Denial of service in FreeBSD

1) Resource exhaustion

EUVDB-ID: #VU14203

Risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2018-6922

CWE-ID: CWE-400 - Resource exhaustion

Exploit availability: No

Description

The vulnerability allows a remote attacker to cause DoS condition on the target system.

The vulnerability exists due to the system uses an inefficient TCP reassembly algorithm. A remote attacker can send specially crafted packets within ongoing TCP sessions to consume excessive CPU resources and cause the service to crash.

Mitigation

As a workaround, system administrators should configure their systems to only accept TCP connections from trusted end-stations, if it is possible to do so.

For systems which must accept TCP connections from untrusted end-stations, the workaround is to limit the size of each reassembly queue. The capability to do that is added by the patches noted in the "Solution" section below.

Vulnerable software versions

FreeBSD: 5.3 - 11.1

CPE2.3

• cpe:2.3:o:freebsd_foundation:freebsd:5.3:*:*:*:*:*:*:*
• cpe:2.3:o:freebsd_foundation:freebsd:5.4:*:*:*:*:*:*:*
• cpe:2.3:o:freebsd_foundation:freebsd:5.5:*:*:*:*:*:*:*

External links

https://www.freebsd.org/security/advisories/FreeBSD-SA-18:08.tcp.asc

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.