Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 689f7b98fa16dbaa…

MALICIOUS

RTF / .DOC

1.58 MB
MD5: c8021beb65a3b037f396cd8c6da6b9c4 SHA-1: ccd8b7b2ba5a0fa3635250d4fb559e28ce2ed630 SHA-256: 689f7b98fa16dbaa44e98118e88e4eef4e8c12565288b3ba62821a851b36e97d
260 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object specifically identified as related to CVE-2017-11882, exploiting the Equation Editor vulnerability. This exploit is designed to execute arbitrary code, likely to download and run a secondary malicious payload. The presence of multiple high and critical heuristics related to OLE objects and Equation Editor strongly indicates this exploit vector.

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 ~1656KB 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_off0000153e.bin
8bebd27f338efee8a7ee419f1883b55120324014c15cc17c76a0448397d63e82		 rtf-objdata-decoded RTF \objdata at offset 0x153E 828053 bytes

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