Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 817317886b976d2d…

MALICIOUS

RTF / .DOC

1.91 MB First seen: 2022-03-23
MD5: af48abba8f1dde9eac45c576101440ee SHA-1: e5fd5448fc1480ee86dc9c8786f804dd1526b5ff SHA-256: 817317886b976d2d2a0303782fabc99b8602820f69944dfb74b1d684d9d91494
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains critical heuristics indicating the exploitation of CVE-2017-11882 via the Equation Editor OLE object. This vulnerability is known to be used for arbitrary code execution, likely to download and run a secondary payload. The large amount of hex-encoded data within the OLE object further suggests the presence of a hidden payload.

Heuristics 5

  • 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.
  • \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 ~1996KB 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_off00000685.bin
12fd47bd863cc1170fcde03fa8db97201e5a3045e07d927a9f4e5c168b68ec21		 rtf-objdata-decoded RTF \objdata at offset 0x685 998106 bytes

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