Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 acd2748277c8df69…

MALICIOUS

RTF / .DOC

2.05 MB First seen: 2022-04-27
MD5: 699bafb6ad58024dc155df0964d0f796 SHA-1: 8cbb093bc6b2ab9a8242cf14ed5c7ab21032d193 SHA-256: acd2748277c8df695702f38079ff81a8e31a98c1c689d8c2a64dbac200586e78
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is an RTF document containing an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). The `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics confirm this. The `RTF_OBJUPDATE` heuristic indicates that the OLE object is forced to activate upon opening the document, leading to arbitrary code execution. The embedded OLE object likely contains a script or payload designed to further compromise the system.

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
6f5ca15498031c99b616f8562e61b7d7ccb55c5e046892805327eae8cd46416d		 rtf-objdata-decoded RTF \objdata at offset 0x12AB 86011 bytes
objdata_01_off00036c10.bin
15b7f137c999929be510fea7aaa1c34a11c506a87bc2b1d42d45986f1d905f44		 rtf-objdata-decoded RTF \objdata at offset 0x36C10 457432 bytes

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