Karius (Malware Family)

Karius

VTCollection
According to checkpoint, Karius is a banking trojan in development, borrowing code from Ramnit, Vawtrack as well as Trickbot, currently implementing webinject attacks only.
It comes with an injector that loads an intermediate "proxy" component, which in turn loads the actual banker component.
Communication with the c2 are in json format and encrypted with RC4 with a hardcoded key.
In the initial version, observed in March 2018, the webinjects were hardcoded in the binary, while in subsequent versions, they were received by the c2.
References

2022-08-18 ⋅ IBM ⋅ Charlotte Hammond, Ole Villadsen
From Ramnit To Bumblebee (via NeverQuest): Similarities and Code Overlap Shed Light On Relationships Between Malware Developers
BumbleBee Karius Ramnit TrickBot Vawtrak
2018-06-06 ⋅ Check Point ⋅ Check Point Research
Banking Trojans Under Development
Karius
2018-03-28 ⋅ Malwrologist
Multi-stage Powershell script (Brownies)
Karius
Yara Rules

[TLP:WHITE] win_karius_auto (20260917 | Detects win.karius.)
rule win_karius_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.karius."
        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.karius"
        malpedia_rule_date = "20260916"
        malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6"
        malpedia_version = "20260917"
        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 = { 85db 0f8477000000 8bb424b0000000 418b10 }
            // n = 4, score = 400
            //   85db                 | je                  0x9d
            //   0f8477000000         | dec                 ecx
            //   8bb424b0000000       | mov                 ecx, esi
            //   418b10               | call                ebx

        $sequence_1 = { 8bb424b0000000 418b10 8bcd 4903d6 0fb602 }
            // n = 5, score = 400
            //   8bb424b0000000       | mov                 edx, dword ptr [eax]
            //   418b10               | mov                 ecx, ebp
            //   8bcd                 | dec                 ecx
            //   4903d6               | add                 edx, esi
            //   0fb602               | movzx               eax, byte ptr [edx]

        $sequence_2 = { 498bce ffd3 4183bf8c00000000 0f84b3000000 458b9f88000000 }
            // n = 5, score = 400
            //   498bce               | mov                 ebx, dword ptr [ebx + 0x18]
            //   ffd3                 | test                ebx, ebx
            //   4183bf8c00000000     | je                  0xa5
            //   0f84b3000000         | inc                 ecx
            //   458b9f88000000       | cmp                 dword ptr [ebx + 0x14], 0

        $sequence_3 = { 488b05???????? 4885c0 7512 ff15???????? 488905???????? }
            // n = 5, score = 400
            //   488b05????????       |                     
            //   4885c0               | inc                 ecx
            //   7512                 | cmp                 dword ptr [ebx + 0x14], 0
            //   ff15????????         |                     
            //   488905????????       |                     

        $sequence_4 = { 0f8492000000 458b4320 458b5324 33ed }
            // n = 4, score = 400
            //   0f8492000000         | dec                 ebp
            //   458b4320             | add                 ebx, esi
            //   458b5324             | inc                 ecx
            //   33ed                 | mov                 ebx, dword ptr [ebx + 0x18]

        $sequence_5 = { 41b830000000 488bcf ff15???????? 4885c0 }
            // n = 4, score = 400
            //   41b830000000         | mov                 ecx, esi
            //   488bcf               | call                ebx
            //   ff15????????         |                     
            //   4885c0               | inc                 ecx

        $sequence_6 = { 418b5b18 85db 0f849d000000 41837b1400 0f8492000000 }
            // n = 5, score = 400
            //   418b5b18             | inc                 ecx
            //   85db                 | mov                 ebx, dword ptr [ebx + 0x18]
            //   0f849d000000         | test                ebx, ebx
            //   41837b1400           | je                  0xa3
            //   0f8492000000         | inc                 ecx

        $sequence_7 = { c3 85c0 7505 e8???????? b801000000 }
            // n = 5, score = 400
            //   c3                   | inc                 ecx
            //   85c0                 | mov                 ebx, dword ptr [ebx + 0x18]
            //   7505                 | test                ebx, ebx
            //   e8????????           |                     
            //   b801000000           | je                  0xa5

        $sequence_8 = { 33ed 4d03c6 4d03d6 448bcd 85db 0f8477000000 }
            // n = 6, score = 400
            //   33ed                 | mov                 edx, dword ptr [ebx + 0x24]
            //   4d03c6               | dec                 ebp
            //   4d03d6               | add                 edx, esi
            //   448bcd               | inc                 esp
            //   85db                 | mov                 ecx, ebp
            //   0f8477000000         | test                ebx, ebx

        $sequence_9 = { 488bc8 ff15???????? 4c8be8 498bce ff15???????? }
            // n = 5, score = 300
            //   488bc8               | mov                 ecx, ebp
            //   ff15????????         |                     
            //   4c8be8               | dec                 ecx
            //   498bce               | add                 edx, esi
            //   ff15????????         |                     

        $sequence_10 = { 4d8bcf 33d2 41b800001000 488bce }
            // n = 4, score = 300
            //   4d8bcf               | je                  0xa3
            //   33d2                 | inc                 ecx
            //   41b800001000         | cmp                 dword ptr [ebx + 0x14], 0
            //   488bce               | je                  0x9d

        $sequence_11 = { 8bf0 83c40c 85f6 7427 8bff 8a06 84c0 }
            // n = 7, score = 300
            //   8bf0                 | je                  0xac
            //   83c40c               | inc                 ecx
            //   85f6                 | cmp                 dword ptr [ebx + 0x14], 0
            //   7427                 | je                  0xac
            //   8bff                 | je                  0xa3
            //   8a06                 | inc                 ecx
            //   84c0                 | cmp                 dword ptr [ebx + 0x14], 0

