10:00 ET, 12 November 2013

Security experts at Securi firm have recently detected a series of SQL Injection attacks conducted abusing of the Google Bot activity.

The exploitation of search engines like Google and Bing to conduct an attack represents an optimal choice for hackers that intend to stay hidden during the offensive. No IT administrator would block traffic from the popular search engines, but it must be considered that a legitimate search engine bot could also be abused to attack a targeted site.

bot

It’s not a paranoid hypotesys on a possible attack scenario, it is exactly what happened a few days ago to a website of a client of Securi security firm. Securi experts began blocking Google’s IP addresses because of the requests originated from them were crafted to perform a SQLi attacks.

The situation appeared paradoxical, Google was conducting a SQL Injection attack against a website, following the logs that demonstrates what happened. To protect the victim’s identity the log has been modified.

66.249.66.138 – – [05/Nov/2013:00:28:40 -0500] “GET /url.php?variable=”)%20declare%20@q%20varchar(8000(%20select%20@q%20=%200×527%20exec(@q)%20– HTTP/1.1″ 403 4439 “-” “Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)”

The analysis of origin IPs revealed that the source if the attack was the legitimate Google bot, following the report on one of them:

$ host 66.249.66.138

138.66.249.66.in-addr.arpa domain name pointer crawl-66-249-66-138.googlebot.com.

NetRange:       66.249.64.0 – 66.249.95.255

CIDR:           66.249.64.0/19

OriginAS:

NetName:        GOOGLE

Which is the attacks schema?
It’s well known the use of Google bot to crawl the Internet and to index the content of the visited websites, every single link embedded in the website is inspected by the crawler independently of its forms and target.

In this scenario, the bot was crawling Site A. Site A had a number of links embedded that had the SQLi requests to the target site, Site B. Google Bot then following links and executes the malicious requests against the Site B starting to inadvertently attack it.

Under these assumptions an hacker could create malicious links on a vulnerable website waiting that Google Bot crawler will inspect them to run malicious strings against another website. The principal advantage of the technique is to conduct an attack totally in a stealthy way, Google Bot will be apparently the unique responsible!

“John goes to his site, Site A, he adds all this awesome content about kittens and cupcakes, but in the process he adds a number of what appear to be benign links that are unsuspecting to the user reading, but very effective to the bot crawling the site. Those links are riddled with RFI and SQLi attacks that allow John to plead ignorance, also allowing him to stay two arms lengths away from Site B. This doesn’t mean he can’t verify success, it just means he doesn’t open himself to early detection by more active scanning and attacks.” the post states.

The security experts at Securi have already advised Google about the possible abuse of its Bot activity, site admin are advised, before to trust any source it is necessary a further level of inspection.

Pierluigi Paganini

(Security Affairs – Google Bot, hacking)

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