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

Static analysis result for SHA-256 48ece4eca75461e0…

MALICIOUS

Office (OLE) / .XLS

36.0 KB Created: 2020-11-25 10:43:35 Authoring application: Microsoft Excel First seen: 2022-02-19
MD5: d2e6d7c277d582f26b9aff7e916a03e2 SHA-1: 622aaddf794f394f59dc9657d93ee84ce3b4fc6e SHA-256: 48ece4eca75461e0606fcb05270c8bdeeda538effb207fa7cbc999b4d7707136
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The sample is an Excel 4.0 macro sheet (XLM) that contains an Auto_Open defined name, indicating it will execute macros automatically upon opening. The critical heuristic firings confirm the presence of dangerous formula APIs, specifically the 'RUN' function, which is used to execute arbitrary commands. The document body contains heavily obfuscated and non-sensical text, likely to evade basic content analysis, further supporting a malicious intent.

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
efd311847b792c9ee2b72ba776634efc992cde69317b74ca7271227f48d1625e		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6406 bytes

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