The researchers said the bug, which they trace back to a Black Hat presentation in 2013, was fixed by AWS on Oct. 1, with public disclosure coming on Wednesday.
The proposed regulation makes exceptions for exchanges of technology for the purposes of vulnerability disclosure, cyber incident response or basic software patching.
Researchers performed a large-scale analysis of a data set of malicious samples that crashed in the Zscaler Cloud Sandbox, studying coding errors to determine if there are ways to leverage vulnerabilities to prevent malware from loading in the first place.
Morphisec researchers noted that the new delivery chain uses the Nitro Pro PDF application, commencing with the distribution of a more than 100 MB MSI installer payload, which uses the Advanced Installer app for obfuscation and enables threat actors to evade anti-malware engines.