Malicious RTF — malware analysis report

Static analysis result for SHA-256 2f667e613e8290a5…

MALICIOUS

RTF

860.8 KB First seen: 2022-09-20
MD5: 5f3a406ac800eeffad38b9b0aac80316 SHA-1: 01e8a20de4088abd715ea9ac3dc1357431b4006f SHA-256: 2f667e613e8290a5abeb2029512d5f95b9d8edb0413dc848faf85fdf87c69a2f
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). The ".objupdate" directive forces the activation of this object, triggering the exploit. The embedded object's ProgID is 'Equation.3', indicating the use of the vulnerable Equation Editor component. The decoded object data suggests the potential execution of a script, likely to download and run a secondary payload.

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_off000012b8.bin
94b89e0fdbc42021238fc01ea9f8494798edf16c92ecf8ecd6b67f771d223b07		 rtf-objdata-decoded RTF \objdata at offset 0x12B8 81452 bytes
objdata_01_off0002f0a8.bin
8241f500b6f66c0010a61e3e66b293b7e5e246b297d9c6a44403288dc5895294		 rtf-objdata-decoded RTF \objdata at offset 0x2F0A8 140710 bytes

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