SANS ISC: Strange wordpress login patterns

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SANS ISC InfoSec Forums

Reader Robert came today with a very interesting situation. He noticed odd wordpress login patterns:

T 31.47.254.62:51020 -> X.X.X.X:80 [AP]
POST /wp-login.php HTTP/1.1.
User-Agent: Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html).
Host: **redacted**
Accept: */*.
Cookie: wordpress_test_cookie=WP+Cookie+check.
Content-Length: 131.
Content-Type: application/x-www-form-urlencoded.
.
log=admin&pwd=admin%21%21%21&wp-submit=Log+In&redirect_to=http://**redacted**/wp-admin/tes1a0&testcookie=1

----------------------------------

T 62.210.207.146:43322 -> X.X.X.X:80 [AP]
POST /wp-login.php HTTP/1.1.
User-Agent: Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html).
Host: **redacted**
Accept: */*.
Cookie: wordpress_test_cookie=WP+Cookie+check.
Content-Length: 113.
Content-Type: application/x-www-form-urlencoded.
.
log=ahenry&pwd=Ahenry%24%24%24&wp-submit=Log+In&redirect_to=http://**redacted**/wp-admin/tes1a0&testcookie=1

----------------------------------

T 109.199.82.5:46902 -> X.X.X.X:80 [AP]
POST /wp-login.php HTTP/1.1.
User-Agent: Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html).
Host: **redacted**
Accept: */*.
Cookie: wordpress_test_cookie=WP+Cookie+check.
Content-Length: 110.
Content-Type: application/x-www-form-urlencoded.
.
log=natemc&pwd=Johns666&wp-submit=Log+In&redirect_to=http://**redacted**/wp-admin/tes1a0&testcookie=1

In the sample he sent to us, there are three specific source IP address: 109.199.82.5, 62.210.207.146 and 31.47.254.62. All three IP address have good reputation (checked on TrustedSource, SenderBase and SANS Internet Storm Center). Looks like the client is trying to reach a script called tes1a0 and setting the WordPress test cookie so Wordpress can tell the client is accepting cookies and no error is rised. I checked for the string tes1a0 in the Wordpress 4.1 installation download and it's not part of the code. It's also clear this is a fake google bot. Please check the previous diary by Dr. Johannes Ullrich on how to check when google is not google.

Have you seen this kind of wordpress attempts? If yes, let us know via Contact form. I will update the diary with the information gathered.

Manuel Humberto Santander Peláez
SANS Internet Storm Center - Handler
Twitter:@manuelsantander
Web:http://manuel.santander.name
e-mail: msantand at isc dot sans dot org