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

Static analysis result for SHA-256 16a4582eb6a91ba2…

MALICIOUS

Office (OLE) / .XLS

54.0 KB Created: 2020-10-28 08:15:02 Authoring application: Microsoft Excel
MD5: 8e902d60f3a1d5d74d3e72dfd9abc7da SHA-1: 0f5502ed17b0f49f5ef67d6cba40156f0831ede3 SHA-256: 16a4582eb6a91ba24b10c7cfff4b58ed9642495072344d0eb5b907ce9388bfcf
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an Excel file containing Excel 4.0 macros, specifically an Auto_Open macro. This macro is configured to execute dangerous functions, including the RUN function, indicating an intent to run external code. The presence of environment evasion techniques suggests the macro attempts to avoid detection before execution. The macro sheet itself contains obfuscated strings and references to potentially dangerous functions, consistent with a downloader or initial execution stage.

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
a5e795b63e1856f70249850cda4af31a8861a3ed7d0f23434de83eb2e94a53e8		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 15935 bytes

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