This paper presents Solar, a system for automatic synthesis of adversarial contracts that exploit vulnerabilities in a victim smart contract. To make the synthesis tractable, we introduce a query language as well as \emph{summary-based symbolic evaluation}, which significantly reduces the number of instructions that our synthesizer needs to evaluate symbolically, without compromising the precision of the vulnerability query. We encoded common vulnerabilities of smart contracts and evaluated \toolname on the entire data set from \etherscan. Our experiments demonstrate the benefits of summary-based symbolic evaluation and show that \toolname outperforms state-of-the-art smart contracts analyzers, \teether, \mythril, and \contractfuzz, in terms of running time, precision, and soundness.