When we first set out to identify malicious extensionsour expectation was to find banking trojans and pass-word stealers that duplicated the strategies pioneered byZeus and SpyEye. In practice, the abusive extensionecosystem is drastically different from malicious bina-ries. Monetization hinges on direct or indirect relation-ships with syndicated search partners and ad injection af-filiate programs, some of which earn millions of dollarsfrom infected users [37]. Miscreants derive wealth fromtrafficanduser targetingrather than the computing re-sources or privileged access mediated via the browser. Itmay simply be that the authors of malicious binaries havelittle incentive (or external pressure) to change, leavingextensions to a distinct set of actors. This uncertainty isa strong motivation for exploring the extension ecosys-tem further.