Malicious RTF — malware analysis report

Static analysis result for SHA-256 896dc496aea89982…

MALICIOUS

RTF

4.0 KB First seen: 2021-05-26
MD5: c6e47432eea3fd2f14cb31e744fe198a SHA-1: 8a70f22e1d78e08a675f4d46415fcbe68a0ac528 SHA-256: 896dc496aea89982f7a7db6040025719d1a8a5e205dc52ce566fc99c4becd84e
180 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object with a split Equation Editor ProgID, strongly indicating exploitation of CVE-2017-11882. The ".objupdate" directive forces OLE activation, which is a common method for executing arbitrary code. This technique is typically delivered via spearphishing attachments.

Heuristics 5

  • 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.
  • 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.
  • 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000d3.bin rtf-objdata-decoded RTF \objdata at offset 0xD3 1787 bytes
SHA-256: c0e09627a48fc0c5351aa3f8351142abcde73528479e1e8b5f3797d07f619587

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