Malicious Office (OLE) / .XLS — malware analysis report

Static analysis result for SHA-256 9bf829aface4bf62…

MALICIOUS

Office (OLE) / .XLS

229.0 KB Created: 2020-09-20 21:17:44
MD5: 54d2296f29a7d7dbc0c3435128d275e4 SHA-1: 2e53b1859442212a63a2560052ed29c38b18b468 SHA-256: 9bf829aface4bf627257e572de407d1074f65c2c04b64f2fe1c9e7ae6a1f43b9
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 PowerShell T1059.001 PowerShell T1204.002 Malicious File

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of an Excel 4.0 macro sheet with an Auto_Open entry that uses dangerous functions. The extracted macro script reveals that it constructs and executes a PowerShell command. This command is designed to download a file named 'gg.exe' from the URL 'https://tinyurl.com/8z8setqa', execute it, and then move it to the user's AppData directory, likely establishing persistence via a Run key. The script's obfuscation and use of concatenation to build the command and URL are noted.

Heuristics 3

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
d50b5f9397c64fc87e7acbb27ec9f79075b566716fe2b5c67b8a0f60519382e4
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1387 bytes