Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 d8be489d36a5af45…

MALICIOUS

RTF / .DOC

1.96 MB First seen: 2022-03-08
MD5: 897a5ac73137a8b00c824acfce627c73 SHA-1: 1df1bc70d58910cb5c09e42551322d91d3b8dcf6 SHA-256: d8be489d36a5af4577d16f15590dc01ada20f700d706e30b103d6429db8ae2f4
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF document contains embedded OLE objects and specifically triggers the CVE-2017-11882 vulnerability through the Equation Editor. The decoded object data appears to contain VBScript code that attempts to execute a file named 'client.vbs' and potentially uses PowerShell commands. This indicates a likely exploit delivery mechanism aiming to execute a second-stage 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_off000012c5.bin
a1da093a34c437a5e9405735d53f9ab0cd8ecb2d4e564c0e50cd1dff1e1f0903		 rtf-objdata-decoded RTF \objdata at offset 0x12C5 27039 bytes
objdata_01_off00019f8c.bin
fd387bf73715ad3ddffb484923b15f1a6a20c79bd947b60b91bae40d9d4fb788		 rtf-objdata-decoded RTF \objdata at offset 0x19F8C 462937 bytes

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