Office (OLE) / .XLS malware analysis — malicious · 0b6a94649a7f76db

MALICIOUS

Office (OLE) / .XLS

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

MD5: 02cb43502a4c29392b90ef851ee92a05 SHA-1: e3ad7b3a6ca1b4ceb25ba1d83de9164e502f5a1b SHA-256: 0b6a94649a7f76db1847b6c13c5287825d919da0731ac62fb82bac1832f1288f

200 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution

The critical heuristic firing for CVE-2009-3129 indicates that this Excel file is designed to exploit a buffer overflow vulnerability. The presence of VirtualAlloc, LoadLibrary, and GetProcAddress API calls further suggests that the exploit is used to load and execute arbitrary code, likely a second-stage payload.

Heuristics 5

CVE-2009-3129 — Excel FEATHEADER record overflow critical CVE exact CVE_2009_3129

Workbook BIFF stream contains a FEATHEADER (Feature Header) record with anomalous size (record_size=23, isf=2, cbHdrData=4294967295). Legitimate FEATHEADER records are tiny (<100 bytes) and carry cbHdrData values that fit in the record body; the value here is the documented CVE-2009-3129 exploit primitive — cbHdrData drives a memcpy with attacker-controlled size, leading to memory corruption and code execution in Excel 2007/2003.
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 155,648 bytes but its declared streams total only 24,565 bytes — 131,083 bytes (84%) 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

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