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

Static analysis result for SHA-256 1f65f4c1b45b2d09…

MALICIOUS

Office (OLE) / .XLS

54.5 KB Created: 2020-10-28 08:15:02 Authoring application: Microsoft Excel
MD5: 777719ca4ea351104a55b1c78c1e4739 SHA-1: 4e23b00e3213f43734bcaaed050b7f0d7d97d8de SHA-256: 1f65f4c1b45b2d09425f04c4788b30fbba7af2b5c7a4ba21cc80640361394f8a
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic 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 sheet contains numerous obfuscated strings and a defined name for Auto_Open, suggesting an attempt to hide its functionality. The presence of environment evasion techniques further supports malicious intent. The macro is likely designed to download and execute a second-stage payload.

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
ec87bbe06fda29cdc82b027ea17d0f682c3f4107ef94f55f3caadffcadb9eb54		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 16466 bytes

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