        $sequence_12 = { 3c66 0f8fa2000000 0fbec8 83e957 }
            // n = 4, score = 300
            //   3c66                 | call                ebx
            //   0f8fa2000000         | inc                 ecx
            //   0fbec8               | cmp                 dword ptr [edi + 0x8c], 0
            //   83e957               | je                  0xd5

        $sequence_13 = { 3c30 7c04 3c39 7ee3 803f2e 752c 8a4701 }
            // n = 7, score = 300
            //   3c30                 | dec                 eax
            //   7c04                 | test                eax, eax
            //   3c39                 | jne                 0x17
            //   7ee3                 | inc                 ecx
            //   803f2e               | mov                 ebx, dword ptr [ebx + 0x18]
            //   752c                 | test                ebx, ebx
            //   8a4701               | je                  0xa3

        $sequence_14 = { 7405 f60001 7502 33c0 }
            // n = 4, score = 300
            //   7405                 | inc                 ecx
            //   f60001               | cmp                 dword ptr [ebx + 0x14], 0
            //   7502                 | dec                 eax
            //   33c0                 | test                eax, eax

        $sequence_15 = { eb06 803900 0f94c0 84c0 0f85a1000000 8a6514 }
            // n = 6, score = 300
            //   eb06                 | inc                 ecx
            //   803900               | cmp                 dword ptr [ebx + 0x14], 0
            //   0f94c0               | je                  0xa3
            //   84c0                 | dec                 esp
            //   0f85a1000000         | mov                 eax, dword ptr [esp + 0xa0]
            //   8a6514               | mov                 edi, 1

        $sequence_16 = { ff15???????? 488bf8 4885c0 7505 8d4701 }
            // n = 5, score = 300
            //   ff15????????         |                     
            //   488bf8               | add                 edx, esi
            //   4885c0               | inc                 esp
            //   7505                 | mov                 ecx, ebp
            //   8d4701               | test                ebx, ebx

        $sequence_17 = { 33d2 488bce ff15???????? 4c8bf0 }
            // n = 4, score = 300
            //   33d2                 | mov                 ecx, ebp
            //   488bce               | dec                 ecx
            //   ff15????????         |                     
            //   4c8bf0               | add                 edx, esi

        $sequence_18 = { 803e5d 7508 5f 5b 8d4601 5e }
            // n = 6, score = 300
            //   803e5d               | cmp                 dword ptr [edi + 0x8c], 0
            //   7508                 | inc                 ecx
            //   5f                   | cmp                 dword ptr [edi + 0x8c], 0
            //   5b                   | je                  0xc1
            //   8d4601               | inc                 ebp
            //   5e                   | mov                 ebx, dword ptr [edi + 0x88]

        $sequence_19 = { 488d4b10 488d542450 41b804000000 c6430f68 }
            // n = 4, score = 300
            //   488d4b10             | inc                 ebp
            //   488d542450           | mov                 ebx, dword ptr [edi + 0x88]
            //   41b804000000         | dec                 ebp
            //   c6430f68             | add                 ebx, esi

        $sequence_20 = { d9ca d8c9 dec2 3c30 7c04 3c39 }
            // n = 6, score = 300
            //   d9ca                 | je                  0x9d
            //   d8c9                 | inc                 ebp
            //   dec2                 | mov                 eax, dword ptr [ebx + 0x20]
            //   3c30                 | inc                 ebp
            //   7c04                 | mov                 edx, dword ptr [ebx + 0x24]
            //   3c39                 | dec                 ecx

        $sequence_21 = { 6683f809 7505 8d7b02 eb09 6685c0 }
            // n = 5, score = 300
            //   6683f809             | inc                 ecx
            //   7505                 | mov                 ebx, dword ptr [ebx + 0x18]
            //   8d7b02               | test                ebx, ebx
            //   eb09                 | je                  0x7d
            //   6685c0               | mov                 esi, dword ptr [esp + 0xb0]

        $sequence_22 = { 8806 8ac2 4e 243f 0c80 c1ea06 8806 }
            // n = 7, score = 300
            //   8806                 | jne                 0x17
            //   8ac2                 | dec                 esp
            //   4e                   | mov                 eax, dword ptr [esp + 0xa0]
            //   243f                 | mov                 edi, 1
            //   0c80                 | mov                 edx, edi
            //   c1ea06               | dec                 ecx
            //   8806                 | mov                 ecx, esi

        $sequence_23 = { 4d8bcc 4d8bc7 488bd0 488bce }
            // n = 4, score = 300
            //   4d8bcc               | je                  0x7d
            //   4d8bc7               | mov                 esi, dword ptr [esp + 0xb0]
            //   488bd0               | inc                 ecx
            //   488bce               | mov                 edx, dword ptr [eax]

        $sequence_24 = { 85c9 7521 85c0 750f ff15???????? a3???????? 85c0 }
            // n = 7, score = 300
            //   85c9                 | mov                 edx, edi
            //   7521                 | dec                 ecx
            //   85c0                 | mov                 ecx, esi
            //   750f                 | call                ebx
            //   ff15????????         |                     
            //   a3????????           |                     
            //   85c0                 | inc                 ecx

        $sequence_25 = { 8bc7 ffc8 7416 ffc8 7522 }
            // n = 5, score = 300
            //   8bc7                 | inc                 ecx
            //   ffc8                 | mov                 ebx, dword ptr [ebx + 0x18]
            //   7416                 | mov                 esi, dword ptr [esp + 0xb0]
            //   ffc8                 | inc                 ecx
            //   7522                 | mov                 edx, dword ptr [eax]

    condition:
        7 of them and filesize < 434176
}
Download all Yara Rules
Karius Propose Change

References

Yara Rules

Karius
