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

Static analysis result for SHA-256 31c2a0be2d738480…

MALICIOUS

Office (OLE) / .XLS

66.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: abf8376f79c5cf8131bfb9c9a3de6917 SHA-1: 49610d42719c94d6f92ee40e92919450cc63dc2a SHA-256: 31c2a0be2d738480426107f3102e9827b19ee913404e1e5a11b553aa77c629c0
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 known vulnerability in Microsoft Excel. The presence of references to VirtualProtect, LoadLibrary, and GetProcAddress APIs suggests that the exploit likely loads and executes a malicious payload. The large slack space in the OLE structure is also indicative of a packed or obfuscated 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=22, isf=4, cbHdrData=4). 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 67,584 bytes but its declared streams total only 24,565 bytes — 43,019 bytes (64%) 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 VirtualProtect API medium SC_STR_VIRTUALPROTECT
    Reference to VirtualProtect API