Actor(s): APT41, Aurora Panda, Leviathan
a backdoor that obfuscates its communications as normal traffic to legitimate websites such as Github and Microsoft's Technet portal.
rule win_blackcoffee_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-12-06" version = "1" description = "Detects win.blackcoffee." 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.blackcoffee" malpedia_rule_date = "20231130" malpedia_hash = "fc8a0e9f343f6d6ded9e7df1a64dac0cc68d7351" malpedia_version = "20230808" 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 = { 8d85b4feffff 50 ff75f8 ff15???????? 8b85b4feffff } // n = 5, score = 200 // 8d85b4feffff | lea eax, [ebp - 0x14c] // 50 | push eax // ff75f8 | push dword ptr [ebp - 8] // ff15???????? | // 8b85b4feffff | mov eax, dword ptr [ebp - 0x14c] $sequence_1 = { 8b35???????? 57 33ff 3bc7 7416 57 50 } // n = 7, score = 200 // 8b35???????? | // 57 | push edi // 33ff | xor edi, edi // 3bc7 | cmp eax, edi // 7416 | je 0x18 // 57 | push edi // 50 | push eax $sequence_2 = { 8b45fc 83c424 8d44301a 6a1c 6a40 894508 ff15???????? } // n = 7, score = 200 // 8b45fc | mov eax, dword ptr [ebp - 4] // 83c424 | add esp, 0x24 // 8d44301a | lea eax, [eax + esi + 0x1a] // 6a1c | push 0x1c // 6a40 | push 0x40 // 894508 | mov dword ptr [ebp + 8], eax // ff15???????? | $sequence_3 = { 890d???????? ebdb 89848a00c0e7ff a1???????? ff05???????? } // n = 5, score = 200 // 890d???????? | // ebdb | jmp 0xffffffdd // 89848a00c0e7ff | mov dword ptr [edx + ecx*4 - 0x184000], eax // a1???????? | // ff05???????? | $sequence_4 = { e8???????? ff36 e8???????? 83c00c 68444e4549 } // n = 5, score = 200 // e8???????? | // ff36 | push dword ptr [esi] // e8???????? | // 83c00c | add eax, 0xc // 68444e4549 | push 0x49454e44 $sequence_5 = { 8d856cffffff c7856cffffff94000000 50 ff15???????? 6a05 } // n = 5, score = 200 // 8d856cffffff | lea eax, [ebp - 0x94] // c7856cffffff94000000 | mov dword ptr [ebp - 0x94], 0x94 // 50 | push eax // ff15???????? | // 6a05 | push 5 $sequence_6 = { c20800 55 8bec 81ec98000000 56 57 } // n = 6, score = 200 // c20800 | ret 8 // 55 | push ebp // 8bec | mov ebp, esp // 81ec98000000 | sub esp, 0x98 // 56 | push esi // 57 | push edi $sequence_7 = { 899d30ffffff 66895df0 f3ab 8d7df2 6a0f } // n = 5, score = 200 // 899d30ffffff | mov dword ptr [ebp - 0xd0], ebx // 66895df0 | mov word ptr [ebp - 0x10], bx // f3ab | rep stosd dword ptr es:[edi], eax // 8d7df2 | lea edi, [ebp - 0xe] // 6a0f | push 0xf $sequence_8 = { 83c00c 0107 8b37 03f3 e8???????? 6854414449 } // n = 6, score = 200 // 83c00c | add eax, 0xc // 0107 | add dword ptr [edi], eax // 8b37 | mov esi, dword ptr [edi] // 03f3 | add esi, ebx // e8???????? | // 6854414449 | push 0x49444154 $sequence_9 = { 57 c7460404100680 897e0c 894614 ff75f8 53 ff15???????? } // n = 7, score = 200 // 57 | push edi // c7460404100680 | mov dword ptr [esi + 4], 0x80061004 // 897e0c | mov dword ptr [esi + 0xc], edi // 894614 | mov dword ptr [esi + 0x14], eax // ff75f8 | push dword ptr [ebp - 8] // 53 | push ebx // ff15???????? | condition: 7 of them and filesize < 118784 }
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