Malicious RTF — malware analysis report

Static analysis result for SHA-256 db0790e031fb6027…

MALICIOUS

RTF

2.08 MB First seen: 2022-03-21
MD5: 7ec4fb7aac538d79faa4df7d3bfa8010 SHA-1: 96da0b41f3d49acc22187d715de67054f38fff40 SHA-256: db0790e031fb6027df340597b124fba2873be21053e2c47419f323ca7489e941
180 Risk Score

Malware Insights

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

The RTF document contains multiple indicators of exploitation for CVE-2017-11882, specifically related to the Equation Editor. The presence of OLE object data and the explicit firing of the CVE_2017_11882_ACTIVATION_RELATED heuristic strongly suggest this vulnerability is being leveraged. The decoded object data contains what appears to be VBScript code, including references to 'client.vbs' and a path 'c:\path\client.vbs', indicating the likely execution of a malicious script 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_off00001291.bin
af914734c6f34c70184c48fb200771f00800dd953171aa0215f96d53846e8066		 rtf-objdata-decoded RTF \objdata at offset 0x1291 86173 bytes
objdata_01_off00036d20.bin
0d5b281ccf06cde67f96a47d088699b424d7becc45a1722303f91b6e9b4024f2		 rtf-objdata-decoded RTF \objdata at offset 0x36D20 463413 bytes

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