Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 83c82ddedee67b7c…

MALICIOUS

RTF / .DOC

37.8 KB First seen: 2023-01-17
MD5: a468dbb8766af7a35f7bfcf42a9b4ada SHA-1: a1c179cf92b79a705bf2de82aa7fc78f5ea4809f SHA-256: 83c82ddedee67b7caf67d6e7e750ffd810fefe9a6aaf6f55aae4bcf6af538525
220 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Phishing: Spearphishing Attachment T1204.002 Malicious File: Malicious Attachment T1059.005 Command and Scripting Interpreter: Visual Basic

The sample is an RTF document containing an embedded OLE object specifically identified as related to CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The presence of RTF_OBJAUTLINK, RTF_EQUATION_EDITOR, and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates exploitation of this vulnerability. The SE_ENABLE_LURE heuristic suggests the document prompts the user to enable content, a common social engineering tactic to bypass security measures. The primary goal appears to be the execution of a second-stage payload via the exploited vulnerability.

Heuristics 6

  • 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00007864.bin
7e42da24c3eec51619ca83c9491dd730715b88d376b406643ca48771a90ab657		 rtf-objdata-decoded RTF \objdata at offset 0x7864 1933 bytes

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