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

Static analysis result for SHA-256 3e39abf37e1eaf1a…

MALICIOUS

Office (OLE) / .XLS

140.8 KB
MD5: c53c8b91a5bb45962350f6802d0b7d48 SHA-1: 1c8be7205c9f3bb199dca582db8b24912b82c602 SHA-256: 3e39abf37e1eaf1a4b13175dcfec23410ccbebbade3c6f06c82d9227da140ade
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1566.002 Spearphishing Attachment T1105 Ingress Tool Transfer

This XLS file is malicious due to the presence of an embedded PE executable. The heuristics indicate the use of Windows API functions like VirtualAlloc, LoadLibrary, and GetProcAddress, which are commonly used by malware to load and execute payloads. The large slack space in the OLE structure is also suspicious. The embedded executable is the primary IOC.

Heuristics 6

  • 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 144,132 bytes but its declared streams total only 56,346 bytes — 87,786 bytes (61%) 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).
  • Reference to VirtualAlloc API medium SC_STR_VIRTUALALLOC
    Reference to VirtualAlloc API
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://www.microsoft.com
    • https://www.verisign.com/rpa
    • http://ocsp.verisign.com/ocsp/status0
    • https://www.verisign.com/rpa0
    • http://crl.microsoft.com/pki/crl/products/CodeSignPCA.crl0

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
embedded_office_00018200.exe
e333ff01ff2015c68ad0c4c77b2202ae5c220ccfd0e5ee6d068fe1b34d336061		 embedded-pe Office MZ+PE at offset 0x18200 45316 bytes

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