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

Static analysis result for SHA-256 bae3fdaad02bdad5…

MALICIOUS

Office (OLE) / .XLS

70.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-06-03
MD5: 5c4a5a282b645e072c60459f4fc4c675 SHA-1: 2b61266a9640e220c379da6180ce723ffa90d354 SHA-256: bae3fdaad02bdad5fbbb62d0e2358cb6dcd77eb97fe2e750e69b8c7608e5f09b
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Service Execution T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell

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 like RUN. The extracted URLs are likely used to download and execute a second-stage payload. The macro sheet's Auto_Open function is designed to execute automatically when the workbook is opened, facilitating the initial infection vector.

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
b2124f09a0fec7faeef42f88c68da164b6a9b84efed16f528c7ac11c7695b4b9
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7646 bytes