Xls.Dropper.Agent-7056842-0 — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 a6722c3f5e661bf0…

MALICIOUS

Office (OLE) / .XLS

107.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: 31ad3199a07c766eb9c1b0a85edfc94b SHA-1: 8da439069c179261d6f98c66bac4f2e8bd51b418 SHA-256: a6722c3f5e661bf0cdeedf9c29c84da2df00b58ef56fe8a3f5e8b4353a15ef36
160 Risk Score

Malware Insights

Xls.Dropper.Agent-7056842-0 · confidence 95%

MITRE ATT&CK
T1204.002 Malicious File T1566.001 Spearphishing Attachment T1204 User Execution

The file is identified as malicious by ClamAV as Xls.Dropper.Agent-7056842-0. Static analysis revealed a critical vulnerability, CVE-2009-3129, related to an Excel FEATHEADER record overflow. Additionally, a large amount of slack space was detected in the OLE document, which is often used to hide malicious content. The combination of these factors strongly suggests the file is a dropper designed to exploit this vulnerability and deliver a secondary payload.

Heuristics 3

  • 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.
  • ClamAV: Xls.Dropper.Agent-7056842-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-7056842-0
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 109,592 bytes but its declared streams total only 24,565 bytes — 85,027 bytes (78%) 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).