codeql/change-notes/1.20/analysis-javascript.md

Improvements to JavaScript analysis

General improvements

• Support for many frameworks and libraries has been improved, in particular for:

  • a-sync-waterfall
  • Electron
  • Express
  • hapi
  • js-cookie
  • React
  • socket.io
  • Vue

• File classification now recognizes additional generated files, for example, files from HTML Tidy.

• The taint tracking library now recognizes flow through persistent storage, class fields, and callbacks in certain cases. Handling of regular expressions has also been improved. This may give more results for the security queries.

• Type inference for function calls has been improved. This may give additional results for queries that rely on type inference.

• The Closure-Library module system is now supported.

New queries

Query	Tags	Purpose
Arbitrary file write during archive extraction ("Zip Slip") (js/zipslip)	security, external/cwe/cwe-022	Identifies extraction routines that allow arbitrary file overwrite vulnerabilities, indicating a possible violation of CWE-022. Results are shown on LGTM by default.
Arrow method on Vue instance (js/vue/arrow-method-on-vue-instance)	reliability, frameworks/vue	Highlights arrow functions that are used as methods on Vue instances. Results are shown on LGTM by default.
Cross-window communication with unrestricted target origin (js/cross-window-information-leak)	security, external/cwe/201, external/cwe/359	Highlights code that sends potentially sensitive information to another window without restricting the receiver window's origin, indicating a possible violation of CWE-201. Results are shown on LGTM by default.
Double escaping or unescaping (js/double-escaping)	correctness, security, external/cwe/cwe-116	Highlights potential double escaping or unescaping of special characters, indicating a possible violation of CWE-116. Results are shown on LGTM by default.
Incomplete regular expression for hostnames (js/incomplete-hostname-regexp)	correctness, security, external/cwe/cwe-020	Highlights hostname sanitizers that are likely to be incomplete, indicating a violation of CWE-020. Results are shown on LGTM by default.
Incomplete URL substring sanitization	correctness, security, external/cwe/cwe-020	Highlights URL sanitizers that are likely to be incomplete, indicating a violation of CWE-020. Results shown on LGTM by default.
Incorrect suffix check (js/incorrect-suffix-check)	correctness, security, external/cwe/cwe-020	Highlights error-prone suffix checks based on indexOf, indicating a potential violation of CWE-20. Results are shown on LGTM by default.
Loop iteration skipped due to shifting (js/loop-iteration-skipped-due-to-shifting)	correctness	Highlights code that removes an element from an array while iterating over it, causing the loop to skip over some elements. Results are shown on LGTM by default.
Unused property (js/unused-property)	maintainability	Highlights properties that are unused. Results are shown on LGTM by default.
Useless comparison test (js/useless-comparison-test)	correctness	Highlights code that is unreachable due to a numeric comparison that is always true or always false. Results are shown on LGTM by default.

Changes to existing queries

Query	Expected impact	Change
Ambiguous HTML id attribute	Fewer false positive results	This query now treats templates more conservatively. Its precision has been revised to 'high'.
Assignment to exports variable	Fewer results	This query no longer flags code that is also flagged by the query "Useless assignment to local variable".
Client-side cross-site scripting	More true positive and fewer false positive results.	This query now recognizes WinJS functions that are vulnerable to HTML injection. It no longer flags certain safe uses of jQuery, and recognizes custom sanitizers.
Hard-coded credentials	Fewer false positive results	This query no longer flags the empty string as a hardcoded username.
Insecure randomness	More results	This query now flags insecure uses of crypto.pseudoRandomBytes.
Reflected cross-site scripting	Fewer false positive results.	This query now recognizes custom sanitizers.
Stored cross-site scripting	Fewer false positive results.	This query now recognizes custom sanitizers.
Unbound event handler receiver (js/unbound-event-handler-receiver)	Fewer false positive results	Additional ways that class methods can be bound are now recognized.
Uncontrolled data used in network request	More results	This query now recognizes host values that are vulnerable to injection.
Uncontrolled data used in path expression	Fewer false positive results	This query now recognizes the Express root option, which prevents path traversal.
Unneeded defensive code	More true positive and fewer false positive results	This query now recognizes additional defensive code patterns.
Unsafe dynamic method access	Fewer false positive results	This query no longer flags concatenated strings as unsafe method names.
Unused parameter	Fewer false positive results	This query no longer flags parameters with leading underscore.
Unused variable, import, function or class	Fewer false positive results	This query now flags fewer variables that are implicitly used by JSX elements. It no longer flags variables with a leading underscore and variables in dead code.
Unvalidated dynamic method call	More true positive results	This query now flags concatenated strings as unvalidated method names in more cases.
Useless assignment to property.	Fewer false positive results	This query now treats assignments with complex right-hand sides correctly.
Useless conditional	Fewer results	Additional defensive coding patterns are now ignored.
Useless conditional	More true positive results	This query now flags additional uses of function call values.

Changes to QL libraries

• DataFlow::SourceNode is no longer an abstract class; to add new source nodes, extend DataFlow::SourceNode::Range instead.
• Subclasses of DataFlow::PropRead are no longer automatically made source nodes; you now need to additionally define a corresponding subclass of DataFlow::SourceNode::Range to achieve this.
• The deprecated libraries semmle.javascript.DataFlow and semmle.javascript.dataflow.CallGraph have been removed; they are both superseded by semmle.javascript.dataflow.DataFlow.
• Overriding DataFlow::InvokeNode.getACallee() no longer affects the call graph seen by the interprocedural data flow libraries. To do this, the 1-argument version getACallee(int imprecision) can be overridden instead.
• The predicate DataFlow::returnedPropWrite was intended for internal use only and is no longer available.