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

Static analysis result for SHA-256 1177558cacb8f285…

MALICIOUS

Office (OLE) / .XLS

41.0 KB Created: 2015-06-05 18:17:20 Authoring application: Microsoft Excel
MD5: a19fec796c12cd04e62dc8fe120fe111 SHA-1: 07125c595db786b698e19aac4c6f40038102fbf0 SHA-256: 1177558cacb8f285e47d86d25b183b926ca3a39640a0eea8a58e11a5e207226a
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known method for executing malicious code upon opening the workbook. The heuristics indicate the use of dangerous formula APIs, including RUN, suggesting the macro attempts to execute external commands. The macro sheet itself is heavily obfuscated, but the presence of Auto_Open and the use of RUN point towards a downloader or initial execution stage.

Heuristics 3

  • 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.
  • 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
ffe630d343c90c6d44e1d4aff563472b7466d2f7cbdd61ddb92f764406bc61bf
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8005 bytes