Code snippet · op06/code_clean1.txt
__int64 __fastcall sub_180008BE0(__int64 a1, __int64 a2) {
v153 = &dword_9688;
v53 = &dword_9688;
var01 = 0xC9DA0;
iv = byte_968C;
var02 = &unk_969C;
v154 = sub_02;
v76 = (BYTE *)sub_02;
v75 = &unk_B78 - (_UNKNOWN *)sub_02;
sub_01((BYTE *)sub_02);
sub_02(&n36200);
sub_01(v76);
v23 = n36200;
for ( i = 3; ; ++i )
{
v42 = i - 1;
v10 = 0;
for ( j = 3; j < v42; ++j )
{
if ( !(i % j) )
{
if ( v10 == 2 )
{
v10 = 3;
break;
}
*(&var08 + v10++) = j;
}
}
if ( v10 != 2 )
continue;
v12 = var08;
if ( var08 >= 2 )
{
if ( v12 == 2 )
{
v3 = 1;
}
else if ( v12 % 2 )
{
for ( k = 3; k * k <= v12; k += 2 )
{
if ( !(v12 % k) )
{
v3 = 0;
goto LABEL_36;
}
}
v3 = 1;
}
else
{
v3 = 0;
}
}
else
{
v3 = 0;
}
LABEL_36:
if ( !v3 )
continue;
v14 = var09;
if ( var09 >= 2 )
{
if ( v14 == 2 )
{
v4 = 1;
}
else if ( v14 % 2 )
{
for ( m = 3; m * m <= v14; m += 2 )
{
if ( !(v14 % m) )
{
v4 = 0;
goto LABEL_49;
}
}
v4 = 1;
}
else
{
v4 = 0;
}
}
else
{
v4 = 0;
}
LABEL_49:
if ( !v4 )
continue;
if ( !v23 )
break;
--v23;
}
v135[0] = i;
v135[1] = var08;
v135[2] = var09;
qmemcpy(v203, v135, sizeof(v203));
qmemcpy(v204, v203, sizeof(v204));
qmemcpy(var03, v204, 0xCu);
size = 12;
bTrue_1 = dword_0x10f & 4;
if ( (dword_0x10f & 4) != 0 )
{
v155 = var10;
v78 = (BYTE *)var10;
v77 = &unk_BC8 - (_UNKNOWN *)var10;
sub_01((BYTE *)var10);
var10(n345600);
sub_01(v78);
v156 = var_0aa;
v80 = (BYTE *)var_0a;
v79 = (char *)sub_C18 - (char *)var_0aa;
sub_01((BYTE *)var_0aa);
var_0aa(n311015);
sub_01(v80);
v157 = sub_10;
v82 = (BYTE *)sub_10;
v81 = &unk_72D4 - (_UNKNOWN *)sub_10;
sub_01((BYTE *)sub_10);
sub_11 = sub_10();
sub_01(v82);
((void (__fastcall *)(_QWORD *))sub_11)(v83);
pThread[1] = 116444736000000000LL;
v39 = v83[0] - 116444736000000000LL;
v54 = (v83[0] - 116444736000000000LL) / 10000000uLL - n311015[0];
n311015[1] = n345600[0];
v177[0] = v54 / n345600[0];
size = 20;
}
var06 = 0;
if ( (dword_0x10f & 1) != 0 )
{
n311015[2] = sub_0b;
v84 = (BYTE *)sub_0b;
v83[1] = &unk_73E4 - (_UNKNOWN *)sub_0b;
sub_01((BYTE *)sub_0b);
sub_0b1 = sub_0b();
sub_01(v84);
((void (__fastcall *)(_QWORD, _BYTE *, __int64))sub_0b1)(0, var_0b1, 260);
filename = var_0b1;
for ( n = var_0b1; *(_WORD *)n; n += 2 )
{
if ( *(_WORD *)n == '\\' || *(_WORD *)n == '/' )
filename = n + 2;
}
v161 = sub_0b2;
v86 = (BYTE *)sub_0b2;
v85 = &unk_74C4 - (_UNKNOWN *)sub_0b2;
sub_01((BYTE *)sub_0b2);
sub_0b4 = (void (__fastcall *)(BYTE *))sub_0b2();
sub_01(v86);
sub_0b4(filename);
v163 = sub_0b3;
v88 = (BYTE *)sub_0b3;
v87 = &unk_75A4 - (_UNKNOWN *)sub_0b3;
sub_01((BYTE *)sub_0b3);
lstrlenW = (__int64 (__fastcall *)(BYTE *))sub_0b3();
sub_01(v88);
var06 = 2 * lstrlenW(filename);
