Malicious RTF — malware analysis report

Static analysis result for SHA-256 ae24b698e09dac29…

MALICIOUS

RTF

2.61 MB First seen: 2022-05-31
MD5: 7d4e52a5bd75c7ff8daf09345f78499f SHA-1: 30981c7f006d5e87e18dcb8c42c1dba483b85947 SHA-256: ae24b698e09dac292d70f7315b83a657c54eeffeefc562faf6b9e2d4618cd137
340 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.001 PowerShell

The RTF document contains embedded OLE objects and specifically targets the Equation Editor vulnerability (CVE-2017-11882). The presence of a PE header within the hex data and the ClamAV detection as Rtf.Dropper.Agent-9965975-1 strongly indicate that this file is a dropper designed to execute a malicious payload, likely the embedded 'Client.exe' located at 'C:\Path\Client.exe'. The exploit facilitates the initial execution of this payload.

Heuristics 8

  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • PE header (with DOS stub) in hex data critical RTF_MZ_HEX
    Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
  • ClamAV: Rtf.Dropper.Agent-9965975-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-9965975-1
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000129e.bin
07eb3d01274162d044322d1c919487c1202f2e2602a06cc907f8ce5515b028b6		 rtf-objdata-decoded RTF \objdata at offset 0x129E 368939 bytes
objdata_01_off000c0e56.bin
c15a908dd43ec603b552f3652117fbcce46d419a9a10490458118a5a4409d1b8		 rtf-objdata-decoded RTF \objdata at offset 0xC0E56 462749 bytes

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