Malicious RTF — malware analysis report

Static analysis result for SHA-256 d850254250538d63…

MALICIOUS

RTF

8.2 KB First seen: 2018-11-13
MD5: 9d501fca68959aef59f9e6999ff863fe SHA-1: 1e153db101eb732c604b24001df8b41ff2634782 SHA-256: d850254250538d631791d720c3e00eeb016cc3c64d6eb55912cdbd7953574d27
240 Risk Score

Malware Insights

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

The sample is an RTF document containing embedded OLE object data. Heuristics indicate a critical vulnerability in Equation Editor (CVE-2017-11882) is being exploited, which allows for client-side code execution. The presence of ".objupdate" further suggests an attempt to force OLE activation. This exploit is commonly delivered via spearphishing attachments.

Heuristics 5

  • 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: Doc.Exploit.CVE_2017_11882-6934206-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Exploit.CVE_2017_11882-6934206-0
  • \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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000003c.bin rtf-objdata-decoded RTF \objdata at offset 0x3C 4151 bytes
SHA-256: 0086e50ce178c9433592640c3c9f5b2288f5033b9f8769a468c20cd34527da20