Office (OLE) / .XLS malware analysis — malicious · ff5a07d44ac4c69a

MALICIOUS

Office (OLE) / .XLS

229.5 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel

MD5: da912912d1202b7f03626e5ec0d12a0a SHA-1: 17acd2f484b7dd34beadc3cf6d45cc834439bb24 SHA-256: ff5a07d44ac4c69afe13a51edcc018fd503dc00da838064cb599ed870bdb8ae9

220 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The sample is an Excel file exhibiting high-severity heuristics related to WinExec, LoadLibrary, and GetProcAddress API calls, indicating a strong likelihood of code execution. Additionally, it contains XOR-encoded strings and a significant slack space anomaly typical of packed or obfuscated malware. The presence of these indicators suggests the file is designed to download and execute a secondary payload.

Heuristics 5

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 235,008 bytes but its declared streams total only 24,565 bytes — 210,443 bytes (90%) 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).

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