Case op19 ·
evaluated model gemma431Bit ·
judges ClaudeAI, GeminiAI, OpenAI
Selection reason: disagreement_census
Understanding point
check the amount of system memory
Code snippet · op19/code_clean1.txt
__int64 sub_14007479E()
{
__int64 result; // rax
int v1; // ecx
int i; // r8d
BOOL v3; // [rsp+2Ch] [rbp-4Ch]
struct _STRUCT Buffer; // [rsp+30h] [rbp-48h] BYREF
Buffer.field0 = 64;
v3 = GlobalMemoryStatusEx(&Buffer);
result = 4105884444LL;
v1 = 592532183;
if ( !(Buffer.field1 >> 31) )
v1 = -189082852;
for ( i = -1487193492; ; i = v1 )
{
while ( 1 )
{
while ( i <= -118447998 )
{
if ( i == -1960191909 )
{
i = 929412080;
result = 1;
}
else if ( i == -1487193492 )
{
i = 1526186595;
if ( !v3 )
i = -1960191909;
}
else
{
i = -118447997;
result = 0;
}
}
if ( i > 929412079 )
break;
if ( i == -118447997 )
{
i = 929412080;
}
else
{
i = -118447997;
result = 1;
}
}
if ( i == 929412080 )
break;
}
return result;
}
Evaluated model output (what the LLM said about the code) · op19/result_gemma431Bit1.txt
### 1. Functionality Description
The provided code is a heavily obfuscated function designed to perform a basic system environment check.
**Simplified Logic:**
The function calls the Windows API `GlobalMemoryStatusEx` to retrieve information about the system's physical and virtual memory.
- If `GlobalMemoryStatusEx` **fails** (returns `FALSE`), the function eventually returns **1**.
- If `GlobalMemoryStatusEx` **succeeds** (returns `TRUE`), the function eventually returns **0**.
The primary purpose of this function is to detect whether the malware is running in an environment (such as a sandbox, emulator, or debugger) where standard Windows API calls are either not implemented correctly or are being hooked/interfered with.
---
### 2. Well-Known Algorithms
No standard cryptographic or data-processing algorithms are used. However, the code employs a well-known **obfuscation pattern** called **Control Flow Flattening**.
Instead of using standard `if/else` or `while` blocks to dictate logic, the program uses a "dispatcher" (the `for` and `while` loops) and a state variable (`i`) to jump between blocks of code. This is a common feature of obfuscators like **OLLVM (Obfuscator-LLVM)**.
---
### 3. Indicators of Compromise (IOCs)
No traditional network or file-based IOCs were found in this snippet.
- **File Paths:** None
- **IP Addresses / Domains:** None
- **Registry Keys:** None
- **Commands/Scripts:** None
- **API Calls:** `GlobalMemoryStatusEx` (Used for environment fingerprinting).
---
### 4. MITRE ATT&CK Mapping
| Technique ID | Technique Name | Justification |
| :--- | :--- | :--- |
| **T1497** | Virtualization/Sandbox Evasion | The code calls `GlobalMemoryStatusEx` and checks the return value. Malware often does this because some sandboxes fail to emulate this API correctly or return inconsistent values, allowing the malware to detect the analysis environment and terminate or change behavior. |
---
### 5. Obfuscation and Evasion Techniques
The code utilizes several techniques to hinder reverse engineering:
* **Control Flow Flattening:** The logic is broken into a state machine. The actual execution path is hidden behind a series of `while` loops and `if/else` checks using large, arbitrary integer constants (e.g., `-1487193492`, `929412080`) to determine the next block to execute.
* **Opaque Predicates / Junk Logic:** The check `if ( !(Buffer.field1 >> 31) )` is largely meaningless. `Buffer.field1` (which corresponds to `dwMemoryLoad` in the `MEMORYSTATUSEX` struct) is a percentage (0-100). Shifting it right by 31 bits will always result in 0. This is used to create a fake conditional branch to confuse analysts.
