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

Static analysis result for SHA-256 9e5f35b4b517bb36…

MALICIOUS

Office (OLE) / .XLS

54.5 KB Created: 2020-10-28 08:15:02 Authoring application: Microsoft Excel
MD5: bebfedc4d60c9a8f2f14eaa569877dc1 SHA-1: 17f769b3199b8ebf46ad4fb272545f7166bee426 SHA-256: 9e5f35b4b517bb36d45b9639fc1f3a84b455450337546b6d77e9f3339c13724a
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1564.002 Hidden Window T1027 Obfuscated Files or Information

The sample 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 critical heuristic 'OLE_XLM_DANGEROUS_FN' specifically flags the use of the 'RUN' function, indicating an attempt to execute external commands or payloads. The 'OLE_XLM_ENVIRONMENT_EVASION_HALT' heuristic suggests the macro attempts to evade analysis. The macro sheet itself contains obfuscated data, further supporting a malicious intent.

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
7760fc9a4fb2a4da7eba73e576eb793bcac3dea2e73eafcb1bc49a174b43f3ca		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 16474 bytes

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