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F5 Networks BIG-IP : IPv6 fragmentation vulnerability (K57211290)
high Nessus Plugin ID 101493
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Synopsis
The remote device is missing a vendor-supplied security patch.Description
An issue was discovered in the IPv6 protocol specification, related to ICMP Packet Too Big (PTB) messages. (The scope of this CVE is all affected IPv6 implementations from all vendors.) The security implications of IP fragmentation have been discussed at length in [RFC6274] and [RFC7739]. An attacker can leverage the generation of IPv6 atomic fragments to trigger the use of fragmentation in an arbitrary IPv6 flow (in scenarios in which actual fragmentation of packets is not needed) and can subsequently perform any type of fragmentation-based attack against legacy IPv6 nodes that do not implement [RFC6946]. That is, employing fragmentation where not actually needed allows for fragmentation-based attack vectors to be employed, unnecessarily. We note that, unfortunately, even nodes that already implement [RFC6946] can be subject to DoS attacks as a result of the generation of IPv6 atomic fragments. Let us assume that Host A is communicating with Host B and that, as a result of the widespread dropping of IPv6 packets that contain extension headers (including fragmentation) [RFC7872], some intermediate node filters fragments between Host B and Host A. If an attacker sends a forged ICMPv6 PTB error message to Host B, reporting an MTU smaller than 1280, this will trigger the generation of IPv6 atomic fragments from that moment on (as required by [RFC2460]). When Host B starts sending IPv6 atomic fragments (in response to the received ICMPv6 PTB error message), these packets will be dropped, since we previously noted that IPv6 packets with extension headers were being dropped between Host B and Host A. Thus, this situation will result in a DoS scenario. Another possible scenario is that in which two BGP peers are employing IPv6 transport and they implement Access Control Lists (ACLs) to drop IPv6 fragments (to avoid control-plane attacks). If the aforementioned BGP peers drop IPv6 fragments but still honor received ICMPv6 PTB error messages, an attacker could easily attack the corresponding peering session by simply sending an ICMPv6 PTB message with a reported MTU smaller than 1280 bytes. Once the attack packet has been sent, the aforementioned routers will themselves be the ones dropping their own traffic. (CVE-2016-10142)Solution
Upgrade to one of the non-vulnerable versions listed in the F5 Solution K57211290.See Also
Plugin Details
Severity: High
ID: 101493
File Name: f5_bigip_SOL57211290.nasl
Version: 3.13
Type: local
Published: 7/13/2017
Updated: 3/9/2020
Supported Sensors: Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 4.4
CVSS v2
Risk Factor: Medium
Base Score: 5
Temporal Score: 3.7
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P
CVSS v3
Risk Factor: High
Base Score: 8.6
Temporal Score: 7.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
Vulnerability Information
CPE: cpe:/a:f5:big-ip_access_policy_manager, cpe:/a:f5:big-ip_advanced_firewall_manager, cpe:/a:f5:big-ip_application_acceleration_manager, cpe:/a:f5:big-ip_application_security_manager, cpe:/a:f5:big-ip_application_visibility_and_reporting, cpe:/a:f5:big-ip_global_traffic_manager, cpe:/a:f5:big-ip_link_controller, cpe:/a:f5:big-ip_local_traffic_manager, cpe:/a:f5:big-ip_policy_enforcement_manager, cpe:/a:f5:big-ip_webaccelerator, cpe:/h:f5:big-ip, cpe:/h:f5:big-ip_protocol_security_manager
Required KB Items: Host/local_checks_enabled, Host/BIG-IP/hotfix, Host/BIG-IP/modules, Host/BIG-IP/version
Exploit Ease: No known exploits are available
Patch Publication Date: 7/12/2017
Vulnerability Publication Date: 1/14/2017
Reference Information
CVE: CVE-2016-10142