Impact
The proxy mode of WireMock, can be protected by the network restrictions configuration, as documented in Preventing proxying to and recording from specific target addresses. These restrictions can be configured using the domain names, and in such a case the configuration is vulnerable to the DNS rebinding attacks. A similar patch was applied in WireMock 3.0.0-beta-15 for the WireMock Webhook Extensions.
The root cause of the attack is a defect in the logic which allows for a race condition triggered by a DNS server whose address expires in between the initial validation and the outbound network request that might go to a domain that was supposed to be prohibited. Control over a DNS service is required to exploit this attack, so it has high execution complexity and limited impact.
Affected versions
- WireMock 3,x until 3.0.3 (security patch), on default settings in environments with access to the network
- WireMock 2.x until 2.35.1 (security patch), on default settings in environments with access to the network
- Python WireMock until 2.6.1
- WireMock Studio - all versions, this proprietary product was discontinued in 2022
Patches
- WireMock 3.0.3 + the 3.0.3-1 Docker image
- WireMock 2.35.1 + the 2.35.1-1 Docker image - backport to WireMock 2.x
- Python WireMock 2.6.1
Workarounds
For WireMock:
- Option 1: Configure WireMock to use IP addresses instead of the domain names in the outbound URLs subject to DNS rebinding
- Option 2: Use external firewall rules to define the list of permitted destinations
For WireMock Studio: N/A. Switch to another distribution, there will be no fix provided. The vendor of former WireMock Studio recommends migration to WireMock Cloud
References
- CVE-2023-41327 - Related issue in the WireMock Webhooks Extension
NVD description
WireMock is a tool for mocking HTTP services. The proxy mode of WireMock, can be protected by the network restrictions configuration, as documented in Preventing proxying to and recording from specific target addresses. These restrictions can be configured using the domain names, and in such a case the configuration is vulnerable to the DNS rebinding attacks. A similar patch was applied in WireMock 3.0.0-beta-15 for the WireMock Webhook Extensions. The root cause of the attack is a defect in the logic which allows for a race condition triggered by a DNS server whose address expires in between the initial validation and the outbound network request that might go to a domain that was supposed to be prohibited. Control over a DNS service is required to exploit this attack, so it has high execution complexity and limited impact. This issue has been addressed in version 2.35.1 of wiremock-jre8 and wiremock-jre8-standalone, version 3.0.3 of wiremock and wiremock-standalone, version 2.6.1 of the python version of wiremock, and versions 2.35.1-1 and 3.0.3-1 of the wiremock/wiremock Docker container. Users are advised to upgrade. Users unable to upgrade should either configure firewall rules to define the list of permitted destinations or to configure WireMock to use IP addresses instead of the domain names.