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

Static analysis result for SHA-256 327bae1c83108bf9…

MALICIOUS

Office (OLE) / .XLS

64.0 KB Created: 2010-04-29 03:03:45 Authoring application: Microsoft Excel
MD5: 1ec9c45ef3563ace6520522801a0bb82 SHA-1: c0a5566246058974ddc72344cd97dd7b3eeeba18 SHA-256: 327bae1c83108bf9192e07bf51f1f43034777f2c3b61c4d80f5abdb156f66089
200 Risk Score

Malware Insights

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

The file is an Excel 4.0 macro-enabled spreadsheet. Critical heuristics indicate the presence of an Auto_Open macro that utilizes dangerous functions, specifically 'RUN'. This suggests the macro is designed to execute arbitrary commands upon opening the document. The 'DOC BODY' contains what appears to be Vietnamese tax-related information, likely a lure to trick users into opening the malicious file. The presence of 'Auto_Open' and 'RUN' functions are the primary IOCs.

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.
  • Legacy Excel formula macro virus marker critical OLE_XLS_FORMULA_MACRO_VIRUS
    Workbook stream contains self-identifying legacy Excel formula macro virus markers. This indicates the document carries formula macro virus content even when no VBA project or modern XLM macro-sheet structure is present.
  • 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
1142117e9087a3839fc82745f4fb81e5f9397e0123e1bb5a00bcc358cde528d1		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 27258 bytes

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