rule win_maskgramstealer_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.maskgramstealer."
        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.maskgramstealer"
        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 = { 7437 48833d????????00 742d 48833d????????00 }
            // n = 4, score = 200
            //   7437                 | dec                 eax
            //   48833d????????00     |                     
            //   742d                 | lea                 eax, [esp + 0x70]
            //   48833d????????00     |                     

        $sequence_1 = { 498d1400 8a02 3c5c 7404 }
            // n = 4, score = 200
            //   498d1400             | mov                 ecx, dword ptr [esp + 0x68]
            //   8a02                 | call                dword ptr [ebx]
            //   3c5c                 | dec                 eax
            //   7404                 | mov                 eax, dword ptr [ebx]

        $sequence_2 = { 498d1400 8a02 3c5c 7404 3c2f 7503 48ffc2 }
            // n = 7, score = 200
            //   498d1400             | pop                 eax
            //   8a02                 | dec                 eax
            //   3c5c                 | lea                 eax, [esp + 0x80]
            //   7404                 | mov                 dword ptr [esp + 0x30], esi
            //   3c2f                 | push                6
            //   7503                 | dec                 eax
            //   48ffc2               | mov                 edx, ebp

        $sequence_3 = { 4531c9 428a0409 468a040a 448d50bf 4180fa19 7703 }
            // n = 6, score = 200
            //   4531c9               | inc                 ecx
            //   428a0409             | pop                 eax
            //   468a040a             | dec                 eax
            //   448d50bf             | xchg                eax, ecx
            //   4180fa19             | xor                 eax, eax
            //   7703                 | push                3

        $sequence_4 = { 7404 39f0 7204 31c0 }
            // n = 4, score = 200
            //   7404                 | pop                 eax
            //   39f0                 | dec                 eax
            //   7204                 | lea                 edx, [esp + 0x30]
            //   31c0                 | push                0x12

        $sequence_5 = { 4180fa19 7703 83c020 458d50bf 4180fa19 7704 4183c020 }
            // n = 7, score = 200
            //   4180fa19             | inc                 ecx
            //   7703                 | pop                 eax
            //   83c020               | dec                 eax
            //   458d50bf             | lea                 ecx, [0x10105]
            //   4180fa19             | call                esi
            //   7704                 | push                0x13
            //   4183c020             | dec                 eax

        $sequence_6 = { 31c0 b980000000 803d????????00 f3ab }
            // n = 4, score = 200
            //   31c0                 | jle                 0xb36
            //   b980000000           | dec                 ebp
            //   803d????????00       |                     
            //   f3ab                 | arpl                sp, di

        $sequence_7 = { 4438c0 74ea 4429c0 c3 }
            // n = 4, score = 200
            //   4438c0               | ja                  0x151e
            //   74ea                 | dec                 ecx
            //   4429c0               | mov                 edx, 0x7e03ff
            //   c3                   | add                 byte ptr [eax], al

        $sequence_8 = { c3 803900 7405 48ffc1 ebf6 31c0 448a0402 }
            // n = 7, score = 200
            //   c3                   | dec                 eax
            //   803900               | mov                 dword ptr [esp + 0x20], eax
            //   7405                 | dec                 eax
            //   48ffc1               | lea                 eax, [esp + 0xa8]
            //   ebf6                 | mov                 ecx, ebp
            //   31c0                 | dec                 eax
            //   448a0402             | mov                 edx, eax

        $sequence_9 = { 48833d????????00 488905???????? 7437 48833d????????00 }
            // n = 4, score = 200
            //   48833d????????00     |                     
            //   488905????????       |                     
            //   7437                 | dec                 eax
            //   48833d????????00     |                     

    condition:
        7 of them and filesize < 353280
}