Most of the computer security white papers in the Reading Room have been written by students seeking GIAC certification to fulfill part of their certification requirements and are provided by SANS as a resource to benefit the security community at large. SANS attempts to ensure the accuracy of information, but papers are published "as is". Errors or inconsistencies may exist or may be introduced over time as material becomes dated. If you suspect a serious error, please contact firstname.lastname@example.org.
A recent report on botnet threats (Dhamballa, 2010) provides a sobering read for any security professional. According to its authors, the number of computers that fell victim to botnets grew at the rate of 8%/week in 2010, which translates to more than a six-fold increase over the course of the year.
A covert data channel is a communications channel that is hidden within the medium of a legitimate communications channel. Covert channels manipulate a communications medium in an unexpected or unconventional way in order to transmit information in an almost undetectable fashion. Otherwise said, a covert data channel transfers arbitrary bytes between two points in a fashion that would appear legitimate to someone scrutinizing the exchange. (Bingham, 2006)
Steganography is the practice of concealing information in channels that superficially appear benign. The National Institute of Standards and Technology defines a covert channel as any communication channel that can be exploited
Although the current threat of steganographic technology appears to lag its usefulness, the diligent information systems person needs to be mindful of the security ramifications that a covert channel in their enterprise carries.