size += var06;
}
lastArg = 0;
lastArgLen = 0;
if ( (dword_0x10f & 2) != 0 )
{
v165 = sub_0b5;
v90 = (BYTE *)sub_0b5;
v89 = &unk_76A8 - (_UNKNOWN *)sub_0b5;
sub_01((BYTE *)sub_0b5);
GetCommandLineW = (__int64 (*)(void))sub_0b5();
sub_01(v90);
cmdLineW = GetCommandLineW();
v167 = sub_0b6;
v92 = (BYTE *)sub_0b6;
v91 = &unk_77B4 - (_UNKNOWN *)sub_0b6;
sub_01((BYTE *)sub_0b6);
sub_0b7 = (__int64 (__fastcall *)(__int64, int *))sub_0b6();
sub_01(v92);
argvW = (BYTE **)sub_0b7(cmdLineW, &argc);
if ( argc > 0 )
{
n345600[1] = argc - 1;
lastArg = argvW[argc - 1];
v171 = sub_0b3;
v94 = (BYTE *)sub_0b3;
v93 = &unk_75A4 - (_UNKNOWN *)sub_0b3;
sub_01((BYTE *)sub_0b3);
sub_0b8 = (__int64 (__fastcall *)(BYTE *))sub_0b3();
sub_01(v94);
lastArgLen = 2 * sub_0b8(lastArg);
size += lastArgLen;
}
}
*(_DWORD *)v25 = 0;
v173 = var_0b9;
v96 = (BYTE *)var_0b9;
v95 = &unk_B28 - (_UNKNOWN *)var_0b9;
sub_01((BYTE *)var_0b9);
var_0b9(v25);
sub_01(v96);
v174 = sub_0b9;
v98 = (BYTE *)sub_0b9;
v97 = &unk_4BC4 - (_UNKNOWN *)sub_0b9;
sub_01((BYTE *)sub_0b9);
LOBYTE(v2) = sub_0b9(v25[0]);
var_0b10 = v2;
sub_01(v98);
if ( var_0b10 )
size += 4;
v175 = lib_memcpy;
v100 = (BYTE *)lib_memcpy;
v99 = &unk_6F54 - (_UNKNOWN *)lib_memcpy;
sub_01((BYTE *)lib_memcpy);
lib_memcpy(var04, var03, 0xCu);
sub_01(v100);
var05 = 12;
if ( bTrue_1 )
{
v176 = lib_memcpy;
v102 = (BYTE *)lib_memcpy;
v101 = &unk_6F54 - (_UNKNOWN *)lib_memcpy;
sub_01((BYTE *)lib_memcpy);
lib_memcpy(time_result_qword, (BYTE *)v177, 8u);
sub_01(v102);
var05 = 20;
}
v177[1] = lib_memcpy;
v104 = (BYTE *)lib_memcpy;
v103 = &unk_6F54 - (_UNKNOWN *)lib_memcpy;
sub_01((BYTE *)lib_memcpy);
lib_memcpy(&var04[var05], filename, var06);
sub_01(v104);
v6 = var06 + var05;
v177[2] = lib_memcpy;
v106 = (BYTE *)lib_memcpy;
v105 = &unk_6F54 - (_UNKNOWN *)lib_memcpy;
sub_01((BYTE *)lib_memcpy);
lib_memcpy(&var04[v6], lastArg, lastArgLen);
sub_01(v106);
v177[3] = var_0b11;
v108 = (BYTE *)var_0b11;
v107 = &unk_35BC - (_UNKNOWN *)var_0b11;
sub_01((BYTE *)var_0b11);
v27 = var_0b11(var04, size, var_0b12);
sub_01(v108);
if ( v27 )
return v27;
v177[4] = sub_0b12;
v110 = (BYTE *)sub_0b12;
v109 = &unk_44F0 - (_UNKNOWN *)sub_0b12;
sub_01((BYTE *)sub_0b12);
v28 = sub_0b12(var_0b12, iv, var02, var01, 64, &var_0b13, &a7);
sub_01(v110);
}
Evaluated model output (what the LLM said about the code) · op06/result_GeminiAI1.txt
The provided code snippet is a subroutine that performs several preparatory steps before a critical final operation, highly suggestive of decrypting an embedded payload or configuration data. It combines mathematical calculations, system information gathering, and obfuscation techniques to achieve its goal.
