> For the complete documentation index, see [llms.txt](https://davidjosearaujo.gitbook.io/online-courses/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://davidjosearaujo.gitbook.io/online-courses/blockchain-security/blockchain-in-action/attacking-blockchain-nodes/malicious-transactions.md).

# Malicious transactions

Blockchain is software that is designed to process untrusted user input (i.e., transactions)

Injection attacks take advantage of flaws in input validation or processing to exploit the machine using them. Blockchain software can be vulnerable to injection as well

The impact of the malicious input can vary greatly. Some attacks enable VM breakouts, allowing a malicious actor to attack the underlying system