This attack could pose a serious security threat. You should take immediate action to stop any damage or prevent further damage from happening.
This signature detects attempts to download exploits and payloads from Angler exploit kit that may compromise a computer through various vendor vulnerabilities.
Angler is an exploit kit that allows the remote attacker to perform various malicious actions on the compromised computer. Angler Exploit Kit commonly checks to see if the PC is having some AV software and has IE, Java or Flash vulnerable. If Angler Exploit Kit finds some AV software installed on computer it avoids dropping the exploit and payload.
This exploit kit is known for dropping cryptolocker, Powliks, bedep etc payload, if attack is successful.