Miscreants attacked one of the Websites belonging to the U.S. Postal Service using the Blackhole Exploit kit to deliver up to nine Trojans customized for the user's system.
Cyber-attackers hacked one of the sites belonging to the
U.S. Postal Service to redirect visitors to an attack portal containing Trojans.
The USPS national customer support center, ribbs.usps.gov,
was compromised using the Blackhole Exploit Kit, researchers at Zscaler
said April 7. Attackers injected
users to a different site.
The USPS has taken down the infected site and it appears the
page the attackers redirect visitors to is offline as well. As of early April 8,
Google still reported the site as "may harm your computer" on its search
results page and Firefox flagged it as a "Reported Attack Page."
obfuscated as each letter was encoded using its ASCII equivalent. To any user,
it looks like a series of numbers enclosed within a <script> tag. Zscaler
decoded the code to find it was a redirect to load a Russian domain within an
When the malicious code was executed, by the user clicking
on a link, for example, users were redirected to the Russian site that had been
automatically send the visitors to another site with a Cook Islands domain.
The users never saw the intermediary page, which may have
been another legitimate site that had been compromised, Zscaler researchers
Instead, they saw the final attack portal, which displayed a
404 Page Not Found error message. In actuality, a drive-by-download was running
executed, checked the victim's operating system, browser type, and the state of
important software components such as ActiveX and Java. A payload customized to
the user's system information and existing unpatched vulnerabilities was
There were nine Trojans to choose from, including executable
files, malicious PDF files and PHP scripts. The PHP files exploited known Java
vulnerabilities. According to Virus Total, none of them would have been
detected by most major antivirus programs. Three of the potential downloads -
an executable and two malicious PDF files - were the best recognized, with five
out of 42 antivirus programs tracked by Virus Total able to detect them.
The Blackhole Exploit kit, a commercial kit developed by
Russian developers, has been used in a number of attacks, according to Zscaler.
used allows individuals with little or no coding knowledge to deliver a
hostile payload, whether that is scareware software or something else. A recent
Symantec report found that automated attack kits targeting Websites accounted
for two-thirds of all Web-based attacks in 2010.
The same Blackhole Exploit was behind the malicious
advertisements that appeared on the free version of Spotify
The name of the affected site, http://ribbs.usps.gov
stands for Rapid Information Bulletin Board System. The site handles the postal
service's Intelligent Mail services, such as barcode-based tracking for business mail.