"Redacted" DoJ PDFs still leaking confidential data

[David Farber <dave () farber net>]

Begin forwarded message:

> From: Matt Blaze <mab () crypto com>
> Date: May 17, 2008 6:45:11 PM EDT
> To: David Farber <dave () farber net>
> Subject: "Redacted" DoJ PDFs still leaking confidential data

> Dave,
>
> For IP if you'd like.
>
> As someone whose research involves wiretapping and
> surveillance technology, I read with some interest a
> recent DoJ Inspector General's audit report on the FBI's
> CALEA implementation efforts.  I was particularly
> interested in some of the numbers, which seem to contradict
> the FBI's claims that some wiretapping vulnerabilities my
> grad students and I discovered a couple of years ago
> had been largely fixed.
>
> But I was particularly surprised when I tried to cut and
> paste some of the text from the (redacted) PDF report into
> an email message to one of my students, and some redacted
> data appeared in the message.  Sure enough, the "sensitive"
> data in some of the report's tables was redacted simply by
> covering it with an opaque PDF layer, widely known to be an
> insecure -- and completely ineffective -- technique for
> obfuscating sensitive information.  The opaque layer is
> easily removed by Acrobat or simply by cutting and pasting.
>
> Data leaks from ineffectively redacted PDFs go back for
> years, and the DoJ itself has been burned by this several
> times already; one would think the government might have
> learned by now.  In this case, the "sensitive" data is
> fairly innocuous (and, I'd argue, was data the public has a
> legitimate right to know in any case). But if this represents
> the DoJ's normal redaction practices, next time it could just
> as easily be a court filing containing the names of
> confidential informants.
>
> Last night, after I blogged about it, the DoJ took the entire
> web site for its Office of the Inspector General off the air,
> presumably to check for other leaky PDFs.
>
> For the original leaky PDF and context, see my
> blog post at
>     http://www.crypto.com/blog/calea_retrobugs/
>
> -matt

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