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Mallory
HighCISA KEVExploited in the wildPublic exploit

Cisco ASA and FTD Web Services Denial of Service Vulnerability

IdentifiersCVE-2024-20353CWE-20

CVE-2024-20353 is a denial-of-service vulnerability in the management and VPN web servers of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software. The flaw is caused by incomplete error checking while parsing an HTTP header. An unauthenticated remote attacker can trigger the issue by sending a crafted HTTP request to a targeted management or VPN web interface. Successful exploitation causes the affected device to reload unexpectedly, producing a denial-of-service condition. Cisco and multiple reporting sources also associate this CVE with the ArcaneDoor intrusion activity, where attackers reportedly used the forced reboot behavior to facilitate deployment of additional malware components on compromised devices.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an unauthenticated remote attacker to remotely crash and reload the affected ASA or FTD device, causing denial of service against management and/or VPN web services and potentially broader disruption of firewall and remote-access availability during the reload. Reporting tied to ArcaneDoor indicates the reboot behavior was also operationally useful to attackers in at least some intrusions because it could facilitate installation of follow-on malware components during device restart.

Mitigation

If you can’t patch tonight, do this now.

No workaround is available according to the provided advisory context. Until patching is completed, reduce exposure of management and VPN web interfaces to untrusted networks where operationally possible, closely monitor for unscheduled reboots, anomalous web/VPN activity, undocumented configuration changes, and suspicious credential activity, and follow Cisco/Talos incident-response guidance if compromise is suspected.

Remediation

Patch, then assume compromise.

Apply Cisco-provided fixed software updates for affected ASA and FTD releases. The content identifies fixed ASA releases including 9.12.4.67, 9.16.4.57, 9.18.4.22, 9.19.1.28, and 9.20.2.10, and fixed FTD releases including 7.0.6.2, 7.2.6, and 7.4.1.1, depending on the deployed train. Use Cisco's Software Checker and the advisory cisco-sa-asaftd-websrvs-dos-X8gNucD2 to determine the correct fixed version for the specific platform and upgrade promptly.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Cisco SystemsAdaptive Security Appliance Softwareoperating_system
Cisco SystemsAsaapplication
Cisco SystemsFirepower Threat Defenseapplication
Cisco SystemsFirepower Threat Defense Softwareapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

28 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence7

Every observed campaign linking this CVE to a named adversary.

Associated malware8

Malware families riding this exploit, with evidence and IOCs.

Detection signatures1

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity6

Community discussion across Reddit, Mastodon, and other social sources.