Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 250f055b865b458b…

MALICIOUS

RTF / .DOC

10.1 KB First seen: 2022-12-31
MD5: 33a2f4f2c6964af11817db9061bd9948 SHA-1: fe4b48b370d007977c5ee831e9a151427afd7b58 SHA-256: 250f055b865b458bcdec1e6936308da522d3effd9ad0fc45dad3f458565ab533
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1559.001 Component Object Model

The sample is an RTF document that contains an embedded OLE object, specifically identified as an Equation Editor object. Heuristics indicate the exploitation of CVE-2017-11882, which is a known vulnerability allowing for arbitrary code execution when the Equation Editor is activated. The presence of `EquaTiON.3` further confirms the use 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_off00001d02.bin
fb2a7e2ffa1f08ae53b25f64b0fad56e38ccfd89150568c2030b34c3447f066f		 rtf-objdata-decoded RTF \objdata at offset 0x1D02 1388 bytes

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