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

Static analysis result for SHA-256 79dbf77dd898d0a2…

MALICIOUS

Office (OLE) / .XLS

434.6 KB Authoring application: Microsoft Excel
MD5: e690de5d2cb7da1c3161d5a23b60a1aa SHA-1: 33712ba0bbb561a7d6cd76a50052def76610aad8 SHA-256: 79dbf77dd898d0a2bf4608c41480a84922f3f18f0f4117ab353eac2488fd7aef
168 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file is an Excel spreadsheet containing VBA macros. Heuristics indicate the presence of XOR-encoded strings and an appended payload, suggesting the macros are used to download and execute a malicious second-stage payload. The VBA project itself contains no executable statements, implying the malicious code is likely obfuscated or dynamically generated.

Heuristics 5

  • XOR-encoded strings (key 0xDE) critical SC_XOR_ENCODED
    Found 5 Windows library/API name(s) XOR-encoded with single-byte key 0xDE: 'GetProcAddress', 'CreateProcessA', 'ExitProcess', 'CreateFileA', 'CreateFileW'
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 445,026 bytes but its declared streams total only 240,528 bytes — 204,498 bytes (46%) 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
  • VBA project contains no executable statements low OLE_VBA_MACROS
    Document contains a VBA project, but extracted modules only contain attributes/options/comments and no executable statements.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
481031c20227961d1e7d207d0bb17c79a9001efbdb37ac509a4ff93acb047bf0
vba-macro oletools.olevba.extract_macros (decoded VBA source) 606 bytes