Eudora users warned over ‘reply to all’ trick

Press Send for a buffer flow flaw

By John Leyden • Get more from this author

Posted in Security, 11th November 2003 15:20 GMT

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A buffer overflow vulnerability in Eudora, the popular email client, creates a mechanism for crackers to compromise targeted PCs.

The problem stems from a failure to properly verify the "From:" and "Reply-To:" when users of vulnerable versions of Eudora select "Reply-To-All". This shortcoming creates a means for hackers to spam users with a maliciously constructed email designed to trigger this buffer overflow condition.

In practice it might be hard to trick users into selecting "Reply-To-All" in response to suspicious emails. But if they do then crackers would be able to run arbitrary code on vulnerable systems, so the problem is not to be sniffed at.

The vulnerability was discovered in Eudora version 5.x by Japanese security researcher Hisayuki Shinmachi of Secure Net Services in January and announced yesterday. Users are advised to update to Eudora 5.1-Jr3 (Japanese) or Eudora 6.0 (English) in order to shore up their security defences, as explained in an advisory by Secunia here.

Although Eudora security problems are not unprecedented, the package is far less afflicted with security issues than Microsoft's email client, known in these parts as Lookout. ®