Metabase is an open-source business intelligence and analytics platform. Prior to versions 0.43.7.3, 0.44.7.3, 0.45.4.3, 0.46.6.4, 1.43.7.3, 1.44.7.3, 1.45.4.3, and 1.46.6.4, a vulnerability could potentially allow remote code execution on ones Metabase server. The core issue is that one of the supported data warehouses (an embedded in-memory database H2), exposes a number of ways for a connection string to include code that is then executed by the process running the embedded database. Because Metabase allows users to connect to databases, this means that a user supplied string can be used to inject executable code. Metabase allows users to validate their connection string before adding a database (including on setup), and this validation API was the primary vector used as it can be called without validation. Versions 0.43.7.3, 0.44.7.3, 0.45.4.3, 0.46.6.4, 1.43.7.3, 1.44.7.3, 1.45.4.3, and 1.46.6.4 fix this issue by removing the ability of users to add H2 databases entirely. As a workaround, it is possible to block these vulnerabilities at the network level by blocking the endpoints POST /api/database, PUT /api/database/:id, and POST /api/setup/validateuntil. Those who use H2 as a file-based database should migrate to SQLite.
Weakness
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
Affected Software
| Name |
Vendor |
Start Version |
End Version |
| Metabase |
Metabase |
* |
0.43.7.3 (excluding) |
| Metabase |
Metabase |
* |
1.43.7.3 (excluding) |
| Metabase |
Metabase |
0.44.0 (including) |
0.44.7.3 (excluding) |
| Metabase |
Metabase |
0.45.0 (including) |
0.45.4.3 (excluding) |
| Metabase |
Metabase |
0.46.0 (including) |
0.46.6.4 (excluding) |
| Metabase |
Metabase |
1.44.0 (including) |
1.44.7.3 (excluding) |
| Metabase |
Metabase |
1.45.0 (including) |
1.45.4.3 (excluding) |
| Metabase |
Metabase |
1.46.0 (including) |
1.46.6.4 (excluding) |
Potential Mitigations
- Run your code in a “jail” or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product.
- Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection.
- This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise.
- Be careful to avoid CWE-243 and other weaknesses related to jails.
- Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- To reduce the likelihood of code injection, use stringent allowlists that limit which constructs are allowed. If you are dynamically constructing code that invokes a function, then verifying that the input is alphanumeric might be insufficient. An attacker might still be able to reference a dangerous function that you did not intend to allow, such as system(), exec(), or exit().
- For Python programs, it is frequently encouraged to use the ast.literal_eval() function instead of eval, since it is intentionally designed to avoid executing code. However, an adversary could still cause excessive memory or stack consumption via deeply nested structures [REF-1372], so the python documentation discourages use of ast.literal_eval() on untrusted data [REF-1373].
References