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

Static analysis result for SHA-256 82c2fa42496f8a6c…

MALICIOUS

Office (OLE) / .XLS

54.0 KB Created: 2020-10-28 08:15:02 Authoring application: Microsoft Excel
MD5: cb990ee164f3b5a01f34d6f1d0d52475 SHA-1: 65176a14af2fd1ca52c3301f823d3d96fb65a17a SHA-256: 82c2fa42496f8a6ced13a58b5a9b7648c6a8553da1cfd419f6da9c8e6079414c
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1059.001 PowerShell T1566.001 Spearphishing Attachment

The file is an Excel 4.0 macro-enabled spreadsheet. Heuristics indicate the presence of an Auto_Open macro, which is a common technique for executing malicious code upon opening the document. The macro uses dangerous functions like RUN=0, suggesting it's designed to execute arbitrary commands. The presence of environment evasion techniques further supports malicious intent. The macro's primary function appears to be executing a second-stage payload, though the exact mechanism is obfuscated.

Heuristics 4

  • 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.
  • XLM Auto_Open environment-evasion HALT gate high OLE_XLM_ENVIRONMENT_EVASION_HALT
    Excel 4.0 macro sheet auto-executes multiple GET.WORKSPACE / GET.WINDOW environment checks and halts execution when the host does not match the expected user environment. This is a common sandbox-evasion pattern in XLM malware and is stronger than a bare XLM macro-sheet indicator.
  • 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
4e01c7d0783a3dde7abf23636ddd33d66de3b0e7ad813b05df195f7ebb66a57a		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 16006 bytes

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