The BBC reports that Black Hat presenters Bruce Potter and Sasha Woods described at this year's Black Hat Briefings a security flaw in Linux servers
: too few events are feeding the entropy pool
from which random numbers are drawn, which leaves the systems "more susceptible to well-known attacks." Unfortunately, [Potter] said, the entropy of the data streams on Linux servers was often very low because the machines were not generating enough raw information for them.
Also, he said, server security software did little to check whether a data stream had high or low entropy.
These pools often ran dry leaving encryption systems struggling to get good seeds for their random number generators, said Mr Potter. This might meant they were easier to guess and more susceptible to a brute force attack because seeds for new numbers were generated far less regularly than was recommended. Update: 08/10 01:05 GMT
: Please note that Sasha Woods' name was mis-reported as Sasha Moore; that's now been changed in the text above.