SYMBOLCOMMON_NAMEaka. SYNONYMS
win.netkey (Back to overview)

NetKey


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References
2019-07-31Twitter (@KevinPerlow)Kevin Perlow
@online{perlow:20190731:dprk:5a12842, author = {Kevin Perlow}, title = {{Tweet on DPRK malware}}, date = {2019-07-31}, organization = {Twitter (@KevinPerlow)}, url = {https://twitter.com/kevinperlow/status/1156406115472760835}, language = {English}, urldate = {2020-01-08} } Tweet on DPRK malware
NetKey
Yara Rules
[TLP:WHITE] win_netkey_auto (20230407 | Detects win.netkey.)
rule win_netkey_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-03-28"
        version = "1"
        description = "Detects win.netkey."
        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.netkey"
        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 = { 8a4508 33ff c745fc00000000 8bcb }
            // n = 4, score = 200
            //   8a4508               | mov                 al, byte ptr [ebp + 8]
            //   33ff                 | xor                 edi, edi
            //   c745fc00000000       | mov                 dword ptr [ebp - 4], 0
            //   8bcb                 | mov                 ecx, ebx

        $sequence_1 = { 85c0 74ea 56 53 8d4728 899f2c200300 50 }
            // n = 7, score = 200
            //   85c0                 | test                eax, eax
            //   74ea                 | je                  0xffffffec
            //   56                   | push                esi
            //   53                   | push                ebx
            //   8d4728               | lea                 eax, [edi + 0x28]
            //   899f2c200300         | mov                 dword ptr [edi + 0x3202c], ebx
            //   50                   | push                eax

        $sequence_2 = { 83e13f c1f806 6bc930 8855d4 8b0485a8214400 88540828 8b0b }
            // n = 7, score = 200
            //   83e13f               | and                 ecx, 0x3f
            //   c1f806               | sar                 eax, 6
            //   6bc930               | imul                ecx, ecx, 0x30
            //   8855d4               | mov                 byte ptr [ebp - 0x2c], dl
            //   8b0485a8214400       | mov                 eax, dword ptr [eax*4 + 0x4421a8]
            //   88540828             | mov                 byte ptr [eax + ecx + 0x28], dl
            //   8b0b                 | mov                 ecx, dword ptr [ebx]

        $sequence_3 = { 741c 85db 7507 c74634142f4300 }
            // n = 4, score = 200
            //   741c                 | je                  0x1e
            //   85db                 | test                ebx, ebx
            //   7507                 | jne                 9
            //   c74634142f4300       | mov                 dword ptr [esi + 0x34], 0x432f14

        $sequence_4 = { e9???????? c745e0f4514300 e9???????? c745e00c524300 e9???????? c745e074534300 e9???????? }
            // n = 7, score = 200
            //   e9????????           |                     
            //   c745e0f4514300       | mov                 dword ptr [ebp - 0x20], 0x4351f4
            //   e9????????           |                     
            //   c745e00c524300       | mov                 dword ptr [ebp - 0x20], 0x43520c
            //   e9????????           |                     
            //   c745e074534300       | mov                 dword ptr [ebp - 0x20], 0x435374
            //   e9????????           |                     

        $sequence_5 = { c1fa06 6bc830 8b0495a8214400 8a440828 a848 7404 33c0 }
            // n = 7, score = 200
            //   c1fa06               | sar                 edx, 6
            //   6bc830               | imul                ecx, eax, 0x30
            //   8b0495a8214400       | mov                 eax, dword ptr [edx*4 + 0x4421a8]
            //   8a440828             | mov                 al, byte ptr [eax + ecx + 0x28]
            //   a848                 | test                al, 0x48
            //   7404                 | je                  6
            //   33c0                 | xor                 eax, eax

        $sequence_6 = { 6a0a 57 56 50 e8???????? 8bcf }
            // n = 6, score = 200
            //   6a0a                 | push                0xa
            //   57                   | push                edi
            //   56                   | push                esi
            //   50                   | push                eax
            //   e8????????           |                     
            //   8bcf                 | mov                 ecx, edi

        $sequence_7 = { 8b4514 40 c745ec47f04000 894df8 8945fc 64a100000000 8945e8 }
            // n = 7, score = 200
            //   8b4514               | mov                 eax, dword ptr [ebp + 0x14]
            //   40                   | inc                 eax
            //   c745ec47f04000       | mov                 dword ptr [ebp - 0x14], 0x40f047
            //   894df8               | mov                 dword ptr [ebp - 8], ecx
            //   8945fc               | mov                 dword ptr [ebp - 4], eax
            //   64a100000000         | mov                 eax, dword ptr fs:[0]
            //   8945e8               | mov                 dword ptr [ebp - 0x18], eax

        $sequence_8 = { 8bf8 83c424 85ff 751c 8b45f0 }
            // n = 5, score = 200
            //   8bf8                 | mov                 edi, eax
            //   83c424               | add                 esp, 0x24
            //   85ff                 | test                edi, edi
            //   751c                 | jne                 0x1e
            //   8b45f0               | mov                 eax, dword ptr [ebp - 0x10]

        $sequence_9 = { 0fb701 8d4902 6689440ffe 6685c0 75f0 8b4dfc b801000000 }
            // n = 7, score = 200
            //   0fb701               | movzx               eax, word ptr [ecx]
            //   8d4902               | lea                 ecx, [ecx + 2]
            //   6689440ffe           | mov                 word ptr [edi + ecx - 2], ax
            //   6685c0               | test                ax, ax
            //   75f0                 | jne                 0xfffffff2
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   b801000000           | mov                 eax, 1

    condition:
        7 of them and filesize < 606208
}
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