---
### 1. Functionality Description
The subroutine `sub_180008BE0` orchestrates the following sequence of actions:
1. **Cryptographic Context Initialization:** It initializes several variables (`var01`, `iv`, `var02`), where `iv` strongly suggests an Initialization Vector, and `var01`, `var02` likely represent sizes/lengths and data buffers, respectively, for a cryptographic operation.
2. **Prime Factor Search:** The code enters a `for` loop that searches for an integer `i` which possesses exactly two prime factors, stored in `var08` and `var09`. This involves a basic trial division algorithm to test for primality. These identified numbers (`i`, `var08`, `var09`) are then stored in `var03`.
3. **Dynamic API Resolution:** Throughout the function, calls to Windows API functions are not direct. Instead, they are resolved via an indirect mechanism involving `sub_01`. The pattern is `sub_01(function_pointer); function_pointer(arguments); sub_01(function_pointer_again);`. This is a common obfuscation technique.
4. **Conditional System Information Gathering:** The malware checks specific bits in a global flag `dword_0x10f` to determine which system information to collect:
* **System Timestamp and Timing (`dword_0x10f & 4`):** Retrieves the system time (likely `GetSystemTimeAsFileTime`), converts it to a different time format (e.g., Unix-like timestamp relative to 1970 epoch) by subtracting a specific `FILETIME` constant, and performs further time-related calculations.
* **Process Filename (`dword_0x10f & 1`):** Retrieves the full path of the current executable (likely `GetModuleFileNameW`) and then extracts only the base filename (e.g., "malware.exe" from "C:\Path\malware.exe").
* **Command Line Arguments (`dword_0x10f & 2`):** Retrieves the complete command line string (likely `GetCommandLineW`), parses it into individual arguments (likely `CommandLineToArgvW`), and specifically extracts the *last* argument provided.
5. **Data Aggregation and Key Derivation:** All the collected information – the prime-related values (`i`, `var08`, `var09`), optionally the calculated time value, the process filename, and the last command-line argument – are sequentially copied into a single buffer (`var04`). This aggregated buffer is then passed to `var_0b11`, which likely functions as a Key Derivation Function (KDF) or a hashing algorithm, producing a derived key or seed (`var_0b12`) based on the unique execution context.
6. **Cryptographic Operation:** Finally, the function calls `sub_0b12` with the derived key (`var_0b12`), the `iv`, `var02` (likely the data to be processed), `var01` (likely the size of the data), and other parameters (e.g., `64`, `&var_0b13`, `&a7`). This strongly suggests a symmetric cryptographic operation, most likely decryption of an embedded payload or configuration data.
---
### 2. Well-Known Algorithms
1. **Primality Testing / Prime Factor Search (Observed Fact):** The code explicitly implements a trial division algorithm to check for prime numbers and find two prime factors for a given integer `i`. This is a fundamental mathematical concept often associated with public-key cryptography (e.g., RSA key generation, which requires large prime numbers `p` and `q`).
2. **Symmetric Encryption/Decryption (Strongly Inferred):** The final call to `sub_0b12` with an Initialization Vector (`iv`), a derived key (`var_0b12`), and input/output buffers strongly indicates the use of a symmetric cipher. The argument `64` could represent a key size (e.g., 64-bit DES) or a block size for a block cipher.
---
### 3. Indicators of Compromise (IOCs)
Based on the provided snippet, there are no hardcoded, static IOCs such as specific IP addresses, domains, or registry keys. However, the code actively retrieves contextual information that would be crucial for dynamic IOCs:
* **File Paths (Inferred):** The base filename of the executing process is extracted. If the malware expects a specific name or renames itself, this could become an IOC.
