SYMBOLCOMMON_NAMEaka. SYNONYMS
win.grabbot (Back to overview)

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References
2017-03-17FortinetDavid Wang, He Xu
@online{wang:20170317:grabbot:e8dde0d, author = {David Wang and He Xu}, title = {{Grabbot is Back to Nab Your Data}}, date = {2017-03-17}, organization = {Fortinet}, url = {http://blog.fortinet.com/2017/03/17/grabbot-is-back-to-nab-your-data}, language = {English}, urldate = {2020-01-06} } Grabbot is Back to Nab Your Data
GrabBot
Yara Rules
[TLP:WHITE] win_grabbot_auto (20201014 | autogenerated rule brought to you by yara-signator)
rule win_grabbot_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-10-14"
        version = "1"
        description = "autogenerated rule brought to you by yara-signator"
        tool = "yara-signator v0.5.0"
        tool_config = "callsandjumps;datarefs;binvalue"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.grabbot"
        malpedia_rule_date = "20201014"
        malpedia_hash = "a7e3bd57eaf12bf3ea29a863c041091ba3af9ac9"
        malpedia_version = "20201014"
        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 = { 83f85a 770d 83f841 7208 83c020 }
            // n = 5, score = 3300
            //   83f85a               | cmp                 eax, 0x5a
            //   770d                 | ja                  0xf
            //   83f841               | cmp                 eax, 0x41
            //   7208                 | jb                  0xa
            //   83c020               | add                 eax, 0x20

        $sequence_1 = { 0fb702 83f85a 770b 83f841 7206 }
            // n = 5, score = 3300
            //   0fb702               | movzx               eax, word ptr [edx]
            //   83f85a               | cmp                 eax, 0x5a
            //   770b                 | ja                  0xd
            //   83f841               | cmp                 eax, 0x41
            //   7206                 | jb                  8

        $sequence_2 = { 83f841 7206 83c020 0fb7c0 83c202 }
            // n = 5, score = 3300
            //   83f841               | cmp                 eax, 0x41
            //   7206                 | jb                  8
            //   83c020               | add                 eax, 0x20
            //   0fb7c0               | movzx               eax, ax
            //   83c202               | add                 edx, 2

        $sequence_3 = { 0f850c010000 8b8890000000 85c9 0f84fe000000 }
            // n = 4, score = 3200
            //   0f850c010000         | jne                 0x112
            //   8b8890000000         | mov                 ecx, dword ptr [eax + 0x90]
            //   85c9                 | test                ecx, ecx
            //   0f84fe000000         | je                  0x104

        $sequence_4 = { 773f 81ec80000000 8bdc 53 8bc8 8a01 }
            // n = 6, score = 3200
            //   773f                 | ja                  0x41
            //   81ec80000000         | sub                 esp, 0x80
            //   8bdc                 | mov                 ebx, esp
            //   53                   | push                ebx
            //   8bc8                 | mov                 ecx, eax
            //   8a01                 | mov                 al, byte ptr [ecx]

        $sequence_5 = { 85c9 7419 8bc1 8d4900 }
            // n = 4, score = 3200
            //   85c9                 | test                ecx, ecx
            //   7419                 | je                  0x1b
            //   8bc1                 | mov                 eax, ecx
            //   8d4900               | lea                 ecx, [ecx]

        $sequence_6 = { e8???????? 8bc8 8d45d0 e8???????? 8945e8 e8???????? }
            // n = 6, score = 3200
            //   e8????????           |                     
            //   8bc8                 | mov                 ecx, eax
            //   8d45d0               | lea                 eax, [ebp - 0x30]
            //   e8????????           |                     
            //   8945e8               | mov                 dword ptr [ebp - 0x18], eax
            //   e8????????           |                     

        $sequence_7 = { 66833c7700 8d0477 75e1 8b45fc 81f15e7bec03 }
            // n = 5, score = 3200
            //   66833c7700           | cmp                 word ptr [edi + esi*2], 0
            //   8d0477               | lea                 eax, [edi + esi*2]
            //   75e1                 | jne                 0xffffffe3
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]
            //   81f15e7bec03         | xor                 ecx, 0x3ec7b5e

        $sequence_8 = { 56 ffd0 33c9 66894c37fe }
            // n = 4, score = 2300
            //   56                   | push                esi
            //   ffd0                 | call                eax
            //   33c9                 | xor                 ecx, ecx
            //   66894c37fe           | mov                 word ptr [edi + esi - 2], cx

        $sequence_9 = { 8b0d???????? 89480c e9???????? 33c0 e9???????? }
            // n = 5, score = 2000
            //   8b0d????????         |                     
            //   89480c               | mov                 dword ptr [eax + 0xc], ecx
            //   e9????????           |                     
            //   33c0                 | xor                 eax, eax
            //   e9????????           |                     

        $sequence_10 = { 7428 8b0d???????? 8908 8b0d???????? 894804 8b0d???????? 894808 }
            // n = 7, score = 2000
            //   7428                 | je                  0x2a
            //   8b0d????????         |                     
            //   8908                 | mov                 dword ptr [eax], ecx
            //   8b0d????????         |                     
            //   894804               | mov                 dword ptr [eax + 4], ecx
            //   8b0d????????         |                     
            //   894808               | mov                 dword ptr [eax + 8], ecx

        $sequence_11 = { 8d45f0 99 52 50 8b451c 99 }
            // n = 6, score = 1700
            //   8d45f0               | lea                 eax, [ebp - 0x10]
            //   99                   | cdq                 
            //   52                   | push                edx
            //   50                   | push                eax
            //   8b451c               | mov                 eax, dword ptr [ebp + 0x1c]
            //   99                   | cdq                 

        $sequence_12 = { 8bf0 85f6 741d 8d4601 50 e8???????? }
            // n = 6, score = 1700
            //   8bf0                 | mov                 esi, eax
            //   85f6                 | test                esi, esi
            //   741d                 | je                  0x1f
            //   8d4601               | lea                 eax, [esi + 1]
            //   50                   | push                eax
            //   e8????????           |                     

    condition:
        7 of them and filesize < 1335296
}
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