PHPCSUtils: Remote code execution via eval() in AbstractArrayDeclarationSniff::getActualArrayKey()

### Impact PHPCSUtils versions 1.0.0-alpha1 through 1.2.2 contain an arbitrary code execution vulnerability in `PHPCSUtils\AbstractSniffs\AbstractArrayDeclarationSniff::getActualArrayKey()`. The vulnerable method is reached by any sniff that extends `AbstractArrayDeclarationSniff` and calls `getActualArrayKey()`. Running PHPCS over untrusted PHP code through such a sniff, for example, in a CI pipeline that lints pull requests, or on a developer machine reviewing third-party code, could lead to arbitrary command execution on the scanning host. The vulnerability happens when the method determines the value of an array key using `eval()`. A maliciously crafted array key such as `'system'('id')` would be executed when the code was scanned. ### Known attack vectors Known code paths that reach the vulnerable method include the following PHPCSExtra sniffs: - `Universal.Arrays.DuplicateArrayKey` - `Universal.Arrays.MixedArrayKeyTypes` Other packages that call `AbstractArrayDeclarationSniff::getActualArrayKey()` may also be vulnerable. ### Patches This issue has been fixed in PHPCSUtils 1.2.3. We recommend all users upgrade to 1.2.3 or later. ### Workaround Users who cannot upgrade immediately can disable the sniffs that reach the vulnerable method by adding `<exclude>` tags to their custom ruleset (replace the placeholder standard and sniff names with the ones used in your setup): ```xml <rule ref="Standard"> <exclude name="Standard.Category.SniffName"/> </rule> ``` For example, to disable the two PHPCSExtra sniffs listed under "Known attack vectors": ```xml <rule ref="Universal"> <exclude name="Universal.Arrays.DuplicateArrayKey"/> <exclude name="Universal.Arrays.MixedArrayKeyTypes"/> </rule> ``` To verify that the sniffs have been disabled, run PHPCS with the `-e` flag, which lists all the sniffs a standard will run. The excluded sniffs should no longer appear in the output: ``` phpcs -e --standard=/path/to/ruleset.xml ``` ### Credits Many thanks to [@rodrigoprimo](https://github.com/rodrigoprimo) for responsibly disclosing this vulnerability. ### How can I report a security bug? Please report security vulnerabilities privately via [the "Security and quality" tab on the PHPCSUtils repository](https://github.com/PHPCSStandards/PHPCSUtils/security).