win.nymaim2 (Back to overview)

Nymaim2


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References
https://johannesbader.ch/2018/04/the-new-domain-generation-algorithm-of-nymaim/
Yara Rules
[TLP:WHITE] win_nymaim2_auto (20190620 | autogenerated rule brought to you by yara-signator)
rule win_nymaim2_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2019-07-05"
        version = "1"
        description = "autogenerated rule brought to you by yara-signator"
        tool = "yara-signator 0.2a"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.nymaim2"
        malpedia_version = "20190620"
        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 / approach 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 = { e8???????? 85db 8bf0 74?? 53 ff15???????? 85f6 }
            // n = 7, score = 200
            //   e8????????           |                     
            //   85db                 | test                ebx, ebx
            //   8bf0                 | mov                 esi, eax
            //   74??                 |                     
            //   53                   | push                ebx
            //   ff15????????         |                     
            //   85f6                 | test                esi, esi

        $sequence_1 = { ff5004 50 8bce e8???????? 50 ff35???????? e8???????? }
            // n = 7, score = 200
            //   ff5004               | call                dword ptr [eax + 4]
            //   50                   | push                eax
            //   8bce                 | mov                 ecx, esi
            //   e8????????           |                     
            //   50                   | push                eax
            //   ff35????????         |                     
            //   e8????????           |                     

        $sequence_2 = { e8???????? 8975f0 8065fc00 8d4d0c e8???????? 8b4df4 8b4508 }
            // n = 7, score = 200
            //   e8????????           |                     
            //   8975f0               | mov                 dword ptr [ebp - 0x10], esi
            //   8065fc00             | and                 byte ptr [ebp - 4], 0
            //   8d4d0c               | lea                 ecx, [ebp + 0xc]
            //   e8????????           |                     
            //   8b4df4               | mov                 ecx, dword ptr [ebp - 0xc]
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]

        $sequence_3 = { e8???????? 8d4dec 885dfc e8???????? 8065fc00 8d4d9c e8???????? }
            // n = 7, score = 200
            //   e8????????           |                     
            //   8d4dec               | lea                 ecx, [ebp - 0x14]
            //   885dfc               | mov                 byte ptr [ebp - 4], bl
            //   e8????????           |                     
            //   8065fc00             | and                 byte ptr [ebp - 4], 0
            //   8d4d9c               | lea                 ecx, [ebp - 0x64]
            //   e8????????           |                     

        $sequence_4 = { ff30 8d45f0 c645fc04 50 e8???????? 59 59 }
            // n = 7, score = 200
            //   ff30                 | push                dword ptr [eax]
            //   8d45f0               | lea                 eax, [ebp - 0x10]
            //   c645fc04             | mov                 byte ptr [ebp - 4], 4
            //   50                   | push                eax
            //   e8????????           |                     
            //   59                   | pop                 ecx
            //   59                   | pop                 ecx

        $sequence_5 = { e8???????? 83ec18 8d45c4 8bcc 8965ec 50 e8???????? }
            // n = 7, score = 200
            //   e8????????           |                     
            //   83ec18               | sub                 esp, 0x18
            //   8d45c4               | lea                 eax, [ebp - 0x3c]
            //   8bcc                 | mov                 ecx, esp
            //   8965ec               | mov                 dword ptr [ebp - 0x14], esp
            //   50                   | push                eax
            //   e8????????           |                     

        $sequence_6 = { e8???????? 8d8d64ffffff c645fc01 e8???????? 8d8d7cffffff 885dfc e8???????? }
            // n = 7, score = 200
            //   e8????????           |                     
            //   8d8d64ffffff         | lea                 ecx, [ebp - 0x9c]
            //   c645fc01             | mov                 byte ptr [ebp - 4], 1
            //   e8????????           |                     
            //   8d8d7cffffff         | lea                 ecx, [ebp - 0x84]
            //   885dfc               | mov                 byte ptr [ebp - 4], bl
            //   e8????????           |                     

        $sequence_7 = { e8???????? 8d4de0 c645fc05 e8???????? 6833010000 8d4ddc e8???????? }
            // n = 7, score = 200
            //   e8????????           |                     
            //   8d4de0               | lea                 ecx, [ebp - 0x20]
            //   c645fc05             | mov                 byte ptr [ebp - 4], 5
            //   e8????????           |                     
            //   6833010000           | push                0x133
            //   8d4ddc               | lea                 ecx, [ebp - 0x24]
            //   e8????????           |                     

        $sequence_8 = { e8???????? 8bc8 c645fc0f e8???????? 8945cc 8d4de8 c645fc10 }
            // n = 7, score = 200
            //   e8????????           |                     
            //   8bc8                 | mov                 ecx, eax
            //   c645fc0f             | mov                 byte ptr [ebp - 4], 0xf
            //   e8????????           |                     
            //   8945cc               | mov                 dword ptr [ebp - 0x34], eax
            //   8d4de8               | lea                 ecx, [ebp - 0x18]
            //   c645fc10             | mov                 byte ptr [ebp - 4], 0x10

        $sequence_9 = { e8???????? 8b06 53 50 8d4dd8 e8???????? 85c0 }
            // n = 7, score = 200
            //   e8????????           |                     
            //   8b06                 | mov                 eax, dword ptr [esi]
            //   53                   | push                ebx
            //   50                   | push                eax
            //   8d4dd8               | lea                 ecx, [ebp - 0x28]
            //   e8????????           |                     
            //   85c0                 | test                eax, eax

    condition:
        7 of them
}
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