Further analysis of the latest version of Stuxnet indicates the Duqu worm may be attacking certificate authorities in order to obtain legitimate keys to masquerade as a trusted application.
As Symantec continues its analysis of Duqu,
the latest malware targeting industrial control firms and based on the
Stuxnet worm, other security researchers believe that certificate
authorities are among the affected victims.
Symantec posted its preliminary analysis of the Duqu worm
on Oct. 18. Duqu's focus appears to be on industrial control systems,
but unlike Stuxnet, its goal appears to be information gathering and
not disabling hardware. However, a pair of researchers from McAfee
noted that the team behind Duqu may have compromised certificate
authorities along the way.
Based on their own analysis, McAfee's Venere and Szor claimed Duqu had
been used in "professional, targeted attacks" against various
certificate authorities in southern Europe, Middle East, parts of Asia
"It is highly likely that this key, just like the previous two
known cases, was not really stolen from the actual companies, but
instead directly generated in the name of such companies at a CA as
part of a direct attack," wrote Venere and Szor, noting that Stuxnet
had used two digital certificates belonging to companies in Taiwan, as
McAfee Labs advised Certificate Authorities to "carefully
verify" their systems to ensure they weren't compromised by Duqu or
other "variations." The digital certificate used by Duqu belonged to a
Taiwanese company, C-Media Electronics, according to McAfee. It was
most likely not stolen, but was legitimately issued by a compromised
The certificate in question was revoked on Oct. 14 by VeriSign, the
certificate authority recently acquired by Symantec. However, based on
its internal investigation, Symantec said the private key used for the
certificates had been stolen from its customers. VeriSign had not been
tricked into issuing certificates to attackers. The company used
"correct processes" to authenticate and verify the certificate was
being requested by a legitimate customer, according to Symantec.
"At no time were Symantec's roots and intermediate CAs at risk,
nor were there any issues with any CA, intermediate, or other VeriSign
or Thawte brands of certificates," Symantec said.
The rogue SSL certificate was used to authenticate itself and sign
Duqu's driver files, according to Symantec's analysis. This allowed
Duqu to act as a trusted application within the network and communicate
with other systems and applications because its components had been
signed by a "legitimate" certificate, Jeff Hudson, CEO of Venafi, told
Organizations must maintain a complete inventory of all certificates
issued by certificate authorities, monitor them, and know which ones
are within policy. That way, administrators will know which ones aren't
compliant and revoke them, Hudson said.
IT departments should be investing in a "solid logging
infrastructure" to notice connections to unknown, foreign hosts, Bill
Roth, CMO of LogLogic, told eWEEK. "People who do not monitor their
networks with a log management infrastructure are like the homeowner
who buys fake surveillance cameras for their house...and still gets
ripped off," Roth said.
It's not just logging, as organizations should have a "mix of
tools" to detect and block suspicious activity, Jason Lewis, CTO of
Lookingglass, told eWEEK. The mix can include a Web proxy to control
what sites employees are accessing, a firewall and intrusion prevention
system can block malicious traffic, and two-factor authentication is
better at securing accounts and services than just passwords, said
"Using all of these elements together increases the likelihood of catching malicious activity quickly," Lewis said.