Denial of Service (DoS) in Splunk Enterprise Using a Malformed SAML Request
Advisory ID: SVD-2023-0802
CVE ID: CVE-2023-40593
Published: 2023-08-30
Last Update: 2023-10-18
CVSSv3.1 Score: 6.3, Medium
CVSSv3.1 Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H
CWE: CWE-400
Bug ID: SPL-219455
Description
In Splunk Enterprise versions lower than 9.0.6, and 8.2.12, an attacker can send a malformed security assertion markup language (SAML) request to the /saml/acs
REST endpoint which can cause a denial of service through a crash or hang of the Splunk daemon.
The SAML extensible markup language (XML) parser does not fail SAML signature validation when the attacker modifies the URI in the SAML request. Instead it attempts to access the modified URI, which causes the Splunk daemon to crash or hang.
Solution
Upgrade Splunk Enterprise to versions 8.2.12 and 9.0.6. This vulnerability does not affect Splunk Enterprise versions 9.1.0 and higher.
Splunk is actively monitoring and patching Splunk Cloud Platform instances.
Product Status
Product | Version | Component | Affected Version | Fix Version |
---|---|---|---|---|
Splunk Enterprise | 8.2 | Splunk Web | 8.2.0 to 8.2.11 | 8.2.12 |
Splunk Enterprise | 9.0 | Splunk Web | 9.0.0 to 9.0.5 | 9.0.6 |
Splunk Cloud | - | Splunk Web | 8.2.2203 | 9.0.2205 |
Mitigations and Workarounds
Disable single sign-on using SAML as an authentication scheme (SAML SSO). For more information on this type of configuration, see Configure single sign-on with SAML in the Splunk documentation.
Detections
Severity
Splunk rates this vulnerability as 6.3, Medium, with a CVSSv3.1 vector of CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H.
If your Splunk Enterprise Instance does not use SAML as an authentication scheme for SSO, it is not affected and this vulnerability can be considered informational.
Acknowledgments
Aaron Devaney (Dodekeract)
Changelog
- 2023-10-18: Added additional mitigations and specified that if your installation does not run SAML for SSO, this vulnerability can be considered informational