rule win_grok_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.grok."
        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.grok"
        malpedia_rule_date = "20260916"
        malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6"
        malpedia_version = "20260917"
        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 = { 8b450c 56 57 8b7d08 03c7 8945fc }
            // n = 6, score = 400
            //   8b450c               | mov                 eax, dword ptr [ebp + 0xc]
            //   56                   | push                esi
            //   57                   | push                edi
            //   8b7d08               | mov                 edi, dword ptr [ebp + 8]
            //   03c7                 | add                 eax, edi
            //   8945fc               | mov                 dword ptr [ebp - 4], eax

        $sequence_1 = { 393a 740a 41 83c240 3bce 72f4 }
            // n = 6, score = 400
            //   393a                 | cmp                 dword ptr [edx], edi
            //   740a                 | je                  0xc
            //   41                   | inc                 ecx
            //   83c240               | add                 edx, 0x40
            //   3bce                 | cmp                 ecx, esi
            //   72f4                 | jb                  0xfffffff6

        $sequence_2 = { 059c010000 3930 741a ff30 56 e8???????? a1???????? }
            // n = 7, score = 400
            //   059c010000           | add                 eax, 0x19c
            //   3930                 | cmp                 dword ptr [eax], esi
            //   741a                 | je                  0x1c
            //   ff30                 | push                dword ptr [eax]
            //   56                   | push                esi
            //   e8????????           |                     
            //   a1????????           |                     

        $sequence_3 = { 394dfc 7507 b8250200c0 eb1b 8b55ec 8b4508 03420c }
            // n = 7, score = 400
            //   394dfc               | cmp                 dword ptr [ebp - 4], ecx
            //   7507                 | jne                 9
            //   b8250200c0           | mov                 eax, 0xc0000225
            //   eb1b                 | jmp                 0x1d
            //   8b55ec               | mov                 edx, dword ptr [ebp - 0x14]
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]
            //   03420c               | add                 eax, dword ptr [edx + 0xc]

        $sequence_4 = { 3bc1 75f2 32db 6a00 ffb2c4010000 ff15???????? 8ac3 }
            // n = 7, score = 400
            //   3bc1                 | cmp                 eax, ecx
            //   75f2                 | jne                 0xfffffff4
            //   32db                 | xor                 bl, bl
            //   6a00                 | push                0
            //   ffb2c4010000         | push                dword ptr [edx + 0x1c4]
            //   ff15????????         |                     
            //   8ac3                 | mov                 al, bl

        $sequence_5 = { 51 8b5514 52 6a01 8d85e0feffff 50 68???????? }
            // n = 7, score = 400
            //   51                   | push                ecx
            //   8b5514               | mov                 edx, dword ptr [ebp + 0x14]
            //   52                   | push                edx
            //   6a01                 | push                1
            //   8d85e0feffff         | lea                 eax, [ebp - 0x120]
            //   50                   | push                eax
            //   68????????           |                     

        $sequence_6 = { 7408 8b00 3bc1 75f2 32db 6a00 ffb2c4010000 }
            // n = 7, score = 400
            //   7408                 | je                  0xa
            //   8b00                 | mov                 eax, dword ptr [eax]
            //   3bc1                 | cmp                 eax, ecx
            //   75f2                 | jne                 0xfffffff4
            //   32db                 | xor                 bl, bl
            //   6a00                 | push                0
            //   ffb2c4010000         | push                dword ptr [edx + 0x1c4]

        $sequence_7 = { 8975d8 668975dc 668975de 8975e0 668975e4 668975e6 8975e8 }
            // n = 7, score = 400
            //   8975d8               | mov                 dword ptr [ebp - 0x28], esi
            //   668975dc             | mov                 word ptr [ebp - 0x24], si
            //   668975de             | mov                 word ptr [ebp - 0x22], si
            //   8975e0               | mov                 dword ptr [ebp - 0x20], esi
            //   668975e4             | mov                 word ptr [ebp - 0x1c], si
            //   668975e6             | mov                 word ptr [ebp - 0x1a], si
            //   8975e8               | mov                 dword ptr [ebp - 0x18], esi

        $sequence_8 = { 51 51 834dfcff 53 8d45f8 50 }
            // n = 6, score = 400
            //   51                   | push                ecx
            //   51                   | push                ecx
            //   834dfcff             | or                  dword ptr [ebp - 4], 0xffffffff
            //   53                   | push                ebx
            //   8d45f8               | lea                 eax, [ebp - 8]
            //   50                   | push                eax

        $sequence_9 = { 721a ff30 e8???????? eb1d 83fe08 720c ff7004 }
            // n = 7, score = 400
            //   721a                 | jb                  0x1c
            //   ff30                 | push                dword ptr [eax]
            //   e8????????           |                     
            //   eb1d                 | jmp                 0x1f
            //   83fe08               | cmp                 esi, 8
            //   720c                 | jb                  0xe
            //   ff7004               | push                dword ptr [eax + 4]

    condition:
        7 of them and filesize < 84992
}

rule win_grok_w0 {
	meta:
	    author = "Kaspersky Lab"
	    copyright = "Kaspersky Lab"
	    description = "Rule to detect the crypto library used in Equation group malware"
	    version = "1.0"
	    last_modified = "2015-02-16"
	    reference = "https://securelist.com/blog/"
	    source = "https://github.com/mattulm/sfiles_yara/blob/master/malware/Equation.yar"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.grok"
        malpedia_version = "20170517"
        malpedia_sharing = "TLP:WHITE"
        malpedia_license = ""
	strings:
	    $a={37 DF E8 B6 C7 9C 0B AE 91 EF F0 3B 90 C6 80 85 5D 19 4B 45 44 12 3C E2 0D 5C 1C 7B C4 FF D6 05 17 14 4F 03 74 1E 41 DA 8F 7D DE 7E 99 F1 35 AC B8 46 93 CE 23 82 07 EB 2B D4 72 71 40 F3 B0 F7 78 D7 4C D1 55 1A 39 83 18 FA E1 9A 56 B1 96 AB A6 30 C5 5F BE 0C 50 C1}
	condition:
	    $a
}