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

Static analysis result for SHA-256 b428cc6999454f6d…

MALICIOUS

Office (OLE) / .XLS

115.0 KB
MD5: 34e665e62e5eaf73b55ea14efd2e3bcf SHA-1: d578bd17fdcd6bacecaba11cb2b979a6febc4642 SHA-256: b428cc6999454f6dc83c7960972fb81566d526a20028e7d41a1c9de82ac5b04f
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The sample is an OLE Excel file exhibiting a large slack space anomaly, indicative of hidden data. Heuristics indicate the presence of WinExec, LoadLibrary, and GetProcAddress APIs, along with XOR-encoded strings, suggesting code execution and obfuscation. These findings, combined with the embedded URL, point towards a macro-based downloader attempting to fetch and execute a second-stage payload. The benign reputation of the extracted URLs does not preclude their use in a malicious context.

Heuristics 6

  • XOR-encoded strings (key 0x03) critical SC_XOR_ENCODED
    Found 8 Windows library/API name(s) XOR-encoded with single-byte key 0x03: 'VirtualAlloc', 'VirtualAlloc', 'VirtualAllocEx', 'VirtualProtect', 'VirtualProtectEx', 'CreateProcessA', 'WriteProcessMemory', 'ReadProcessMemory'
  • Reference to WinExec API high SC_STR_WINEXEC
    Reference to WinExec API
  • 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 117,760 bytes but its declared streams total only 56,346 bytes — 61,414 bytes (52%) 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).
  • 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

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