Malicious RTF — malware analysis report

Static analysis result for SHA-256 668f22336a337005…

MALICIOUS

RTF

1.96 MB First seen: 2022-03-08
MD5: df5610a824c1955a1974ab9584125875 SHA-1: 984756f2b6564b566a747adf57e3d49f92adcb6e SHA-256: 668f22336a33700507b6572eb14d9777f9459958c3d6d62e589e3c972dbac340
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that leverages the CVE-2017-11882 vulnerability in Microsoft Equation Editor. The ".objupdate" directive forces the activation of this object, leading to the execution of a second-stage payload. The presence of the Equation Editor ProgID "Equation.3" is a strong indicator of this exploit.

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
764338524e31d57ccc324d1c4f0583f5956011f71a1503558d7094704a52707b		 rtf-objdata-decoded RTF \objdata at offset 0x12C5 27030 bytes
objdata_01_off00019f7a.bin
fd387bf73715ad3ddffb484923b15f1a6a20c79bd947b60b91bae40d9d4fb788		 rtf-objdata-decoded RTF \objdata at offset 0x19F7A 462937 bytes

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