SYMBOLCOMMON_NAMEaka. SYNONYMS
win.ketrum (Back to overview)

Ketrum

Actor(s): Mirage


Intezer found this family mid May 2020, which appears to be a merger of the family Ketrican and Okrum.

References
2020-05-21IntezerPaul Litvak
@online{litvak:20200521:evolution:a14bf60, author = {Paul Litvak}, title = {{The Evolution of APT15’s Codebase 2020}}, date = {2020-05-21}, organization = {Intezer}, url = {https://www.intezer.com/blog/research/the-evolution-of-apt15s-codebase-2020/}, language = {English}, urldate = {2020-05-23} } The Evolution of APT15’s Codebase 2020
Ketrican Ketrum Okrum
Yara Rules
[TLP:WHITE] win_ketrum_auto (20220516 | Detects win.ketrum.)
rule win_ketrum_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-05-16"
        version = "1"
        description = "Detects win.ketrum."
        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.ketrum"
        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 = { 8d85fcf7ffff 83c418 8d7801 8a08 40 }
            // n = 5, score = 200
            //   8d85fcf7ffff         | lea                 eax, [ebp - 0x804]
            //   83c418               | add                 esp, 0x18
            //   8d7801               | lea                 edi, [eax + 1]
            //   8a08                 | mov                 cl, byte ptr [eax]
            //   40                   | inc                 eax

        $sequence_1 = { 85c0 744d b9???????? 8bc1 8d7001 8a10 }
            // n = 6, score = 200
            //   85c0                 | test                eax, eax
            //   744d                 | je                  0x4f
            //   b9????????           |                     
            //   8bc1                 | mov                 eax, ecx
            //   8d7001               | lea                 esi, [eax + 1]
            //   8a10                 | mov                 dl, byte ptr [eax]

        $sequence_2 = { 0345e0 8919 8d843891d386eb c1c80b 034104 03c6 }
            // n = 6, score = 200
            //   0345e0               | add                 eax, dword ptr [ebp - 0x20]
            //   8919                 | mov                 dword ptr [ecx], ebx
            //   8d843891d386eb       | lea                 eax, [eax + edi - 0x14792c6f]
            //   c1c80b               | ror                 eax, 0xb
            //   034104               | add                 eax, dword ptr [ecx + 4]
            //   03c6                 | add                 eax, esi

        $sequence_3 = { 8d85fcdfffff 50 ff15???????? 8b4dfc 5f }
            // n = 5, score = 200
            //   8d85fcdfffff         | lea                 eax, [ebp - 0x2004]
            //   50                   | push                eax
            //   ff15????????         |                     
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   5f                   | pop                 edi

        $sequence_4 = { a1???????? 33c5 8945fc 807e6800 }
            // n = 4, score = 200
            //   a1????????           |                     
            //   33c5                 | xor                 eax, ebp
            //   8945fc               | mov                 dword ptr [ebp - 4], eax
            //   807e6800             | cmp                 byte ptr [esi + 0x68], 0

        $sequence_5 = { 8bf0 83e61f 8d3c8da0bc6200 8b0f }
            // n = 4, score = 200
            //   8bf0                 | mov                 esi, eax
            //   83e61f               | and                 esi, 0x1f
            //   8d3c8da0bc6200       | lea                 edi, [ecx*4 + 0x62bca0]
            //   8b0f                 | mov                 ecx, dword ptr [edi]

        $sequence_6 = { 56 33c0 57 0fb7d0 8bc2 6a20 c1e210 }
            // n = 7, score = 200
            //   56                   | push                esi
            //   33c0                 | xor                 eax, eax
            //   57                   | push                edi
            //   0fb7d0               | movzx               edx, ax
            //   8bc2                 | mov                 eax, edx
            //   6a20                 | push                0x20
            //   c1e210               | shl                 edx, 0x10

        $sequence_7 = { ff35???????? 33c0 0fb7d0 8bc2 c1e210 }
            // n = 5, score = 200
            //   ff35????????         |                     
            //   33c0                 | xor                 eax, eax
            //   0fb7d0               | movzx               edx, ax
            //   8bc2                 | mov                 eax, edx
            //   c1e210               | shl                 edx, 0x10

        $sequence_8 = { 6802100000 ffb538efffff ff15???????? 85c0 750c ff15???????? }
            // n = 6, score = 100
            //   6802100000           | push                0x1002
            //   ffb538efffff         | push                dword ptr [ebp - 0x10c8]
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   750c                 | jne                 0xe
            //   ff15????????         |                     

        $sequence_9 = { 84c0 75e9 5e c3 55 8bec }
            // n = 6, score = 100
            //   84c0                 | test                al, al
            //   75e9                 | jne                 0xffffffeb
            //   5e                   | pop                 esi
            //   c3                   | ret                 
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp

        $sequence_10 = { 8985c4fdffff ff15???????? 8b35???????? 53 8985ccfdffff ffd6 }
            // n = 6, score = 100
            //   8985c4fdffff         | mov                 dword ptr [ebp - 0x23c], eax
            //   ff15????????         |                     
            //   8b35????????         |                     
            //   53                   | push                ebx
            //   8985ccfdffff         | mov                 dword ptr [ebp - 0x234], eax
            //   ffd6                 | call                esi

        $sequence_11 = { 50 e8???????? 83c410 8bd8 8d85c4fdffff }
            // n = 5, score = 100
            //   50                   | push                eax
            //   e8????????           |                     
            //   83c410               | add                 esp, 0x10
            //   8bd8                 | mov                 ebx, eax
            //   8d85c4fdffff         | lea                 eax, [ebp - 0x23c]

        $sequence_12 = { ff15???????? ffb5ccfdffff ff15???????? 8b4dfc 33c0 399dd4fdffff }
            // n = 6, score = 100
            //   ff15????????         |                     
            //   ffb5ccfdffff         | push                dword ptr [ebp - 0x234]
            //   ff15????????         |                     
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   33c0                 | xor                 eax, eax
            //   399dd4fdffff         | cmp                 dword ptr [ebp - 0x22c], ebx

        $sequence_13 = { e8???????? 8b4e18 894804 ff4618 6a10 e8???????? }
            // n = 6, score = 100
            //   e8????????           |                     
            //   8b4e18               | mov                 ecx, dword ptr [esi + 0x18]
            //   894804               | mov                 dword ptr [eax + 4], ecx
            //   ff4618               | inc                 dword ptr [esi + 0x18]
            //   6a10                 | push                0x10
            //   e8????????           |                     

        $sequence_14 = { c705????????feaf4000 8935???????? a3???????? ff15???????? a3???????? 83f8ff }
            // n = 6, score = 100
            //   c705????????feaf4000     |     
            //   8935????????         |                     
            //   a3????????           |                     
            //   ff15????????         |                     
            //   a3????????           |                     
            //   83f8ff               | cmp                 eax, -1

        $sequence_15 = { 56 8d5002 57 668b30 83c002 }
            // n = 5, score = 100
            //   56                   | push                esi
            //   8d5002               | lea                 edx, [eax + 2]
            //   57                   | push                edi
            //   668b30               | mov                 si, word ptr [eax]
            //   83c002               | add                 eax, 2

    condition:
        7 of them and filesize < 4599808
}
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