APT_Backdoor_SUNBURST_1

YARA detection rule by FireEye · NOASSERTION

This rule is looking for portions of the SUNBURST backdoor that are vital to how it functions. The first signature fnv_xor matches a magic byte xor that the sample performs on process, service, and driver names/paths. SUNBURST is a backdoor that has the ability to spawn and kill processes, write and delete files, set and create registry keys, gather system information, and disable a set of forensic analysis tools and services.

rule APT_Backdoor_SUNBURST_1
{
    meta:
        author = "FireEye"
        description = "This rule is looking for portions of the SUNBURST backdoor that are vital to how it functions. The first signature fnv_xor matches a magic byte xor that the sample performs on process, service, and driver names/paths. SUNBURST is a backdoor that has the ability to spawn and kill processes, write and delete files, set and create registry keys, gather system information, and disable a set of forensic analysis tools and services."
        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 = "74b44844-5575-53d7-819b-ab1b2327a144"
    strings:
        $cmd_regex_encoded = "U4qpjjbQtUzUTdONrTY2q42pVapRgooABYxQuIZmtUoA" wide
        $cmd_regex_plain = { 5C 7B 5B 30 2D 39 61 2D 66 2D 5D 7B 33 36 7D 5C 7D 22 7C 22 5B 30 2D 39 61 2D 66 5D 7B 33 32 7D 22 7C 22 5B 30 2D 39 61 2D 66 5D 7B 31 36 7D }
        $fake_orion_event_encoded = "U3ItS80rCaksSFWyUvIvyszPU9IBAA==" wide
        $fake_orion_event_plain = { 22 45 76 65 6E 74 54 79 70 65 22 3A 22 4F 72 69 6F 6E 22 2C }
        $fake_orion_eventmanager_encoded = "U3ItS80r8UvMTVWyUgKzfRPzEtNTi5R0AA==" wide
        $fake_orion_eventmanager_plain = { 22 45 76 65 6E 74 4E 61 6D 65 22 3A 22 45 76 65 6E 74 4D 61 6E 61 67 65 72 22 2C }
        $fake_orion_message_encoded = "U/JNLS5OTE9VslKqNqhVAgA=" wide
        $fake_orion_message_plain = { 22 4D 65 73 73 61 67 65 22 3A 22 7B 30 7D 22 }
        $fnv_xor = { 67 19 D8 A7 3B 90 AC 5B }
    condition:
        $fnv_xor and ($cmd_regex_encoded or $cmd_regex_plain) or ( ($fake_orion_event_encoded or $fake_orion_event_plain) and ($fake_orion_eventmanager_encoded or $fake_orion_eventmanager_plain) and ($fake_orion_message_encoded and $fake_orion_message_plain) )
}

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

8bc11205-5ff3-4e22-a574-ff0d0b0d8563

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

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