Detect CVE-2025-20393 — Cisco Multiple Products Improper Input Validation (KEV) in Google Chronicle
Detects exploitation attempts targeting CVE-2025-20393, an improper input validation vulnerability (CWE-20) affecting Cisco Multiple Products. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active in-the-wild exploitation. Attackers may leverage this flaw to bypass security controls, execute unauthorized commands, or gain elevated access to affected Cisco appliances.
MITRE ATT&CK
YARA-L Detection Query
rule cve_2025_20393_cisco_input_validation {
meta:
author = "df00tech"
description = "Detects CVE-2025-20393 exploitation — Cisco improper input validation"
severity = "HIGH"
priority = "HIGH"
reference = "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-attack-N9bf4"
events:
$e.metadata.event_type = "NETWORK_HTTP"
$e.target.application = /(?i)cisco/
(
$e.network.http.request_url = /(\.\.\/|%2e%2e%2f|%252e|;|%00)/
or $e.metadata.description = /(?i)(input validation|malformed|invalid input)/
)
$src_ip = $e.principal.ip
match:
$src_ip over 5m
outcome:
$event_count = count_distinct($e.metadata.id)
$target_hosts = array_distinct($e.target.hostname)
condition:
#e > 2
}Chronicle YARA-L rule detecting repeated suspicious HTTP requests to Cisco products containing path traversal or input injection patterns from the same source IP within 5 minutes.
Data Sources
Required Tables
False Positives & Tuning
- Authorized red team exercises targeting Cisco infrastructure
- Cisco Smart Software Manager or licensing services using encoded callback URLs
- Third-party ITSM integrations with non-standard character handling in Cisco API requests
Other platforms for CVE-2025-20393
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Path Traversal Probe Against Cisco SMA Interface
Expected signal: HTTP request log entry with URI containing '../' sequences recorded in Cisco SMA access log; network flow record from test host to Cisco appliance on port 443
- Test 2Null Byte Injection Input Validation Test
Expected signal: HTTP request containing '%00' in query string logged by network proxy or Cisco appliance; potential error response indicating input validation failure
- Test 3Automated Exploitation Pattern Simulation with Repeated Requests
Expected signal: Ten sequential HTTP requests with encoded path traversal sequences from same source IP within 10 seconds, logged across Cisco access logs and network flow telemetry
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