploitation attempts.
  • The exploit involves out-of-bound read and write during reassembly of IP fragments with confused options fields; network sensors should flag fragmented IPv4 traffic carrying source routing options.
  • ·The workaround command 'netsh int ipv4 set global sourceroutingbehavior=drop' causes the system to drop source routing requests entirely without processing; default Windows behavior is 'dontforward' which still processes and returns an ICMP denial. Changing this may affect legitimate traffic that relies on source routing responses.
  • ·The IPv6 reassembly limit workaround (reassemblylimit=0) drops all out-of-order packets and may cause packet loss in environments with legitimate fragmented IPv6 traffic; testing before production deployment is recommended.
  • ·Host-based firewalls do not provide sufficient protection for the related IPv6 DoS vulnerability (CVE-2021-24086); an edge device such as a firewall or load balancer must be used to block IPv6 fragmentation.
  • ·Snort rules 57103, 57104, 57106-57108, 57123, and 57128 cover multiple February 2021 Patch Tuesday vulnerabilities collectively, not exclusively CVE-2021-24074; additional rules may be released and current rules are subject to change.

CVSS provenance

nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv2.07.5HIGHAV:N/AC:L/Au:N/C:P/I:P/A:P
vendor_msrc9.8CRITICAL
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