Research in information security, risk management and investment has grown in importance over the last few years. However, without reliable estimates on attack probabilities, risk management is difficult to do in practice. Using a novel data set, we provide estimates on attack propensity and how it changes with disclosure and patching of vulnerabilities. Disclosure of software vulnerability has been controversial. On one hand are those who propose full and instant disclosure whether the patch is available or not and on the other hand are those who argue for limited or no disclosure. Which of the two policies is socially optimal depends critically on how attack frequency changes with disclosure and patching. In this paper, we empirically explore the impact of vulnerability information disclosure and availability of patches on attacks targeting the vulnerability. Our results suggest that on an average both secret (non-published) and published (published and not patched) vulnerabilities attract fewer attacks than patched (published and patched) vulnerabilities. When we control for time since publication and patches, we find that patching an already known vulnerability decreases the number of attacks, although attacks gradually increase with time after patch release. Patching an unknown vulnerability, however, causes a spike in attacks, which then gradually decline after patch release. Attacks on secret vulnerabilities slowly increase with time until the vulnerability is published and then attacks rapidly decrease with time after publication.