JavaScript spy creates an e-mail wiretap
- — 06 February, 2001 10:42
"It really is a wiretap and it's very illegal and very easy to do," said Richard Smith, chief technology officer for the Privacy Foundation based in Denver, in a column he wrote for the non-profit educational and research organisation. The vulnerability exists in mail that uses HTML (HyperText Markup Language).
A few lines of JavaScript can be embedded in an e-mail message and allows the recipient's mail to be returned to the original sender. It only works, however, if the recipient's e-mail program is set to read JavaScript.
Smith learned about the e-mail exploit while working on research on Web bugs, an invisible image embedded in a Web page or e-mail that quietly transmits a message back to a remote computer when viewed. He corresponded with Carl Voth, an engineer in British Columbia, who told him about the JavaScript vulnerability. Voth is believed to have discovered the flaw he calls the "reaper exploit" in October 1998.
Computer scientists from the Privacy Foundation have learned that the exploit only works when the recipient is using an HTML/JavaScript-enabled e-mail reader such as Microsoft Outlook, Outlook Express or version 6 of Netscape Communications' Web browser package. Eudora, Qualcomm's e-mail software, and version 6 of America Online's latest client software are not affected as JavaScript is turned off by default. Microsoft's Hotmail and other Web-based e-mail systems automatically remove JavaScript programs from incoming email messages and therefore are not vulnerable.
The Microsoft Security Response Centre investigated the exploit when it was first discovered more than two years ago and looked into it again two weeks ago when contacted by Smith, a company spokeswoman said.
"This is not a product flaw -- this is inherently in the nature of HTML mail," the spokeswoman said. "Customers who do not want this functionality can disable it. It's disabled by default on recent versions of our e-mail clients."
The Outlook Security Patch, which has been available for almost a year, configures Outlook in a way that prevents scripts from running in HTML e-mails. The most recent version of Outlook Express disables the scripting in HTML e-mails by default, the spokeswoman said.
Smith, in his column, worries that the exploit may be used often and people may try to gain access to information that they normally would not be privileged to see. For example, a user may send a resume via email and then learn what the potential employer thinks about his or her qualifications, Smith writes.
The Privacy Foundation has requested Microsoft and Netscape to turn off JavaScript code by default in all of their email readers. Little use is seen for JavaScript in email, only pitfalls such as viruses, email spam and now the wiretapping problem, Smith said.
Smith's column and further information on the exploit can be viewed at http://www.privacyfoundation.org/.
