Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 da1603347c0b5bf7…

MALICIOUS

RTF / .DOC

1.66 MB First seen: 2022-05-09
MD5: 5bdaeeded0643b6901448b5fc57246ab SHA-1: 2273972c7879a952d089e851c8c6c4766da23aa3 SHA-256: da1603347c0b5bf74d8e32d0a4f112d5fd5f10fa4b50dad769c9afaadd87cfe8
180 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: Component Object Model Hijacking

The file is an RTF document that contains embedded OLE objects, specifically exploiting CVE-2017-11882 via the Equation Editor. This vulnerability allows for the execution of arbitrary code when the document is opened. The presence of `Equation.3` in the heuristics strongly indicates this exploit 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000012ab.bin
df5bdd2d460ce31a1707e69cd33de37834e3a08167c7c1b6998a0f034e7a0eb7		 rtf-objdata-decoded RTF \objdata at offset 0x12AB 100670 bytes
objdata_01_off000461bd.bin
c6836530895d3068b0bd13b6673e20cfb3c2472da47cd4c3fb2419898144731b		 rtf-objdata-decoded RTF \objdata at offset 0x461BD 345132 bytes

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