* **Dead Store/Constant Noise:** The variable `result` is initialized to `4105884444LL`, a value that is immediately overwritten, serving only to distract the analyst.
---
### 6. Observed Facts vs. Inferred Behavior
#### Observed Facts (Directly from code)
- The function calls `GlobalMemoryStatusEx` with a buffer size of 64 bytes.
- The function uses a state variable `i` to navigate a complex set of nested loops.
- The function returns either `0` or `1` based on the result of the API call and the subsequent state transitions.
- The code uses large signed integers to control the flow of execution.
#### Inferred Behavior (Reasoning)
- **Inference:** The function is an anti-analysis check.
- **Reasoning:** The use of `GlobalMemoryStatusEx` combined with extreme control flow obfuscation is characteristic of malware attempting to hide its true intent from automated analysis tools.
- **Inference:** The code was likely generated by an automated obfuscator (like OLLVM).
- **Reasoning:** The specific pattern of a "dispatcher" loop using large constants to manage state is the signature of Control Flow Flattening.
{
"understanding_point": "check the amount of system memory",
"full_evaluation": "The understanding point is that the code checks the amount of system memory. The summary clearly states that the function calls GlobalMemoryStatusEx to retrieve information about the system's physical and virtual memory. It explicitly discusses the dwMemoryLoad field (a memory percentage value) within the MEMORYSTATUSEX struct and mentions the check on Buffer.field1. The summary describes retrieving memory status and inspecting memory-related fields, which conveys that the code is checking the amount of system memory. This is a clear and direct match to the understanding point.",
"explanation": "The summary explicitly states the function calls GlobalMemoryStatusEx to retrieve physical and virtual memory information and discusses the memory load field, clearly conveying a check of system memory.",
"evidence": "The function calls the Windows API `GlobalMemoryStatusEx` to retrieve information about the system's physical and virtual memory.",
"support_strength": 3,
"satisfied": "true"
}
{
"understanding_point": "check the amount of system memory",
"full_evaluation": "The candidate summary explicitly states that the function calls the Windows API `GlobalMemoryStatusEx` \"to retrieve information about the system's physical and virtual memory.\" Retrieving information about physical and virtual memory directly equates to checking the amount of system memory. The summary also mentions that `Buffer.field1` corresponds to `dwMemoryLoad` in the `MEMORYSTATUSEX` struct, which is a percentage (0-100), further confirming that memory usage/amount is being checked. The purpose of this check (anti-analysis) is also explained, but the core action of checking memory amount is clearly described.",
"explanation": "The summary explicitly states that the function calls `GlobalMemoryStatusEx` to retrieve information about the system's physical and virtual memory, which directly implies checking the amount of system memory.",
"evidence": "The function calls the Windows API `GlobalMemoryStatusEx` to retrieve information about the system's physical and virtual memory.",
"support_strength": 3,
"satisfied": "true"
}
{
"understanding_point": "check the amount of system memory",
"full_evaluation": "The candidate summary clearly discusses system memory in the general sense, stating that the code calls GlobalMemoryStatusEx to retrieve information about physical and virtual memory. However, the specific understanding point is that the code checks the amount of system memory. The summary does not clearly state that the amount of memory is examined, compared, or used as a decision criterion. In fact, it repeatedly characterizes the simplified logic as checking only whether GlobalMemoryStatusEx succeeds or fails, and returning based on the API call's return value. This is weaker than, and potentially contrary to, the claim that the code checks the amount of system memory. The mention of memory information is related, but it does not commit to the specific factual content that the amount of system memory is checked.",
"explanation": "The summary mentions retrieving physical and virtual memory information via GlobalMemoryStatusEx, but it does not clearly say the code checks the amount of system memory. Instead, it says the function bases its result on whether the API call succeeds or fails.",
"evidence": "The function calls the Windows API `GlobalMemoryStatusEx` to retrieve information about the system's physical and virtual memory.",
"support_strength": 1,
"satisfied": "false"
}