SYMBOLCOMMON_NAMEaka. SYNONYMS
win.boldmove (Back to overview)

BOLDMOVE


According to Mandiant, this malware family is attributed to potential chinese background and its Linux variant is related to exploitation of Fortinet's SSL-VPN (CVE-2022-42475).

References
2023-01-20The Hacker NewsRavie Lakshmanan
@online{lakshmanan:20230120:chinese:4df7900, author = {Ravie Lakshmanan}, title = {{Chinese Hackers Exploited Recent Fortinet Flaw as 0-Day to Drop Malware}}, date = {2023-01-20}, organization = {The Hacker News}, url = {https://thehackernews.com/2023/01/new-chinese-malware-spotted-exploiting.html}, language = {English}, urldate = {2023-01-20} } Chinese Hackers Exploited Recent Fortinet Flaw as 0-Day to Drop Malware
BOLDMOVE BOLDMOVE
2023-01-19MandiantScott Henderson, Cristiana Kittner, Sarah Hawley, Mark Lechtik
@online{henderson:20230119:suspected:39b0731, author = {Scott Henderson and Cristiana Kittner and Sarah Hawley and Mark Lechtik}, title = {{Suspected Chinese Threat Actors Exploiting FortiOS Vulnerability (CVE-2022-42475)}}, date = {2023-01-19}, organization = {Mandiant}, url = {https://www.mandiant.com/resources/blog/chinese-actors-exploit-fortios-flaw}, language = {English}, urldate = {2023-01-20} } Suspected Chinese Threat Actors Exploiting FortiOS Vulnerability (CVE-2022-42475)
BOLDMOVE BOLDMOVE
Yara Rules
[TLP:WHITE] win_boldmove_auto (20230715 | Detects win.boldmove.)
rule win_boldmove_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-07-11"
        version = "1"
        description = "Detects win.boldmove."
        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.boldmove"
        malpedia_rule_date = "20230705"
        malpedia_hash = "42d0574f4405bd7d2b154d321d345acb18834a41"
        malpedia_version = "20230715"
        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 = { 894c242c 8d4aff 66894c243a 8b4c242c 09e9 0f8435010000 0fb74c243a }
            // n = 7, score = 100
            //   894c242c             | mov                 dword ptr [esp + 0x2c], ecx
            //   8d4aff               | lea                 ecx, [edx - 1]
            //   66894c243a           | mov                 word ptr [esp + 0x3a], cx
            //   8b4c242c             | mov                 ecx, dword ptr [esp + 0x2c]
            //   09e9                 | or                  ecx, ebp
            //   0f8435010000         | je                  0x13b
            //   0fb74c243a           | movzx               ecx, word ptr [esp + 0x3a]

        $sequence_1 = { 5d c3 55 89e5 83ec18 8b4508 89442404 }
            // n = 7, score = 100
            //   5d                   | pop                 ebp
            //   c3                   | ret                 
            //   55                   | push                ebp
            //   89e5                 | mov                 ebp, esp
            //   83ec18               | sub                 esp, 0x18
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]
            //   89442404             | mov                 dword ptr [esp + 4], eax

        $sequence_2 = { e9???????? 8d4c2470 0fb64601 c744247000000000 89de 894c2430 }
            // n = 6, score = 100
            //   e9????????           |                     
            //   8d4c2470             | lea                 ecx, [esp + 0x70]
            //   0fb64601             | movzx               eax, byte ptr [esi + 1]
            //   c744247000000000     | mov                 dword ptr [esp + 0x70], 0
            //   89de                 | mov                 esi, ebx
            //   894c2430             | mov                 dword ptr [esp + 0x30], ecx

        $sequence_3 = { 8b742418 8d56fd 83e2fd 0f84cf060000 8b4c2460 8b7c2440 }
            // n = 6, score = 100
            //   8b742418             | mov                 esi, dword ptr [esp + 0x18]
            //   8d56fd               | lea                 edx, [esi - 3]
            //   83e2fd               | and                 edx, 0xfffffffd
            //   0f84cf060000         | je                  0x6d5
            //   8b4c2460             | mov                 ecx, dword ptr [esp + 0x60]
            //   8b7c2440             | mov                 edi, dword ptr [esp + 0x40]

        $sequence_4 = { 8d5870 895da4 8b75c0 397510 0f869b020000 8378403f 0f8677020000 }
            // n = 7, score = 100
            //   8d5870               | lea                 ebx, [eax + 0x70]
            //   895da4               | mov                 dword ptr [ebp - 0x5c], ebx
            //   8b75c0               | mov                 esi, dword ptr [ebp - 0x40]
            //   397510               | cmp                 dword ptr [ebp + 0x10], esi
            //   0f869b020000         | jbe                 0x2a1
            //   8378403f             | cmp                 dword ptr [eax + 0x40], 0x3f
            //   0f8677020000         | jbe                 0x27d

        $sequence_5 = { 8b4304 89442408 0fb64301 89442404 0fb603 890424 e8???????? }
            // n = 7, score = 100
            //   8b4304               | mov                 eax, dword ptr [ebx + 4]
            //   89442408             | mov                 dword ptr [esp + 8], eax
            //   0fb64301             | movzx               eax, byte ptr [ebx + 1]
            //   89442404             | mov                 dword ptr [esp + 4], eax
            //   0fb603               | movzx               eax, byte ptr [ebx]
            //   890424               | mov                 dword ptr [esp], eax
            //   e8????????           |                     

        $sequence_6 = { 0fb64901 0fb691608a4100 89d1 83e901 80f918 7744 }
            // n = 6, score = 100
            //   0fb64901             | movzx               ecx, byte ptr [ecx + 1]
            //   0fb691608a4100       | movzx               edx, byte ptr [ecx + 0x418a60]
            //   89d1                 | mov                 ecx, edx
            //   83e901               | sub                 ecx, 1
            //   80f918               | cmp                 cl, 0x18
            //   7744                 | ja                  0x46

        $sequence_7 = { 85db 0f84561d0000 81fe00040000 b800040000 0f4ec6 890424 89442440 }
            // n = 7, score = 100
            //   85db                 | test                ebx, ebx
            //   0f84561d0000         | je                  0x1d5c
            //   81fe00040000         | cmp                 esi, 0x400
            //   b800040000           | mov                 eax, 0x400
            //   0f4ec6               | cmovle              eax, esi
            //   890424               | mov                 dword ptr [esp], eax
            //   89442440             | mov                 dword ptr [esp + 0x40], eax

        $sequence_8 = { e9???????? 85c9 0f85a4030000 0fb64601 814c246800040000 89de e9???????? }
            // n = 7, score = 100
            //   e9????????           |                     
            //   85c9                 | test                ecx, ecx
            //   0f85a4030000         | jne                 0x3aa
            //   0fb64601             | movzx               eax, byte ptr [esi + 1]
            //   814c246800040000     | or                  dword ptr [esp + 0x68], 0x400
            //   89de                 | mov                 esi, ebx
            //   e9????????           |                     

        $sequence_9 = { 31ff 3c54 754d 83bcbe8800000000 0f84e1000000 47 83ff10 }
            // n = 7, score = 100
            //   31ff                 | xor                 edi, edi
            //   3c54                 | cmp                 al, 0x54
            //   754d                 | jne                 0x4f
            //   83bcbe8800000000     | cmp                 dword ptr [esi + edi*4 + 0x88], 0
            //   0f84e1000000         | je                  0xe7
            //   47                   | inc                 edi
            //   83ff10               | cmp                 edi, 0x10

    condition:
        7 of them and filesize < 242688
}
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