USN-6439-1: Linux kernel vulnerabilities

It was discovered that the IPv6 implementation in the Linux kernel
contained a high rate of hash collisions in connection lookup table. A
remote attacker could use this to cause a denial of service (excessive CPU
consumption). (CVE-2023-1206)

Yu Hao and Weiteng Chen discovered that the Bluetooth HCI UART driver in
the Linux kernel contained a race condition, leading to a null pointer
dereference vulnerability. A local attacker could use this to cause a
denial of service (system crash). (CVE-2023-31083)

Ross Lagerwall discovered that the Xen netback backend driver in the Linux
kernel did not properly handle certain unusual packets from a
paravirtualized network frontend, leading to a buffer overflow. An attacker
in a guest VM could use this to cause a denial of service (host system
crash) or possibly execute arbitrary code. (CVE-2023-34319)

Lin Ma discovered that the Netlink Transformation (XFRM) subsystem in the
Linux kernel contained a null pointer dereference vulnerability in some
situations. A local privileged attacker could use this to cause a denial of
service (system crash). (CVE-2023-3772)

Kyle Zeng discovered that the networking stack implementation in the Linux
kernel did not properly validate skb object size in certain conditions. An
attacker could use this cause a denial of service (system crash) or
possibly execute arbitrary code. (CVE-2023-42752)

Kyle Zeng discovered that the netfiler subsystem in the Linux kernel did
not properly calculate array offsets, leading to a out-of-bounds write
vulnerability. A local user could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2023-42753)

Kyle Zeng discovered that the IPv4 Resource Reservation Protocol (RSVP)
classifier implementation in the Linux kernel contained an out-of-bounds
read vulnerability. A local attacker could use this to cause a denial of
service (system crash). Please note that kernel packet classifier support
for RSVP has been removed to resolve this vulnerability. (CVE-2023-42755)

Bing-Jhong Billy Jheng discovered that the Unix domain socket
implementation in the Linux kernel contained a race condition in certain
situations, leading to a use-after-free vulnerability. A local attacker
could use this to cause a denial of service (system crash) or possibly
execute arbitrary code. (CVE-2023-4622)

Budimir Markovic discovered that the qdisc implementation in the Linux
kernel did not properly validate inner classes, leading to a use-after-free
vulnerability. A local user could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2023-4623)

Alex Birnberg discovered that the netfilter subsystem in the Linux kernel
did not properly validate register length, leading to an out-of- bounds
write vulnerability. A local attacker could possibly use this to cause a
denial of service (system crash). (CVE-2023-4881)

It was discovered that the Quick Fair Queueing scheduler implementation in
the Linux kernel did not properly handle network packets in certain
conditions, leading to a use after free vulnerability. A local attacker
could use this to cause a denial of service (system crash) or possibly
execute arbitrary code. (CVE-2023-4921)

SecRule REQUEST_URI "@rx ..." "id:1001,phase:1,deny,status:403"

find /var/www -type f -name "*.php" -mmin -120

ss -tunp | grep -E ":(4444|1337|8080|9001)"

apt update && apt --only-upgrade install <pkg>

title: Detect Exploitation - USN-6439-1: Linux kernel vulnerabilities
id: 20e1067e-f54e-482f-be04-b8c2415f02d8
status: experimental
description: Automatisch generierte SIEM-Erkennungsregel basierend auf CTI Intelligence
references:
  - https://tsecurity.de/
author: iShareStuff CTI Automated Detection Engine
date: 2026-09-24
logsource:
  category: network_connection
  product: any
detection:
  selection:
      CommandLine|contains:
        - 'exploit'
  condition: selection
falsepositives:
  - Legitime administrative Zugriffe oder Penetrationstests
level: high
tags:
  - attack.initial_access

rule CTI_Threat_Indicator {
    meta:
        author = "iShareStuff CTI Automated Detection Engine"
        date = "2026-09-24"
        description = "YARA Signature for "
    strings:
        $str = "USN-6439-1: Linux kernel vulne" ascii wide
    condition:
        any of them
}

index=security sourcetype IN ("cisco:asa", "pan:traffic", "zeek_conn", "suricata", "WinEventLog:Security")
("USN-6439-1 Linux kernel vulnerabilities")
| stats count earliest(_time) as first_seen latest(_time) as last_seen by src_ip, dest_ip, dest_host, signature
| eval first_seen=strftime(first_seen, "%Y-%m-%d %H:%M:%S"), last_seen=strftime(last_seen, "%Y-%m-%d %H:%M:%S")
| sort - count

message: "*USN-6439-1 Linux kernel vulnerabilities*"

CommonSecurityLog
| where Message has "USN-6439-1 Linux kernel vulnerabilities"
| summarize EventCount = count(), FirstSeen = min(TimeGenerated), LastSeen = max(TimeGenerated) by SourceIP, DestinationIP, DestinationPort, Activity
| extend DetectionRule = "iShareStuff-CTI-Compiled"
| sort by EventCount desc

#!/usr/sbin/nft -f
# ISS-ZeroTrust Quarantine Policy for CVE-2023-1206
table inet iss_quarantine {
    chain inbound_lockdown {
        type filter hook input priority -10; policy drop;

        # Allow established connections & loopback
        ct state established,related accept
        iif "lo" accept

        # Whitelist SOC / Bastion Management Subnet
        ip saddr 10.0.0.0/8 accept
        ip saddr 192.168.1.0/24 accept

        # Explicitly log & drop vulnerable service traffic
        tcp dport 443 log prefix "[ISS-QUARANTINE-CVE-2023-1206] " drop
    }
}

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: quarantine-CVE-2023-1206
  namespace: production
  labels:
    security.isharestuff.com/quarantine: "true"
    cve.mitigation/id: "CVE-2023-1206"
spec:
  podSelector:
    matchLabels:
      app.kubernetes.io/vulnerable-cve: "CVE-2023-1206"
  policyTypes:
    - Ingress
    - Egress
  ingress:
    # Restrict ingress solely to authorized security scanners & bastion pods
    - from:
        - namespaceSelector:
            matchLabels:
              kubernetes.io/metadata.name: soc-monitoring
      ports:
      - port: 443
        protocol: TCP
  egress:
    # Allow DNS only (isolate lateral movement)
    - to:
        - namespaceSelector: {}
          podSelector:
            matchLabels:
              k8s-app: kube-dns
      ports:
        - port: 53
          protocol: UDP

aws ec2 revoke-security-group-ingress --group-id sg-0123456789abcdef0 --protocol tcp --port 443 --cidr 0.0.0.0/0

(http.request.uri.path contains "CVE-2023-1206" or http.request.body.mime contains "exploit" or cf.threat_score gt 20)