Today we are releasing Grafana 7.5.11, and 8.1.6. These patch releases include an important security fix for an issue that affects all Grafana versions from 2.0.1.
Grafana Cloud instances have already been patched and an audit did not find any usage of this attack vector. Grafana Enterprise customers were provided with updated binaries under embargo.
8.1.5 contained a single fix for bar chart panels. We believe that users can expedite deployment by moving from 8.1.4 to 8.1.6 directly.
CVE-2021-39226 Snapshot authentication bypass
Summary
CVSS Score: 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
We received a security report to security@grafana.com on 2021-09-15 about a vulnerability in Grafana regarding the snapshot feature. It was later identified as affecting Grafana versions from 2.0.1 to 8.1.6. CVE-2021-39226 has been assigned to this vulnerability.
Impact
Unauthenticated and authenticated users are able to view the snapshot with the lowest database key by accessing the literal paths:
/dashboard/snapshot/:key, or/api/snapshots/:key
If the snapshot "public_mode" configuration setting is set to true (vs default of false), unauthenticated users are able to delete the snapshot with the lowest database key by accessing the literal path:
/api/snapshots-delete/:deleteKey
Regardless of the snapshot "public_mode" setting, authenticated users are able to delete the snapshot with the lowest database key by accessing the literal paths:
/api/snapshots/:key, or/api/snapshots-delete/:deleteKey
The combination of deletion and viewing enables a complete walk through all snapshot data while resulting in complete snapshot data loss.
Attack audit
While we can not guarantee that the below will identify all attacks, if you do find something with the below, you should consider doing a full assessment.
Through reverse proxy/load balancer logs
To determine if your Grafana installation has been exploited for this vulnerability, search through your reverse proxy/load balancer access logs for instances where the path is /dashboard/snapshot/:key, /api/snapshots/:key or /api/snapshots-delete/:deleteKey, and the response status code was 200 (OK).
For example, if you’re using the Kubernetes ingress-nginx controller and sending logs to Loki, use a LogQL query like {job="nginx-ingress-controller"} |= "\"status\": 200" |= "\"uri\": \"/api/snapshots/:key\"".
Through the Grafana Enterprise audit feature
If you enabled “Log web requests” in your configuration with router_logging = true, look for
"requestUri":"/api/snapshots-delete/”,“requestUri":"/api/snapshots/:key", or "type":"snapshot" in combination with "action":"delete".
Patched versions
Release 8.1.6:
Release 7.5.11:
Solutions and mitigations
Download and install the appropriate patch for your version of Grafana.
Grafana Cloud instances have already been patched, and Grafana Enterprise customers were provided with updated binaries under embargo.
Workaround
If for some reason you cannot upgrade:
You can use a reverse proxy or similar to block access to the literal paths
/api/snapshots/:key/api/snapshots-delete/:deleteKey/dashboard/snapshot/:key/api/snapshots/:key
They have no normal function and can be disabled without side effects.
Timeline and postmortem
Here is a detailed timeline starting from when we originally learned of the issue. All times in UTC.
- 2021-09-15 14:49: Tuan Tran theblackturtle0901@gmail.com sends initial report about viewing snapshots without authentication
- 2021-09-15 15:56: Initial reproduction
- 2021-09-15 17:10: MEDIUM severity declared
- 2021-09-15 18:58: Workaround deployed on Grafana Cloud
- 2021-09-15 19:15:
/api/snapshots/:key found to be vulnerable as well
- 2021-09-15 19:30:
/api/snapshots/:key blocked on Grafana Cloud
- 2021-09-16 09:31:
/api/snapshots-delete/:deleteKey found to be vulnerable as well, blocked on Grafana Cloud. From this point forward, Cloud is not affected any more.
- 2021-09-16 09:35: HIGH severity declared
- 2021-09-16 11:19: Realization that combination of deletion and viewing allows enumeration and permanent DoS
- 2021-09-16 11:19: CRITICAL declared
- 2021-09-17 10:53: Determination that no weekend work is needed. While issue is CRITICAL, scope is very limited
- 2021-09-17 14:26: Audit of Grafana Cloud concluded, no evidence of exploitation
- 2021-09-23: Grafana Cloud instances updated
- 2021-09-28 12:00: Grafana Enterprise images released to customers under embargo
- 2021-10-05 17:00: Public release
Reporting security issues
If you think you have found a security vulnerability, please send a report to security@grafana.com. This address can be used for all of
Grafana Labs's open source and commercial products (including but not limited to Grafana, Tempo, Loki, Amixr, k6, Tanka, and Grafana Cloud, Grafana Enterprise, and grafana.com). We only accept vulnerability reports at this address. We would prefer that you encrypt your message to us using our PGP key. The key fingerprint is:
F988 7BEA 027A 049F AE8E 5CAA D125 8932 BE24 C5CA
The key is available from keys.gnupg.net by searching for [security@grafana](http://keys.gnupg.net/pks/lookup?search=security@grafana&fingerprint=on&op=index.
