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

Static analysis result for SHA-256 01b2979ee97551e8…

MALICIOUS

Office (OLE) / .XLS

88.8 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: b3c92170caa646682a35f4c338a922dd SHA-1: 696412d8f218233fcb6efb3e96a9a1680bc05043 SHA-256: 01b2979ee97551e890dd4ef0cd2261251158ff937da8ae23abb60ab1e217cdee
300 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1105 Ingress Tool Transfer

The file is a Microsoft Excel spreadsheet exhibiting multiple high-severity heuristics, including an OLE slack anomaly, an appended executable payload, and a critical finding for CVE-2009-3129, which is an Excel FEATHEADER record overflow vulnerability. Furthermore, a PE executable is embedded within the OLE structure. These indicators strongly suggest the file is designed to exploit this vulnerability to execute the embedded payload.

Heuristics 7

  • CVE-2009-3129 — Excel FEATHEADER record overflow critical CVE exact CVE_2009_3129
    Workbook BIFF stream contains a FEATHEADER (Feature Header) record with anomalous size (record_size=23, isf=2, cbHdrData=4294967295). Legitimate FEATHEADER records are tiny (<100 bytes) and carry cbHdrData values that fit in the record body; the value here is the documented CVE-2009-3129 exploit primitive — cbHdrData drives a memcpy with attacker-controlled size, leading to memory corruption and code execution in Excel 2007/2003.
  • Embedded PE executable critical OLE_EMBEDDED_EXE
    MZ/PE header found inside document — possible embedded executable
  • Reference to LoadLibrary API high SC_STR_LOADLIBRARY
    Reference to LoadLibrary API
  • Reference to GetProcAddress API high SC_STR_GETPROCADDRESS
    Reference to GetProcAddress API
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 90,884 bytes but its declared streams total only 24,565 bytes — 66,319 bytes (73%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
  • OLE file has appended executable-looking payload bytes high OLE_APPENDED_PAYLOAD
    OLE compound file contains a large high-entropy region beyond the declared major streams and that region includes shellcode, PE, or loader API markers. This is a payload-carrier signal, not a specific CVE attribution by itself.
  • Reference to VirtualAlloc API medium SC_STR_VIRTUALALLOC
    Reference to VirtualAlloc API

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
embedded_office_0000b000.exe
9c07635c84ca22ad80bf649c6e55d2861b61c6ca8cc8b0fad700dd11a487c26e		 embedded-pe Office MZ+PE at offset 0xB000 45828 bytes

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