rule win_metastealer_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        version = "1"
        description = "Detects win.metastealer."
        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.metastealer"
        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 = { ff74c120 ff7514 e8???????? 83c410 eb32 50 53 }
            // n = 7, score = 300
            //   ff74c120             | push                dword ptr [ecx + eax*8 + 0x20]
            //   ff7514               | push                dword ptr [ebp + 0x14]
            //   e8????????           |                     
            //   83c410               | add                 esp, 0x10
            //   eb32                 | jmp                 0x34
            //   50                   | push                eax
            //   53                   | push                ebx

        $sequence_1 = { ff710c 68???????? 50 e8???????? 8b16 83c424 8b4208 }
            // n = 7, score = 300
            //   ff710c               | push                dword ptr [ecx + 0xc]
            //   68????????           |                     
            //   50                   | push                eax
            //   e8????????           |                     
            //   8b16                 | mov                 edx, dword ptr [esi]
            //   83c424               | add                 esp, 0x24
            //   8b4208               | mov                 eax, dword ptr [edx + 8]

        $sequence_2 = { f7d9 51 50 e8???????? 83c408 c640ff2d 48 }
            // n = 7, score = 300
            //   f7d9                 | neg                 ecx
            //   51                   | push                ecx
            //   50                   | push                eax
            //   e8????????           |                     
            //   83c408               | add                 esp, 8
            //   c640ff2d             | mov                 byte ptr [eax - 1], 0x2d
            //   48                   | dec                 eax

        $sequence_3 = { e8???????? 8bc8 0fb6d1 c1f908 898d88f6ffff 85d2 0f84b0000000 }
            // n = 7, score = 300
            //   e8????????           |                     
            //   8bc8                 | mov                 ecx, eax
            //   0fb6d1               | movzx               edx, cl
            //   c1f908               | sar                 ecx, 8
            //   898d88f6ffff         | mov                 dword ptr [ebp - 0x978], ecx
            //   85d2                 | test                edx, edx
            //   0f84b0000000         | je                  0xb6

        $sequence_4 = { e8???????? 837e1410 8bc6 7202 8b06 6a00 6a00 }
            // n = 7, score = 300
            //   e8????????           |                     
            //   837e1410             | cmp                 dword ptr [esi + 0x14], 0x10
            //   8bc6                 | mov                 eax, esi
            //   7202                 | jb                  4
            //   8b06                 | mov                 eax, dword ptr [esi]
            //   6a00                 | push                0
            //   6a00                 | push                0

        $sequence_5 = { f7d8 3bd0 737c 8d42ff 33d2 03c6 f7f6 }
            // n = 7, score = 300
            //   f7d8                 | neg                 eax
            //   3bd0                 | cmp                 edx, eax
            //   737c                 | jae                 0x7e
            //   8d42ff               | lea                 eax, [edx - 1]
            //   33d2                 | xor                 edx, edx
            //   03c6                 | add                 eax, esi
            //   f7f6                 | div                 esi

        $sequence_6 = { ffb52ceeffff 50 8d8560ffffff 50 ff9510eeffff 83c41c c645fc0a }
            // n = 7, score = 300
            //   ffb52ceeffff         | push                dword ptr [ebp - 0x11d4]
            //   50                   | push                eax
            //   8d8560ffffff         | lea                 eax, [ebp - 0xa0]
            //   50                   | push                eax
            //   ff9510eeffff         | call                dword ptr [ebp - 0x11f0]
            //   83c41c               | add                 esp, 0x1c
            //   c645fc0a             | mov                 byte ptr [ebp - 4], 0xa

        $sequence_7 = { f7470c00040000 740b 8b9f80020000 895d08 eb0e 57 e8???????? }
            // n = 7, score = 300
            //   f7470c00040000       | test                dword ptr [edi + 0xc], 0x400
            //   740b                 | je                  0xd
            //   8b9f80020000         | mov                 ebx, dword ptr [edi + 0x280]
            //   895d08               | mov                 dword ptr [ebp + 8], ebx
            //   eb0e                 | jmp                 0x10
            //   57                   | push                edi
            //   e8????????           |                     

        $sequence_8 = { ffb568ffffff 6a00 8b08 50 ff5114 8b4f24 8d573c }
            // n = 7, score = 300
            //   ffb568ffffff         | push                dword ptr [ebp - 0x98]
            //   6a00                 | push                0
            //   8b08                 | mov                 ecx, dword ptr [eax]
            //   50                   | push                eax
            //   ff5114               | call                dword ptr [ecx + 0x14]
            //   8b4f24               | mov                 ecx, dword ptr [edi + 0x24]
            //   8d573c               | lea                 edx, [edi + 0x3c]

        $sequence_9 = { ff7010 52 e8???????? 8d4358 8d4f58 3bc8 7413 }
            // n = 7, score = 300
            //   ff7010               | push                dword ptr [eax + 0x10]
            //   52                   | push                edx
            //   e8????????           |                     
            //   8d4358               | lea                 eax, [ebx + 0x58]
            //   8d4f58               | lea                 ecx, [edi + 0x58]
            //   3bc8                 | cmp                 ecx, eax
            //   7413                 | je                  0x15

    condition:
        7 of them and filesize < 26230784
}

rule win_metastealer_w0 {
    meta:
        description = "MetaStealer Memory"
        author = "Peter Gurney"
        date = "2022-04-29"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.metastealer"
        malpedia_rule_date = "20230119"
        malpedia_hash = ""
        malpedia_version = "20230131"
        malpedia_license = "CC BY-NC-SA 4.0"
        malpedia_sharing = "TLP:WHITE"
    strings:
        $str_c2_parse = {B8 56 55 55 55 F7 6D C4 8B C2 C1 E8 1F 03 C2 8B 55 C0 8D 04 40 2B 45 C4}
        $str_filename = ".xyz -newname hyper-v.exe" fullword wide
        $str_stackstring = {FF FF FF C7 85 ?? ?? ?? ?? ?? ?? ?? ?? C7 85 ?? ?? ?? ?? ?? ?? ?? ?? C7 85 ?? ?? ?? ?? ?? ?? ?? ?? C7 85 ?? ?? ?? ?? ?? ?? ?? ?? 66 0F EF}
    condition:
        uint16(0) == 0x5a4d and
        2 of ($str_*)
}