Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 3bfbb880816050ed…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-27 11:40:02 Authoring application: Microsoft Excel
MD5: d4a2a9deeea84bc623b60cf6ea8dacc7 SHA-1: adeeb9f92b4a08bbb9e0b984462239439debbff1 SHA-256: 3bfbb880816050ed7eaec64931393a0d9f2b97536fe4a6ec78c1d2cfdd918b8f
140 Risk Score

Malware Insights

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

The file is an Excel 4.0 macro-enabled workbook. Static analysis detected the presence of an Auto_Open defined name, which is a critical indicator of malicious intent as it allows for automatic execution of macros upon opening the document. The macro sheet contains dangerous formula APIs, specifically the RUN function, indicating it's designed to execute arbitrary code. The document body is heavily obfuscated and truncated, preventing a clear understanding of its specific lure, but the presence of the RUN function strongly suggests it's a downloader for a second-stage payload.

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
2720a029bb07be59224a0469f63b8c557fce22ba19d14d5052ab6e627aef066c
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6749 bytes