The US State Department has released its 2010 International Narcotics Control Strategy Report. While the DPRK seems to do a fair trade in bootleg cigarettes in Rason and currency counterfeiting:
No confirmed instances of large-scale drug trafficking involving the DPRK state or its nationals were reported in 2009. This is the seventh consecutive year that there were no known instances of large-scale methamphetamine or heroin trafficking to either Japan or Taiwan with direct DPRK state institution involvement. From the mid- 1990s through to 2002/2003, numerous instances of narcotics trafficking involving DPRK persons and important state assets, such as sea-going vessels and military patrol boats, were recorded in Taiwan and Japan.
[…]
The source of relatively small quantities of methamphetamine seized elsewhere in Asia can occasionally be traced back to the China-DPRK border area. Local press reports in Asia describe apprehensions of traffickers smuggling methamphetamine and indicate that arrangements to purchase that methamphetamine were made in towns near the China-DPRK border. These reports suggest that trafficking of methamphetamine continues along the China-DPRK border and they raise the question of whether or not local DPRK officials might be aware or even complicit in the drug trade. There is no clear evidence of a central role for DPRK state institutions in selling methamphetamine or organizing the trafficking of methamphetamine. Evidence of direct DPRK state involvement in drug trafficking to Taiwan and Japan emerged regularly in the past.
Reports of non-narcotics related acts of criminality in the DPRK suggest that DPRK tolerance of criminal behavior may exist on a larger, organized scale, even if no large-scale narcotics trafficking incidents involving the state itself have come to light.
Yonhap’s Hwang Doo-hyang has a good summary on the report’s assessment of both Koreas. You can read or download the PDF of the report at the State Department’s website. The DPRK profile begins on page 488.