Security announcements
We maintain a category on the community site named Security Announcements,
where we will post a summary, remediation, and mitigation details for any patch containing security fixes. You can also subscribe to email updates to this category if you have a grafana.com account and sign in to the community site, or via updates from our Security Announcements RSS feed.
Acknowledgement
We would like to thank Tran Viet Tuan for responsibly disclosing the initially discovered vulnerability to us.
References
theblackturtle Analyst
Today we are releasing Grafana 7.5.11, and 8.1.6. These patch releases include an important security fix for an issue that affects all Grafana versions from 2.0.1.
Grafana Cloud instances have already been patched and an audit did not find any usage of this attack vector. Grafana Enterprise customers were provided with updated binaries under embargo.
8.1.5 contained a single fix for bar chart panels. We believe that users can expedite deployment by moving from 8.1.4 to 8.1.6 directly.
CVE-2021-39226 Snapshot authentication bypass
Summary
CVSS Score: 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
We received a security report to security@grafana.com on 2021-09-15 about a vulnerability in Grafana regarding the snapshot feature. It was later identified as affecting Grafana versions from 2.0.1 to 8.1.6. CVE-2021-39226 has been assigned to this vulnerability.
Impact
Unauthenticated and authenticated users are able to view the snapshot with the lowest database key by accessing the literal paths:
/dashboard/snapshot/:key, or/api/snapshots/:keyIf the snapshot "public_mode" configuration setting is set to true (vs default of false), unauthenticated users are able to delete the snapshot with the lowest database key by accessing the literal path:
/api/snapshots-delete/:deleteKeyRegardless of the snapshot "public_mode" setting, authenticated users are able to delete the snapshot with the lowest database key by accessing the literal paths:
/api/snapshots/:key, or/api/snapshots-delete/:deleteKeyThe combination of deletion and viewing enables a complete walk through all snapshot data while resulting in complete snapshot data loss.
Attack audit
While we can not guarantee that the below will identify all attacks, if you do find something with the below, you should consider doing a full assessment.
Through reverse proxy/load balancer logs
To determine if your Grafana installation has been exploited for this vulnerability, search through your reverse proxy/load balancer access logs for instances where the path is
/dashboard/snapshot/:key,/api/snapshots/:keyor/api/snapshots-delete/:deleteKey, and the response status code was 200 (OK).For example, if you’re using the Kubernetes ingress-nginx controller and sending logs to Loki, use a LogQL query like
{job="nginx-ingress-controller"} |= "\"status\": 200" |= "\"uri\": \"/api/snapshots/:key\"".Through the Grafana Enterprise audit feature
If you enabled “Log web requests” in your configuration with
router_logging = true, look for"requestUri":"/api/snapshots-delete/”,“requestUri":"/api/snapshots/:key", or"type":"snapshot"in combination with"action":"delete".Patched versions
Release 8.1.6:
Release 7.5.11:
Solutions and mitigations
Download and install the appropriate patch for your version of Grafana.
Grafana Cloud instances have already been patched, and Grafana Enterprise customers were provided with updated binaries under embargo.
Workaround
If for some reason you cannot upgrade:
You can use a reverse proxy or similar to block access to the literal paths
/api/snapshots/:key/api/snapshots-delete/:deleteKey/dashboard/snapshot/:key/api/snapshots/:keyThey have no normal function and can be disabled without side effects.
Timeline and postmortem
Here is a detailed timeline starting from when we originally learned of the issue. All times in UTC.
/api/snapshots/:keyfound to be vulnerable as well/api/snapshots/:keyblocked on Grafana Cloud/api/snapshots-delete/:deleteKeyfound to be vulnerable as well, blocked on Grafana Cloud. From this point forward, Cloud is not affected any more.Reporting security issues
If you think you have found a security vulnerability, please send a report to security@grafana.com. This address can be used for all of
Grafana Labs's open source and commercial products (including but not limited to Grafana, Tempo, Loki, Amixr, k6, Tanka, and Grafana Cloud, Grafana Enterprise, and grafana.com). We only accept vulnerability reports at this address. We would prefer that you encrypt your message to us using our PGP key. The key fingerprint is:
F988 7BEA 027A 049F AE8E 5CAA D125 8932 BE24 C5CA
The key is available from keys.gnupg.net by searching for [security@grafana](http://keys.gnupg.net/pks/lookup?search=security@grafana&fingerprint=on&op=index.
Security announcements
We maintain a category on the community site named Security Announcements,
where we will post a summary, remediation, and mitigation details for any patch containing security fixes. You can also subscribe to email updates to this category if you have a grafana.com account and sign in to the community site, or via updates from our Security Announcements RSS feed.
Acknowledgement
We would like to thank Tran Viet Tuan for responsibly disclosing the initially discovered vulnerability to us.
References