Waledac has reawakened more than a year after Microsoft shut down the botnet. However, the new incarnation has far more dangerous capabilities as it steals passwords.
spam botnet has reawakened
and its new password-stealing capabilities make it a much more dangerous threat
than the older one Microsoft shut down more than a year ago, according to Palo
infected with the new variant of Waledac still send out spam, but the malware
has added capabilities to steal passwords and authentication information from
compromised systems, said Wade Williamson, a senior security analyst at Palo
Alto Networks. Palo Alto Networks first detected
the new variant
on Feb. 2 in customer networks, Williamson said. It
publicized its findings on Feb. 15.
Waledac malware sniffs user credentials for FTP, POP3 and SMTP accounts as well
as stealing configuration files for FTP and BitCoin, the virtual currency often
used for online transactions. The core behavior, communications methods,
internal operations and delivery mechanism remain the same, said Williamson.
The source code is essentially the same, Palo Alto Networks has determined.
back, but the gang behind it is "being much more quiet and trying to stay
under the radar this time," said Williamson.
down the Waledac botnet
by seizing the malicious domains associated with
the botnet and law-enforcement authorities seized command-and-control (C&C)
servers in 2010. Since then, Waledac "wasn't there at all,"
takedown, Waledac was a "decent-sized" spam botnet that accounted for
about 1 percent of the global spam volume. Unlike its newer variant, the
original Waledac was devoted to spewing out spam as fast as it could to as many
targets as possible. While it was not pleasant for enterprises to have a spam
bot operating on their networks, the impact was generally limited to just
higher bandwidth bills and network congestion, said Williamson.
Waledac is easily "more dangerous" because it is capable of sifting
out log-in credentials and sensitive information and transmitting it to
external adversaries to use in other attacks. Recent events have shown that
serious breaches and compromises could be traced back to having the password on
an email account stolen, said Williamson.
attackers relied on log-in credentials stolen from seven senior executives to
break into Nortel Networks in 2000, according to a Feb. 14 report in The Wall Street Journal
decade-long security breach.
noted that even though the source code is essentially the same, the current
threat is a variant of the original botnet and uses new domains and command-and-control
servers. The new Waledac also uses proxies and exhibits other dynamic behavior
when looking for the C&C server to connect to, said Williamson.
Networks is still analyzing the variant, and it was still too soon to speculate
whether the group behind the original Waledac has resumed operations, or if a
brand-new group had somehow acquired the code, said Williamson. It is clear,
however, that criminals are reusing infrastructure and techniques that have
been proven to work.
sighting comes a few days after Kaspersky Lab researchers discovered a new
variant of the Kelihos
botnet. The new samples are based on original
Kelihos code but use different encryption keys, said Maria Garnaeva, a
Kaspersky researcher. Like its predecessor, the latest Kelihos is also sending
out large volumes of spam.
that we are dealing with another botnet," said Alex Gostev, chief security
expert of Kaspersky Lab.
was taken offline
last September after Microsoft seized the domains used by
the C&C infrastructure. Microsoft was aided in its efforts by Kaspersky
Lab. As part of the takedown, Microsoft introduced a new server into the botnet
infrastructure and pushed out the IP address to all the infected machines to connect
to this server instead of other malicious ones.
appears [a] new botnet infrastructure may be being built with the new variant
of Kelihos malware," Richard Boscovich, senior attorney in Microsoft's
digital crimes unit, wrote Feb. 3 on Microsoft's
Microsoft still has control over the original Kelihos botnet. The C&C
servers that had controlled Kelihos are not sending any commands to infected
machines, and no spam is being sent by the machines infected with the earlier
version of the malware, according to Gostev.
The fact that
both botnets reappeared around the same time is interesting, as security
experts believe Waledac
source code was used in developing Kelihos.
difficult to tell at this point whether the perpetrators are resuming
operations, having learned some lessons from the takedown, or if the code has
been sold to newcomers, said Williamson.