The U.K. website of Amnesty International, a human rights watchdog organization, was compromised by hackers, who used it to infect visitors with a remote access Trojan horse program known as Gh0st RAT, security firm Websense reported on Friday.
Websense's automated malware scanners detected the compromise on the Amnesty site on Tuesday and Wednesday, Websense security researcher Gianluca Giuliani, said in a blog post on Friday. The attackers managed to inject malicious code that attempted to exploit a Java vulnerability known as CVE-2012-0507 into the site's homepage, he said.
The same vulnerability was exploited earlier this year to infect more than 600,000 Mac computers with the Flashback malware. It was patched in Java for Windows back in February and in Java for Mac in April.
The exploit code used in this attack appears to have been copied from Metasploit, an open source penetration testing framework popular among security professionals, Giuliani said.
The exploit was designed to install a version of Gh0st RAT, a computer Trojan horse that is usually associated with targeted attacks. However, the company believes that this compromise was the result of larger Web attack campaign.
Websense detected over 100 other websites infected with the same malicious code as Amnesty International's U.K. website during the same time period, Carl Leonard, senior manager of Websense Security Labs, said.
The Websense researchers also noticed similarities between this compromise and a different one detected last week on the website of the Israeli Institute for National Security Studies.
Hackers are starting to use advanced persistent threats (APTs) like Gh0st RAT in mass attacks because they are very efficient, Leonard said. Gh0st RAT gives attackers complete control over infected systems and allows them to copy the victims' documents, emails, passwords and other sensitive information, Giuliani said in the blog post.
The Gh0st RAT executable installed on victims' machines as a result of this attack had a low antivirus detection rate and was signed with a valid digital certificate issued by VeriSign to a Chinese company. Security researchers have pointed out in the past that digitally signed malicious files have a higher chance of not being detected by security products.
The digital certificate used in this case was most likely stolen, Leonard said. Websense has notified VeriSign about the abuse, but doesn't know if the certificate has been revoked yet, he said.
Amnesty International's U.K. website has been compromised and was used to serve malware several times before -- most recently in December 2011. The organization's Hong Kong website has also been infected in a similar manner in the past.
Amnesty's U.K. website appears to have been cleaned as of Friday, but the Gh0st RAT variant used in this attack still has a low antivirus detection rate, Leonard said.
In order to protect themselves from such Web-based exploitation attacks, also known as drive-by downloads, users should keep their computer software up to date, especially the browser plug-ins. Website owners should also make sure that the software used on their websites, including its plug-ins, is current, and should harden their Web server environments in order to prevent infection, Leonard said.