THINK twice before uploading
your holiday pictures to Facebook
- you could be helping someone
to steal information from your
computer. A botnet called
Stegobot was created to show
how easy it would be for a crook
to hijack Facebook photos to
create a secret communication
channel that is very difficult to
detect.
Like most botnets, Stegobot gains
control of computers by tricking
users into opening infected email
attachments or visiting suspect
websites. But rather than
contacting the botmasters
directly, it piggybacks on the
infected user's normal social
network activity. "If one of your
friends is a friend of a friend of
the botmaster, the information
transfers hop by hop within the
social network, finally reaching
the botmasters," says Amir
Houmansadr, a computer scientist
at the University of Illinois at
Urbana-Champaign who worked
on the botnet.
Stegobot takes advantage of a
technique called steganography
to hide information in picture files
without changing their
appearance. It is possible to store
around 50 kilobytes of data in a
720 by 720 pixel image - enough
to transmit any passwords or
credit card numbers that
Stegobot might find on your hard
drive.
The botnet inserts this
information into any photo you
upload to Facebook, and then
waits for one of your friends to
look at your profile. They don't
even have to click on the photo,
as Facebook helpfully downloads
files in the background. If your
friend is also infected with the
botnet - quite likely, since any
email you send them will pass it
on - any photo they upload will
also pass on the stolen data.
From there, the data will
eventually make its way to the
account of someone who is also
friends with the botmaster,
allowing them to extract details
on your identity. The botmasters
can also send commands to the
botnet through the reverse
process - uploading a photo with
hidden instructions that make
their way to infected computers.
"It's scary because it's virtually
undetectable," says Shishir
Nagaraja of the Indraprastha
Institute of Information
Technology, New Delhi, India,
who led the project.
Marco Cova , a computer scientist
at the University of Birmingham,
UK, says that criminals could
employ a system like Stegobot, as
it is hard to detect, but other
methods allow them to steal
much larger quantities of data.
"It's not the most efficient or
convenient way," he says.
your holiday pictures to Facebook
- you could be helping someone
to steal information from your
computer. A botnet called
Stegobot was created to show
how easy it would be for a crook
to hijack Facebook photos to
create a secret communication
channel that is very difficult to
detect.
Like most botnets, Stegobot gains
control of computers by tricking
users into opening infected email
attachments or visiting suspect
websites. But rather than
contacting the botmasters
directly, it piggybacks on the
infected user's normal social
network activity. "If one of your
friends is a friend of a friend of
the botmaster, the information
transfers hop by hop within the
social network, finally reaching
the botmasters," says Amir
Houmansadr, a computer scientist
at the University of Illinois at
Urbana-Champaign who worked
on the botnet.
Stegobot takes advantage of a
technique called steganography
to hide information in picture files
without changing their
appearance. It is possible to store
around 50 kilobytes of data in a
720 by 720 pixel image - enough
to transmit any passwords or
credit card numbers that
Stegobot might find on your hard
drive.
The botnet inserts this
information into any photo you
upload to Facebook, and then
waits for one of your friends to
look at your profile. They don't
even have to click on the photo,
as Facebook helpfully downloads
files in the background. If your
friend is also infected with the
botnet - quite likely, since any
email you send them will pass it
on - any photo they upload will
also pass on the stolen data.
From there, the data will
eventually make its way to the
account of someone who is also
friends with the botmaster,
allowing them to extract details
on your identity. The botmasters
can also send commands to the
botnet through the reverse
process - uploading a photo with
hidden instructions that make
their way to infected computers.
"It's scary because it's virtually
undetectable," says Shishir
Nagaraja of the Indraprastha
Institute of Information
Technology, New Delhi, India,
who led the project.
Marco Cova , a computer scientist
at the University of Birmingham,
UK, says that criminals could
employ a system like Stegobot, as
it is hard to detect, but other
methods allow them to steal
much larger quantities of data.
"It's not the most efficient or
convenient way," he says.
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