codeql/change-notes/1.18/analysis-javascript.md

Improvements to JavaScript analysis

General improvements

• Additional heuristics have been added to semmle.javascript.heuristics. Add import semmle.javascript.heuristics.all to a query in order to activate all of the heuristics at once.

• Modelling of data flow through destructuring assignments has been improved. This may give additional results for the security queries and other queries that rely on data flow.

• Support for popular libraries has been improved. Consequently, queries may produce more results on code bases that use the following libraries:

  • bluebird
  • browserid-crypto
  • cookie-parser
  • cookie-session
  • crypto-js
  • express-jwt
  • express-session
  • fast-json-parse
  • forge
  • json-parse-better-errors
  • json-parse-safe
  • json-safe-parse
  • MySQL2
  • parse-json
  • q
  • safe-json-parse

New queries

Query	Tags	Purpose
Disabling Electron webSecurity (js/disabling-electron-websecurity)	security, frameworks/electron	Highlights Electron browser objects that are created with the webSecurity property set to false. Results shown on LGTM by default.
Enabling Electron allowRunningInsecureContent (js/enabling-electron-insecure-content)	security, frameworks/electron	Highlights Electron browser objects that are created with the allowRunningInsecureContent property set to true. Results shown on LGTM by default.
Use of externally-controlled format string (js/tainted-format-string)	security, external/cwe/cwe-134	Highlights format strings containing user-provided data, indicating a violation of CWE-134. Results shown on LGTM by default.

Changes to existing queries

Query	Expected impact	Change
Arguments redefined	Fewer results	This rule previously also flagged redefinitions of eval. This was an oversight that is now fixed.
CORS misconfiguration for credentials transfer	More true-positive results	This rule now treats header names case-insensitively.
Hard-coded credentials	More true-positive results	This rule now recognizes secret cryptographic keys.
Incomplete sanitization	More true-positive results	This rule now recognizes incomplete URL encoding and decoding.
Insecure randomness	More true-positive results	This rule now recognizes secret cryptographic keys.
Missing rate limiting	More true-positive results, fewer false-positive results	This rule now recognizes additional rate limiters and expensive route handlers.
Missing X-Frame-Options HTTP header	Fewer false-positive results	This rule now treats header names case-insensitively.
Reflected cross-site scripting	Fewer false-positive results	This rule now treats header names case-insensitively.
Server-side URL redirect	More true-positive results	This rule now treats header names case-insensitively.
Superfluous trailing arguments	Fewer false-positive results	This rule now ignores calls to some empty functions.
Uncontrolled command line	More true-positive results	This rule now recognizes indirect command injection through sh -c and similar.
Unused variable	Fewer results	This rule no longer flags class expressions that could be made anonymous. While technically true, these results are not interesting.
Unused variable	Renamed	This rule has been renamed to "Unused variable, import, function or class" to reflect the fact that it flags different kinds of unused program elements.

Changes to QL libraries

• HTTP header names are now always normalized to lower case to reflect the fact that they are case insensitive. In particular, the result of HeaderDefinition.getAHeaderName, and the first parameter of HeaderDefinition.defines, ExplicitHeaderDefinition.definesExplicitly and RouteHandler.getAResponseHeader is now always a lower-case string.
• The class JsonParseCall has been deprecated. Use JsonParserCall instead.
• The handling of spread arguments in the data flow library has been changed: DataFlow::InvokeNode.getArgument(i) is now only defined when there is no spread argument at or before argument position i, and similarly InvokeNode.getNumArgument is only defined for invocations without spread arguments.