Malicious RTF — malware analysis report

Static analysis result for SHA-256 1d4d5803b70bb823…

MALICIOUS

RTF

7.9 KB Authoring application: Riched20 6.3.9600 First seen: 2019-11-20
MD5: 3851d26114c4609d8c0540ec17aac806 SHA-1: e73788fcac14e34d4fac196a86691fd3d3d13f11 SHA-256: 1d4d5803b70bb82314b9a06c484958c4ab17929b8ef69e6df6474c15359a2e0c
322 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 exploits CVE-2017-11882 in the Equation Editor. This vulnerability allows for arbitrary code execution, likely to download and execute a second-stage payload from the embedded URL http://192.168.0.172:8080/noCAcc.sct. The presence of the Equation Editor CLSID and the ".objupdate" directive strongly indicate this exploit.

Heuristics 8

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882
    Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
  • ClamAV: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
  • Equation Editor object class critical RTF_OBJCLASS_EQUATION
    Object class 'equation.3' references Equation Editor
  • \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
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://192.168.0.172:8080/noCAcc.sct In RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000fe.bin rtf-objdata-decoded RTF \objdata at offset 0xFE 3546 bytes
SHA-256: 461843ef7e5cd021d85a70642bf86a61adb542eb07dc645b4d939f9ffc265cd3

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