I believe OP meant that binary packages may not correspond to the sources they were supposed to be built from, and it's hard to check whether they actually do.
Posted Dec 8, 2012 21:22 UTC (Sat) by oever (subscriber, #987)
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Yes, I meant that it is hard to match binary to source. Publishing a binary with spyware and claiming that it corresponds to source code which has no spyware can go undetected.
In the above example of WordPress, I assume OP checked the production PHP code. Since WordPress is shipped only as source (as far as I know), this would rule out the presence of spyware in the site.
If the site was running a compiled CGI plugin, finding that the source code has no spyware, does not mean that the binary has no spyware. The spyware might even be in the apache binary.