APT_Webshell_SUPERNOVA_2

rule APT_Webshell_SUPERNOVA_2
{
    meta:
        author = "FireEye"
        description = "This rule is looking for specific strings related to SUPERNOVA. SUPERNOVA is a .NET web shell backdoor masquerading as a legitimate SolarWinds web service handler. SUPERNOVA inspects and responds to HTTP requests with the appropriate HTTP query strings, Cookies, and/or HTML form values (e.g. named codes, class, method, and args)."
        reference = "https://www.fireeye.com/blog/threat-research/2020/12/evasive-attacker-leverages-solarwinds-supply-chain-compromises-with-sunburst-backdoor.html"
        date = "2020-12-14"
        score = 85
        id = "c39bf9ba-fd62-5619-92b6-1633375ef197"
    strings:
        $dynamic = "DynamicRun"
        $solar = "Solarwinds" nocase
        $string1 = "codes"
        $string2 = "clazz"
        $string3 = "method"
        $string4 = "args"
    condition:
        uint16(0) == 0x5a4d and uint32(uint32(0x3C)) == 0x00004550 and filesize < 10KB and 3 of ($string*) and $dynamic and $solar
}