JavaScript makes e-mail bugging easy

Love those 'features'

A simple bit of invisible JavaScript code can enable the sender of an e-mail memo to intercept all recipients' comments when the memo is forwarded, the Privacy Foundation has announced in an advisory.

The exploit enables monitoring the forwarded path of an e-mail message and written comments attached.

"In a business negotiation conducted via email, one side can learn inside information from the other side as the proposal is discussed through the recipient company's internal email system," the advisory notes.

It's also a handy way for spammers to harvest thousands of fresh, live addresses.

Victims of the bugging technique will have HTML and JavaScript enabled in their e-mail clients. It's a good hack, as it doesn't exploit a flaw, but rather a standard feature of current, 'state of the art' e-mail bloatware.

"Affected e-mail readers include Outlook, Outlook Express, and Netscape 6 Mail. Earlier versions of Netscape are not affected because they do not support all the features of the JavaScript Document Object Model (DOM). Also Eudora and the AOL 6.0 email readers are not affected because JavaScript is turned off by default. Hotmail and other Web-based email systems automatically remove JavaScript programs from incoming email messages and therefore are not vulnerable," the advisory says.

We can't think of a single good reason to enable JavaScript in an e-mail client, or any penalty for disabling it. However, if a sensible person with JavaScript disabled forwards a bugged message to someone who has it enabled, the second recipient's forwarded messages can be tracked.

Instructions for disabling JavaScript in each of the affected clients are included in the Privacy Foundation advisory. We recommend that readers waste no time in following them. ®

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