YARA Rule for BlackCat Threat Hunting

rule win_blackcat_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-03-28"
        version = "1"
        description = "Detects win.blackcat."
        info = "autogenerated rule brought to you by yara-signator"
        tool = "yara-signator v0.6.0"
        signator_config = "callsandjumps;datarefs;binvalue"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.blackcat"
        malpedia_rule_date = "20230328"
        malpedia_hash = "9d2d75cef573c1c2d861f5197df8f563b05a305d"
        malpedia_version = "20230407"
        malpedia_license = "CC BY-SA 4.0"
        malpedia_sharing = "TLP:WHITE"

    /* DISCLAIMER
     * The strings used in this rule have been automatically selected from the
     * disassembly of memory dumps and unpacked files, using YARA-Signator.
     * The code and documentation is published here:
     * https://github.com/fxb-cocacoding/yara-signator
     * As Malpedia is used as data source, please note that for a given
     * number of families, only single samples are documented.
     * This likely impacts the degree of generalization these rules will offer.
     * Take the described generation method also into consideration when you
     * apply the rules in your use cases and assign them confidence levels.
     */


    strings:
        $sequence_0 = { c3 81f90a010000 7e6a 81f9e2030000 0f8fcc000000 81f90b010000 }
            // n = 6, score = 600
            //   c3                   | ret                 
            //   81f90a010000         | cmp                 ecx, 0x10a
            //   7e6a                 | jle                 0x6c
            //   81f9e2030000         | cmp                 ecx, 0x3e2
            //   0f8fcc000000         | jg                  0xd2
            //   81f90b010000         | cmp                 ecx, 0x10b

        $sequence_1 = { 85f6 0f8482000000 bb03000000 8d0437 }
            // n = 4, score = 600
            //   85f6                 | test                esi, esi
            //   0f8482000000         | je                  0x88
            //   bb03000000           | mov                 ebx, 3
            //   8d0437               | lea                 eax, [edi + esi]

        $sequence_2 = { 885405cc 48 eb19 89ca 83fa63 7fbe }
            // n = 6, score = 600
            //   885405cc             | mov                 byte ptr [ebp + eax - 0x34], dl
            //   48                   | dec                 eax
            //   eb19                 | jmp                 0x1b
            //   89ca                 | mov                 edx, ecx
            //   83fa63               | cmp                 edx, 0x63
            //   7fbe                 | jg                  0xffffffc0

        $sequence_3 = { f20f104808 8d45d4 894dec c645f004 8d4dec }
            // n = 5, score = 600
            //   f20f104808           | movsd               xmm1, qword ptr [eax + 8]
            //   8d45d4               | lea                 eax, [ebp - 0x2c]
            //   894dec               | mov                 dword ptr [ebp - 0x14], ecx
            //   c645f004             | mov                 byte ptr [ebp - 0x10], 4
            //   8d4dec               | lea                 ecx, [ebp - 0x14]

        $sequence_4 = { 3d32210000 747b 3d33210000 0f8571050000 8b07 }
            // n = 5, score = 600
            //   3d32210000           | cmp                 eax, 0x2132
            //   747b                 | je                  0x7d
            //   3d33210000           | cmp                 eax, 0x2133
            //   0f8571050000         | jne                 0x577
            //   8b07                 | mov                 eax, dword ptr [edi]

        $sequence_5 = { b005 5e 5d c3 81f90a010000 7e6a 81f9e2030000 }
            // n = 7, score = 600
            //   b005                 | mov                 al, 5
            //   5e                   | pop                 esi
            //   5d                   | pop                 ebp
            //   c3                   | ret                 
            //   81f90a010000         | cmp                 ecx, 0x10a
            //   7e6a                 | jle                 0x6c
            //   81f9e2030000         | cmp                 ecx, 0x3e2

        $sequence_6 = { 747b 3d33210000 0f8571050000 8b07 83f00a }
            // n = 5, score = 600
            //   747b                 | je                  0x7d
            //   3d33210000           | cmp                 eax, 0x2133
            //   0f8571050000         | jne                 0x577
            //   8b07                 | mov                 eax, dword ptr [edi]
            //   83f00a               | xor                 eax, 0xa

        $sequence_7 = { b806000000 c7460400000000 894608 c70601000000 83c430 }
            // n = 5, score = 600
            //   b806000000           | mov                 eax, 6
            //   c7460400000000       | mov                 dword ptr [esi + 4], 0
            //   894608               | mov                 dword ptr [esi + 8], eax
            //   c70601000000         | mov                 dword ptr [esi], 1
            //   83c430               | add                 esp, 0x30

        $sequence_8 = { 89d0 ba3e000000 897e0c f7e2 }
            // n = 4, score = 600
            //   89d0                 | mov                 eax, edx
            //   ba3e000000           | mov                 edx, 0x3e
            //   897e0c               | mov                 dword ptr [esi + 0xc], edi
            //   f7e2                 | mul                 edx

        $sequence_9 = { c6410b00 66c741090000 8b45ec 894110 c7411400000000 b801000000 8901 }
            // n = 7, score = 600
            //   c6410b00             | mov                 byte ptr [ecx + 0xb], 0
            //   66c741090000         | mov                 word ptr [ecx + 9], 0
            //   8b45ec               | mov                 eax, dword ptr [ebp - 0x14]
            //   894110               | mov                 dword ptr [ecx + 0x10], eax
            //   c7411400000000       | mov                 dword ptr [ecx + 0x14], 0
            //   b801000000           | mov                 eax, 1
            //   8901                 | mov                 dword ptr [ecx], eax

    condition:
        7 of them and filesize < 29981696
}