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

Static analysis result for SHA-256 16d9d2a45dae8a24…

MALICIOUS

Office (OLE) / .XLSX

43.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 5b0ad7cba62fb1932a60699693fdcc9a SHA-1: e0122d4717a6026b21df630b3a70be8d5944cad8 SHA-256: 16d9d2a45dae8a247713c79244796b9dcfde02ffadaaac4681daab8fa657fda4
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.005 Visual Basic T1204.002 Malicious File T1071.001 Web Protocols

The sample is an Excel file containing Excel 4.0 macros, indicated by the OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN heuristics. The macro is designed to execute a command that includes 'rundll32.exe DllRegisterServer' and a URL, 'http://aosolucion.com/uqiyr/', likely to download and execute a second-stage payload. The presence of a SE_ENABLE_LURE heuristic suggests the document prompts the user to enable macros.

Heuristics 5

  • 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.
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • 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.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
b68def77bf3d78b7c0be9f30ad60574365101f4a762f9255957bf746dbc07ff7		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1729 bytes

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