* **Commands or Scripts (Inferred):** The last command-line argument is parsed. The content of this argument could be a critical IOC, containing C2 addresses, encrypted payloads, or specific commands.
---
### 4. MITRE ATT&CK Techniques
1. **T1036.004: Masquerading: Impersonate Command Line Utility**
* **Justification:** The code explicitly retrieves the entire command line and parses it to extract individual arguments, specifically focusing on the last argument. This is a common method for malware to receive dynamic instructions, configuration, or payloads from its launcher or C2.
* **Evidence:**
```c
GetCommandLineW = (__int64 (*)(void))sub_0b5(); // Resolves GetCommandLineW
cmdLineW = GetCommandLineW(); // Gets the command line string
sub_0b7 = (__int64 (__fastcall *)(__int64, int *))sub_0b6(); // Resolves CommandLineToArgvW
argvW = (BYTE **)sub_0b7(cmdLineW, &argc); // Parses into arguments
if ( argc > 0 ) { lastArg = argvW[argc - 1]; /* ... */ } // Extracts last argument
```
2. **T1082: System Information Discovery**
* **Justification:** The code gathers specific details about the execution environment, including the process filename and timing information. This is used by malware for self-awareness, unique identification, or as input for further operations.
* **Evidence:**
* **Process Filename:**
```c
((void (__fastcall *)(_QWORD, _BYTE *, __int64))sub_0b1)(0, var_0b1, 260); // Inferred GetModuleFileNameW
filename = var_0b1; // Stores process path, then extracts base filename
```
* **System Time/Timing:**
```c
sub_11 = sub_10(); // Inferred GetSystemTimeAsFileTime or similar
((void (__fastcall *)(_QWORD *))sub_11)(v83); // Calls to get system time
// ... calculations involving 116444736000000000LL (FILETIME epoch)
```
3. **T1480.001: Execution Guardrails: Environmental Keying**
* **Justification:** The malware collects multiple pieces of system and execution-specific data (prime factors, time-based values, filename, last command-line argument). This aggregated data is then used as input for `var_0b11`, which serves as a Key Derivation Function, generating a unique cryptographic key (`var_0b12`) dependent on the specific environment. This technique makes payload decryption difficult without replicating the exact execution context.
* **Evidence:**
```c
// i, var08, var09 (prime factors)
// v177[0] (calculated time)
// filename (process name)
// lastArg (command line argument)
// ... all combined into var04 ...
v27 = var_0b11(var04, size, var_0b12); // KDF using aggregated data
v28 = sub_0b12(var_0b12, iv, var02, var01, 64, &var_0b13, &a7); // Cryptographic op with derived key
```
4. **T1027: Obfuscated Files or Information**
* **Justification:** The extensive use of `sub_01` to wrap and dynamically resolve API calls is a direct method of obfuscating the code. It complicates static analysis by hiding direct imports and makes it harder for signature-based detection mechanisms to identify specific API usage patterns.
* **Evidence:** Repeated pattern:
```c
v154 = sub_02;
sub_01((BYTE *)sub_02); // Obfuscation/resolution call
sub_02(&n36200); // Actual function call
sub_01(v76); // Another obfuscation/resolution call
```
---
### 5. Obfuscation or Evasion Techniques
1. **Dynamic API Resolution / Indirect Function Calls (Observed Fact):** The most prominent obfuscation is the consistent pattern of `sub_01` calls surrounding indirect function calls. `sub_01` likely acts as a dynamic resolver (e.g., using `LoadLibrary`/`GetProcAddress` internally) or a mechanism to modify/unhook function pointers at runtime. This complicates static analysis and makes it difficult to directly identify API usage.
2. **Environmental Keying (Inferred Behavior):** The derivation of the cryptographic key (`var_0b12`) from various system and execution-specific attributes (prime factors, time, process name, command-line arguments) is a form of environmental keying. This technique ties the decryption key to the specific environment, hindering generic decryption attempts and making analysis more complex as the key changes per victim or execution.
3. **Arithmetic Obfuscation / Complexity (Inferred Behavior):** The initial prime factor search, while potentially contributing to key derivation, also adds computational complexity and an unusual pattern to the code, which could be intended to slow down analysis or make automatic signature generation harder.
