SYMBOLCOMMON_NAMEaka. SYNONYMS
win.matsnu (Back to overview)

Matsnu


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References
2015-05-15Check PointStanislav Skuratovich
@techreport{skuratovich:20150515:matsnu:850c41f, author = {Stanislav Skuratovich}, title = {{MATSNU}}, date = {2015-05-15}, institution = {Check Point}, url = {https://blog.checkpoint.com/wp-content/uploads/2015/07/matsnu-malwareid-technical-brief.pdf}, language = {English}, urldate = {2020-01-05} } MATSNU
Matsnu
Yara Rules
[TLP:WHITE] win_matsnu_auto (20220516 | Detects win.matsnu.)
rule win_matsnu_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-05-16"
        version = "1"
        description = "Detects win.matsnu."
        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.matsnu"
        malpedia_rule_date = "20220513"
        malpedia_hash = "7f4b2229e6ae614d86d74917f6d5b41890e62a26"
        malpedia_version = "20220516"
        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 = { 8b4dea b801000000 d3e0 0945e6 8b4db8 }
            // n = 5, score = 700
            //   8b4dea               | mov                 ecx, dword ptr [ebp - 0x16]
            //   b801000000           | mov                 eax, 1
            //   d3e0                 | shl                 eax, cl
            //   0945e6               | or                  dword ptr [ebp - 0x1a], eax
            //   8b4db8               | mov                 ecx, dword ptr [ebp - 0x48]

        $sequence_1 = { 50 f8 7201 c3 }
            // n = 4, score = 700
            //   50                   | push                eax
            //   f8                   | clc                 
            //   7201                 | jb                  3
            //   c3                   | ret                 

        $sequence_2 = { ebdb c745de00000000 8b45de 3b45ba 0f83eb010000 8b45c6 }
            // n = 6, score = 700
            //   ebdb                 | jmp                 0xffffffdd
            //   c745de00000000       | mov                 dword ptr [ebp - 0x22], 0
            //   8b45de               | mov                 eax, dword ptr [ebp - 0x22]
            //   3b45ba               | cmp                 eax, dword ptr [ebp - 0x46]
            //   0f83eb010000         | jae                 0x1f1
            //   8b45c6               | mov                 eax, dword ptr [ebp - 0x3a]

        $sequence_3 = { 817de6ff000000 7f0d 8b7dde 037d10 }
            // n = 4, score = 700
            //   817de6ff000000       | cmp                 dword ptr [ebp - 0x1a], 0xff
            //   7f0d                 | jg                  0xf
            //   8b7dde               | mov                 edi, dword ptr [ebp - 0x22]
            //   037d10               | add                 edi, dword ptr [ebp + 0x10]

        $sequence_4 = { 2945ce ebd3 c745d600000000 c745da00010000 }
            // n = 4, score = 700
            //   2945ce               | sub                 dword ptr [ebp - 0x32], eax
            //   ebd3                 | jmp                 0xffffffd5
            //   c745d600000000       | mov                 dword ptr [ebp - 0x2a], 0
            //   c745da00010000       | mov                 dword ptr [ebp - 0x26], 0x100

        $sequence_5 = { 80e1f0 c0e904 08c8 8d55bc 01c2 8a02 884701 }
            // n = 7, score = 700
            //   80e1f0               | and                 cl, 0xf0
            //   c0e904               | shr                 cl, 4
            //   08c8                 | or                  al, cl
            //   8d55bc               | lea                 edx, [ebp - 0x44]
            //   01c2                 | add                 edx, eax
            //   8a02                 | mov                 al, byte ptr [edx]
            //   884701               | mov                 byte ptr [edi + 1], al

        $sequence_6 = { 837d1002 7223 31c0 8a4601 240f c0e002 31c9 }
            // n = 7, score = 700
            //   837d1002             | cmp                 dword ptr [ebp + 0x10], 2
            //   7223                 | jb                  0x25
            //   31c0                 | xor                 eax, eax
            //   8a4601               | mov                 al, byte ptr [esi + 1]
            //   240f                 | and                 al, 0xf
            //   c0e002               | shl                 al, 2
            //   31c9                 | xor                 ecx, ecx

        $sequence_7 = { 7201 c3 ff6a00 6a00 6a03 6a00 6a00 }
            // n = 7, score = 700
            //   7201                 | jb                  3
            //   c3                   | ret                 
            //   ff6a00               | ljmp                [edx]
            //   6a00                 | push                0
            //   6a03                 | push                3
            //   6a00                 | push                0
            //   6a00                 | push                0

        $sequence_8 = { 31c0 eb70 ff75fc ff75f8 }
            // n = 4, score = 700
            //   31c0                 | xor                 eax, eax
            //   eb70                 | jmp                 0x72
            //   ff75fc               | push                dword ptr [ebp - 4]
            //   ff75f8               | push                dword ptr [ebp - 8]

        $sequence_9 = { 8b4db8 81e1ff000000 01c8 8945ee 8b45ee c1f803 }
            // n = 6, score = 700
            //   8b4db8               | mov                 ecx, dword ptr [ebp - 0x48]
            //   81e1ff000000         | and                 ecx, 0xff
            //   01c8                 | add                 eax, ecx
            //   8945ee               | mov                 dword ptr [ebp - 0x12], eax
            //   8b45ee               | mov                 eax, dword ptr [ebp - 0x12]
            //   c1f803               | sar                 eax, 3

    condition:
        7 of them and filesize < 606992
}
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