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VOLEXITY_Informational_Win_3Cx_Msi

YARA detection rule by threatintel@volexity.com · See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt

Detects 3CX installers created in March 2023, 3CX was known to be compromised at this time.

rule VOLEXITY_Informational_Win_3Cx_Msi: UTA0040 {
  meta:
    description     = "Detects 3CX installers created in March 2023, 3CX was known to be compromised at this time."
    author          = "threatintel@volexity.com"
    id              = "ac26e7b1-61eb-5074-bcda-46d714bdba4c"
    date            = "2023-03-30"
    modified        = "2023-03-30"
    reference       = "https://www.reddit.com/r/crowdstrike/comments/125r3uu/20230329_situational_awareness_crowdstrike/"
    source_url      = "https://github.com/volexity/threat-intel/blob/62e031ea574efde68dac7d38dc23438466a5302b/2023/2023-03-30 3CX/indicators/rules.yar#L134-L152"
    license_url     = "https://github.com/volexity/threat-intel/blob/62e031ea574efde68dac7d38dc23438466a5302b/LICENSE.txt"
    logic_hash      = "c04de2653ef587f27c7ebf058c6f6c345e16b67f36ccc4306bc49f8c4394728e"
    score           = 75
    quality         = 80
    tags            = "UTA0040"
    hash1           = "aa124a4b4df12b34e74ee7f6c683b2ebec4ce9a8edcf9be345823b4fdcf5d868"
    memory_suitable = 0
    license         = "See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt"

  strings:
    $cert = { 1B 66 11 DF 9C 9A 4D 6E CC 8E D5 0C 9B 91 78 73 }
    $app  = "3CXDesktopApp.exe"
    $data = "202303"

  condition:
    all of them
}

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

41b126a9-b3d3-468e-94b8-45416c2578b7

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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

[[ reason ]]

What does this mean?

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.

[[ reason ]]

What do these messages mean?

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

[[ currentRule.title ]]

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