can u analyze this PE binary? Is it malicious? what could it be?
Tool call: open_ghidra_server with args: {} succeeded
Assessing binary threat
I see the user's asking about whether a binary is malicious, so I need to approach this methodically. First, I'll gather high-level info, like lists of imports, exports, strings, entry points, and resources. Then, I’ll analyze for suspicious behavior, focusing on API calls that might indicate malware, such as registry access or network activity. I'll locate the entry point function and decompile it for closer examination. Finally, I’ll summarize my findings on the binary's behavior.
Tool call: list_imports with args: {"offset":0,"limit":100} succeeded
Tool call: list_namespaces with args: {"offset":0,"limit":100} succeeded
Tool call: list_methods with args: {} succeeded
Tool call: decompile_function_by_address with args: {"address":"entry"} succeeded
Tool call: decompile_function with args: {"name":"RenameAndEncryptFilesInDirectory"} succeeded
Tool call: decompile_function_by_address with args: {"address":"0x0600000C"} succeeded
Tool call: decompile_function_by_address with args: {"address":"entry"} succeeded
Analyzing binary functionality
The user is asking if a PE binary is malicious. Upon loading it in Ghidra, I see it's a .NET application with imports that point toward potential ransomware behavior. Functions like RenameFiles, EncryptFile, and others imply file renaming and encryption tasks. This suggests ransomware-like capabilities. It’s likely a .NET RAT or variant that may store files under a random password. I’ll need to look closely at the EncryptFile method to gather more details.
Tool call: decompile_function with args: {"name":"EncryptFile"} succeeded
Investigating file restoration options
I'm thinking about investigating options like DecryptFile or RestoreFiles to confirm they're reversible. I’ll want to gather details and outline the next steps: using ILSpy to inspect the managed code, examining resources for embedded keys, and checking out any network calls. Additionally, I should review the imports for System.IO and System.Security.Cryptography for further insights. Finally, I'll wrap things up with a concise summary.
The file you’ve dropped is not a native Win32 exe at all but a thin native stub (CorExeMain) that boots into the .NET CLR. All of the “meat” lives in managed code—Ghidra’s decompiler is just trying (and failing) to turn JIT-ted .NET code back into C.
From the list of methods:
• RenameFiles, RenameFilesInDirectory, RenameFile
• CopyAndRenameRftFiles
• GenerateRandomString, GenerateRandomPassword
• EncryptFile, DecryptFile
• RenameAndEncryptFilesInDirectory
• RestoreFiles, RestoreFilesInDirectory
• button1_Click, button2_Click, Timer_Tick, etc.
…and the fact that there are functions to
• walk a directory,
• rename files,
• generate random strings/passwords,
• encrypt (and later decrypt/restore) files,
this strongly smells like a simple file-encryption utility—or outright ransomware. GUI event handlers (button1_Click, button2_Click) imply a two-button WinForms app (probably “Encrypt” and “Decrypt” or “Start”/“Restore”).
At this level we see no network routines or phone-home code, so it may simply be a “DIY” file-encryptor rather than a fully-blown botnet client. But if you run it and point it at your documents folder it will almost certainly rename your files (to some new extension) and encrypt their contents with a random key.
Next steps:
- Grab a .NET decompiler (ILSpy, dnSpy, dotPeek) and load the EXE.
- Look at the bodies of EncryptFile and DecryptFile in IL to see which algorithm (AES? RC4?…) and how the key is derived/stored.
- Check for any hard-coded C2 URLs, SMTP addresses or embedded public keys.
- If you really just want to confirm whether it’s “safe,” run it in a sandbox (VM) on some dummy files and see exactly what it does.
Bottom line: this is almost certainly a file-encryption tool—very likely ransomware-style. Treat it as untrusted.