Malicious RTF — malware analysis report

Static analysis result for SHA-256 c720344b0c46df19…

MALICIOUS

RTF

17.3 KB First seen: 2020-09-15
MD5: fa1024c8e8dd099980c5a2cb3b8a1dc0 SHA-1: be46ba65c6c3fe6f6d52ba73b10ed1990e7b4ea9 SHA-256: c720344b0c46df19bd5297626f005bcfd9c794376a4d86be885472aac92336ae
180 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object that triggers CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. This exploit allows for arbitrary code execution, which is typically used to download and run a second-stage malware payload. The specific class name 'equaTION.3' is a strong indicator of this exploit.

Heuristics 5

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • 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.
  • \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 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001770.bin rtf-objdata-decoded RTF \objdata at offset 0x1770 1584 bytes
SHA-256: b5ab55b877473fe73db1d414db5bb10ad639256849956f75b78d52558384511e

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