Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 81aaf53e0d025228…

MALICIOUS

RTF / .DOC

1.69 MB
MD5: eba6f97891e9a26694480522670f2e28 SHA-1: ae7d77470c16360dec75155a5afe931ea85ccf83 SHA-256: 81aaf53e0d025228ed4eae33a46f8dcbb42035969c2abc7e8a5bbf7bd2f34abe
260 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The RTF document contains multiple indicators of exploitation for CVE-2017-11882, specifically through the use of OLE objects and the Equation Editor. The presence of a large, hex-encoded OLE object within the RTF structure strongly suggests it is designed to deliver a secondary payload. The exploitation of the Equation Editor is a known method for initial execution of malicious code.

Heuristics 6

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
  • 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1745KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000ab.bin
b719e09640a8972b531a757f7f6eac092e8a9dac2d7f443b842c77ed5a43140e		 rtf-objdata-decoded RTF \objdata at offset 0xAB 875233 bytes

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