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

Static analysis result for SHA-256 a7f261c74ba04e91…

MALICIOUS

Office (OLE) / .XLS

46.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-06-09
MD5: a66062804fd99c71466ed3313dae7418 SHA-1: 2ecb59a0183c93a606c958b87f4e971dd345ead2 SHA-256: a7f261c74ba04e91f8215d3c1857935a7e4898564169cab7cb64d77b6f43b627
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: User Execution: Malicious File

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of Excel 4.0 macros designed to execute automatically upon opening. The Auto_Open function is configured to call dangerous formula APIs, specifically the RUN function, which is used to execute external commands. The extracted URLs are likely used to download and execute a second-stage payload, a common technique for initial access.

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
8530ce57f2115827ea23c5c95d01d856452a8f9ec319f9a971de39914dabeda2
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7802 bytes