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

Static analysis result for SHA-256 58d3874b9b59eb29…

MALICIOUS

Office (OLE) / .XLS

218.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: c083922bf5652bccd3f78e9f8013f5c3 SHA-1: 498ccc899617584062f8544899a631d7e2a0129d SHA-256: 58d3874b9b59eb29a09e16f7d1577d84f479a9a500f67f832387c27fe959edd1
200 Risk Score

Malware Insights

MITRE ATT&CK
T1140 Deobfuscate or Decode Files or Information T1553.005 Mark-of-the-Web Bypass

The file is a malicious Excel spreadsheet exhibiting several high-severity heuristic firings, including NOP sleds, XOR-encoded strings, and an embedded PE executable. The presence of an embedded executable suggests the file's primary purpose is to download and execute a secondary payload. The XOR encoding with key 0xD5 indicates a deliberate attempt to obfuscate malicious content. While no specific family is identified, the combination of techniques points to a downloader or droppper malware.

Heuristics 6

  • XOR-encoded strings (key 0xD5) critical SC_XOR_ENCODED
    Found 1 Windows library/API name(s) XOR-encoded with single-byte key 0xD5: 'kernel32.dll'
  • NOP sled detected high SC_NOP_SLED
    Found 20+ consecutive 0x90 bytes
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 223,263 bytes but its declared streams total only 24,565 bytes — 198,698 bytes (89%) 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 PE executable high OLE_EMBEDDED_EXE
    MZ/PE header found inside document — possible embedded executable
  • NOP-equivalent sled detected medium SC_NOP_EQUIV_SLED
    Long run of 0x40 bytes
  • 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://ocsp.verisign.com0
    • http://ocsp.thawte.com0
    • http://crl.thawte.com/ThawtePremiumServerCA.crl0
    • http://crl.verisign.com/tss-ca.crl0
    • http://crl.verisign.com/ThawteTimestampingCA.crl0
    • http://crl.thawte.com/ThawteCodeSigningCA.crl0
    • http://www.360.cn

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