ET ATTACK_RESPONSE Possible PowerShell AMSI Bypass Inbound

Query · suricata

flow:from_server,established;
http.stat_code;
content:"200";
http.response_body;
content:".Assembly.GetType"; fast_pattern; nocase;
content:"|7c 25 7b 5b|char|5d 5b|"; distance:0; within:80;
content:"-replace"; nocase;
content:"GetField|28|"; nocase;
content:"SetValue|28|"; nocase;
Raw source ET ATTACK_RESPONSE Possible PowerShell AMSI Bypass Inbound · Suricata
Esc
Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert http any any -> [$HOME_NET,$HTTP_SERVERS] any (
    msg:"ET ATTACK_RESPONSE Possible PowerShell AMSI Bypass Inbound";
    flow:from_server,established;
    http.stat_code;
    content:"200";
    http.response_body;
    content:".Assembly.GetType"; fast_pattern; nocase;
    content:"|7c 25 7b 5b|char|5d 5b|"; distance:0; within:80;
    content:"-replace"; nocase;
    content:"GetField|28|"; nocase;
    content:"SetValue|28|"; nocase;
    classtype:misc-attack;
    sid:2039683; rev:1;
    metadata:attack_target Client_and_Server, created_at 2022_11_04, deployment Perimeter, deployment Internal, confidence Medium, signature_severity Minor, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_11_04;
)

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