4. **Conditional Code Flow (Observed Fact):** The use of `dword_0x10f` as a flag to enable/disable different information gathering modules (`& 4`, `& 1`, `& 2`) introduces conditional execution paths. Without knowing the runtime value of `dword_0x10f`, a full understanding of the information gathered is not possible via static analysis alone.
---
### 6. Distinction Between Observed Facts and Inferred Behavior
**Observed Facts (Directly from code):**
* Initialization of variables `var01`, `iv`, `var02`, `dword_9688`, `byte_968C`, `unk_969C`.
* A loop performing mathematical operations (`%`, `*`, `<=`, `+=`) to find `i`, `var08`, `var09`, and checking their primality.
* Calls to `sub_01` before and after numerous indirect function calls.
* The presence of `dword_0x10f` controlling conditional blocks.
* Retrieval of wide-character strings and extraction of substrings (e.g., `filename`).
* Usage of `lstrlenW` (resolved via `sub_0b3`) for length calculations.
* Calls to `GetCommandLineW` and `CommandLineToArgvW` (resolved dynamically).
* The constant `116444736000000000LL` in time calculations, typical for `FILETIME` conversions.
* Data copying using `qmemcpy`/`lib_memcpy`.
* Final calls to `var_0b11` and `sub_0b12` with specific sets of arguments including `iv`, `var02`, `var01`.
**Inferred Behavior (Reasoning and Interpretation):**
* `sub_01` is a dynamic API resolution or obfuscation routine.
* The prime factor search is related to cryptographic key component generation, likely for unique keying.
* The `iv` variable suggests a symmetric block cipher operation.
* The time calculations likely involve `GetSystemTimeAsFileTime` and are used for anti-analysis or unique system identification.
* The filename acquisition uses `GetModuleFileNameW`.
* `var_0b11` is a Key Derivation Function (KDF) or a hashing algorithm that creates a unique key from gathered system data.
* `sub_0b12` is a symmetric decryption (or encryption) function, processing data (from `var02`) using the derived key (`var_0b12`).
* The overall purpose of the subroutine is to dynamically generate a key and decrypt an embedded payload or configuration data based on the execution environment.
GeminiAI judge verdict: not_satisfiedop06/judge_GeminiAI_GeminiAI_up1_1.txt
{
"understanding_point": "calculating odd semiprime and its factors for AES-CBC",
"full_evaluation": "The candidate summary describes a \"Prime Factor Search\" where \"The code enters a for loop that searches for an integer i which possesses exactly two prime factors, stored in var08 and var09.\" This clearly indicates the calculation of a semiprime and its factors. However, the summary does not specify that this semiprime must be \"odd\", which is a non-trivial omission from the first part of the understanding point.\n\nRegarding the second part, \"for AES-CBC\", the summary states that the operation \"strongly suggests a symmetric cryptographic operation\" and mentions an \"Initialization Vector (iv)\". It also notes that \"The argument 64 could represent a key size (e.g., 64-bit DES) or a block size for a block cipher.\" While the presence of an IV is consistent with CBC mode, the summary does not explicitly name \"AES\" or \"CBC\". Furthermore, suggesting \"64-bit DES\" as a possibility for the key/block size indicates that the specific algorithm is not identified as AES, which uses 128, 192, or 256-bit keys. Therefore, the specific algorithm \"AES-CBC\" is not clearly stated or implied; the summary only infers a generic symmetric block cipher with an IV. This part of the understanding point is related but insufficient.\n\nSince both parts of the understanding point are either partially expressed or related but insufficient, the entire understanding point is not clearly stated or implied.",
"explanation": "The summary describes finding a semiprime and its factors but omits the 'odd' qualifier. Crucially, it infers a generic symmetric cryptographic operation with an IV, but does not specify 'AES-CBC' and even suggests 'DES' as a possibility, making the link to AES-CBC insufficient.",
"evidence": "The code enters a for loop that searches for an integer i which possesses exactly two prime factors, stored in var08 and var09.\nThis strongly suggests a symmetric cryptographic operation, most likely decryption of an embedded payload or configuration data.\nThe argument 64 could represent a key size (e.g., 64-bit DES) or a block size for a block cipher.",
"support_strength": 1,
"satisfied": "false"
}