Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 e0e52a8ad589d785…

MALICIOUS

RTF / .DOC

3.5 KB First seen: 2021-10-11
MD5: a6a7200cc618b877fbb66b8618cf4d6a SHA-1: cf7a2eecf49ea9471323c3477e1e6eb8d97ac0d2 SHA-256: e0e52a8ad589d785096ae234cf374433e6329840506345adb8ec12ae3ebc85f1
180 Risk Score

Malware Insights

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

The RTF document contains embedded OLE objects, specifically triggering the Equation Editor vulnerability (CVE-2017-11882). The presence of ".objupdate" and the decoded object data strongly indicate that the file is designed to exploit this known vulnerability, likely leading to arbitrary code execution. No document body or scripts were extracted, but the heuristics are sufficient to identify the attack vector.

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_off000000a2.bin
32dcf1c8da9f9efbc514f94cea7c9b0959a709305003ac6c92a14490a20d238d		 rtf-objdata-decoded RTF \objdata at offset 0xA2 1441 bytes

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