Update WP Super Cache and W3TC Immediately ? Remote Code Execution Vulnerability

[djbaxter]

Update WP Super Cache and W3TC Immediately ? Remote Code Execution Vulnerability Disclosed
by Tony Perez, Sucuri.net
April 23, 2013

Shame on us for not catching this a month ago when it was first reported, but it seems that two of the biggest caching plugins in WordPress have what we would classify a very serious vulnerability ? remote code execution (RCE), a.k.a., arbitrary code execution....

A really simple way to test is leave yourself a comment like this:

<!?mfunc echo PHP_VERSION; ?><!?/mfunc?>

​

If it works, it?ll show you something like this:

You can see that it?s showing the version of my server?s PHP install. No big deal right? Wrong. This means I can pass any commands I want to your server and they?ll execute, hence the term remote command execution (RCE).

In this instance all I said was echo, or print out, the version of my PHP, in it of itself is benign. Replace my echo with an eval and encode a payload and now it?s a different ball game. Case in point, a backdoor shell, all while going via your comments and bypassing all other authentication controls.

Again, not an issue to be taken lightly, this is a very serious vulnerability, further exasperated by the fact that any user can exploit it. The easiest way to protect yourself is to upgrade. You can find the latest updates on the WordPress.org repository:

• WP Super Cache
• W3TC Total Cache

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