rule win_grimagent_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        version = "1"
        description = "Detects win.grimagent."
        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.grimagent"
        malpedia_rule_date = "20260422"
        malpedia_hash = "a182e35da64e6d71cb55f125c4d4225196523f14"
        malpedia_version = "20260504"
        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 = { 83c001 8945f8 8b4d0c 51 e8???????? }
            // n = 5, score = 100
            //   83c001               | add                 eax, 1
            //   8945f8               | mov                 dword ptr [ebp - 8], eax
            //   8b4d0c               | mov                 ecx, dword ptr [ebp + 0xc]
            //   51                   | push                ecx
            //   e8????????           |                     

        $sequence_1 = { 894d0c ebd0 8b5508 0fb602 8b4d0c }
            // n = 5, score = 100
            //   894d0c               | mov                 dword ptr [ebp + 0xc], ecx
            //   ebd0                 | jmp                 0xffffffd2
            //   8b5508               | mov                 edx, dword ptr [ebp + 8]
            //   0fb602               | movzx               eax, byte ptr [edx]
            //   8b4d0c               | mov                 ecx, dword ptr [ebp + 0xc]

        $sequence_2 = { 83c101 894d0c ebd0 8b5508 0fb602 }
            // n = 5, score = 100
            //   83c101               | add                 ecx, 1
            //   894d0c               | mov                 dword ptr [ebp + 0xc], ecx
            //   ebd0                 | jmp                 0xffffffd2
            //   8b5508               | mov                 edx, dword ptr [ebp + 8]
            //   0fb602               | movzx               eax, byte ptr [edx]

        $sequence_3 = { 750e c745e801000000 b801000000 eb1a 8b4df0 }
            // n = 5, score = 100
            //   750e                 | jne                 0x10
            //   c745e801000000       | mov                 dword ptr [ebp - 0x18], 1
            //   b801000000           | mov                 eax, 1
            //   eb1a                 | jmp                 0x1c
            //   8b4df0               | mov                 ecx, dword ptr [ebp - 0x10]

        $sequence_4 = { 8b4dfc 51 e8???????? 85c0 7434 8d95d0feffff 52 }
            // n = 7, score = 100
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   51                   | push                ecx
            //   e8????????           |                     
            //   85c0                 | test                eax, eax
            //   7434                 | je                  0x36
            //   8d95d0feffff         | lea                 edx, [ebp - 0x130]
            //   52                   | push                edx

        $sequence_5 = { 3bc2 7514 8b45ec 83c002 8945ec 8b4dfc 83c102 }
            // n = 7, score = 100
            //   3bc2                 | cmp                 eax, edx
            //   7514                 | jne                 0x16
            //   8b45ec               | mov                 eax, dword ptr [ebp - 0x14]
            //   83c002               | add                 eax, 2
            //   8945ec               | mov                 dword ptr [ebp - 0x14], eax
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   83c102               | add                 ecx, 2

        $sequence_6 = { ebbe 8b550c 8955fc 8b450c 50 }
            // n = 5, score = 100
            //   ebbe                 | jmp                 0xffffffc0
            //   8b550c               | mov                 edx, dword ptr [ebp + 0xc]
            //   8955fc               | mov                 dword ptr [ebp - 4], edx
            //   8b450c               | mov                 eax, dword ptr [ebp + 0xc]
            //   50                   | push                eax

        $sequence_7 = { 7426 8b5508 0fbe02 8b4d0c 0fbe11 3bc2 }
            // n = 6, score = 100
            //   7426                 | je                  0x28
            //   8b5508               | mov                 edx, dword ptr [ebp + 8]
            //   0fbe02               | movsx               eax, byte ptr [edx]
            //   8b4d0c               | mov                 ecx, dword ptr [ebp + 0xc]
            //   0fbe11               | movsx               edx, byte ptr [ecx]
            //   3bc2                 | cmp                 eax, edx

        $sequence_8 = { 83c101 894d0c ebd0 8b5508 0fb602 8b4d0c 0fb611 }
            // n = 7, score = 100
            //   83c101               | add                 ecx, 1
            //   894d0c               | mov                 dword ptr [ebp + 0xc], ecx
            //   ebd0                 | jmp                 0xffffffd2
            //   8b5508               | mov                 edx, dword ptr [ebp + 8]
            //   0fb602               | movzx               eax, byte ptr [edx]
            //   8b4d0c               | mov                 ecx, dword ptr [ebp + 0xc]
            //   0fb611               | movzx               edx, byte ptr [ecx]

        $sequence_9 = { 8bec 8b4508 0fbe08 85c9 7426 8b5508 }
            // n = 6, score = 100
            //   8bec                 | mov                 ebp, esp
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]
            //   0fbe08               | movsx               ecx, byte ptr [eax]
            //   85c9                 | test                ecx, ecx
            //   7426                 | je                  0x28
            //   8b5508               | mov                 edx, dword ptr [ebp + 8]

    condition:
        7 of them and filesize < 582656
}