Multiple PDF samples are discovered in the wild which exploit a Google Chrome unpatched ﬂaw. The exploited vulnerability allows the sender of the PDF ﬁles to track the users and collect some user information when they use Google Chrome as a local PDF viewer.
These samples acted alright in the local PDF viewer but made suspicious outbound traﬃc when they were opened locally on Google Chrome.
Researchers observed that data was being sent to readnotify[.]com without informing user. The traﬃc is a HTTP POST packet, according to which following information of the user may be collected by the malicious sender:
This aﬀects Google Chrome (as local PDF viewer), not Adobe Reader and does not allow NTLM stealing, but it leaks your OS information and the path of the ﬁle stored on your local disk.
Another PDF sample cpmmunicated with hxxp[:]//zuxjk0dftoamimorjl9dfhr44vap3fr7ovgi76w[.]burpcollaborator[.]net
Personal Information Disclosure
Indicators of Compromise
IP(s) / Hostname(s)
Malware Hash (MD5/SHA1/SH256)