Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 36f025547972c566…

MALICIOUS

RTF / .DOC

2.07 MB First seen: 2022-03-10
MD5: 58b0568aee755368ce30b6bb368bd189 SHA-1: 05b403d255355a477edb6225b476595b758804e7 SHA-256: 36f025547972c566f4614bdc0493064d4e802bd8ff25c3290d69c735082f8f85
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that exploits CVE-2017-11882 through the Equation Editor. The DOC BODY excerpt reveals VBA code that appears to be related to license management, potentially a lure. The primary mechanism of infection is the exploitation of the Equation Editor vulnerability, leading to the execution of malicious code.

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_off000012c5.bin
066febbbe1f9d0ada315bb71e2b5f9fe0986edbc640627b71879117c29befa98		 rtf-objdata-decoded RTF \objdata at offset 0x12C5 84150 bytes
objdata_01_off00035dba.bin
1f4b66471b5f67e5ffc304099fa7ac8bb36a8fa8369c9fb77f5892326cd7ef16		 rtf-objdata-decoded RTF \objdata at offset 0x35DBA 462938 bytes

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