Exploit detection service EdgeSpot says it has spotted several PDF documents that exploit a zero-day vulnerability in Chrome to collect information on users who open the files through Google’s web browser.
EdgeSpot claims to have identified several samples in the wild. When one of the PDFs is opened with Chrome, a document is shown to the user, but various pieces of information are collected and sent to a remote server in the background.
Researchers say there is no suspicious activity when the files are opened using a viewer such as Adobe Reader, but outbound traffic has been detected when they are opened with Chrome.
EdgeSpot says the specially crafted documents, which have been observed since late December, collect data such as IP address, operating system and Chrome versions, and the full path of the PDF file on the victim’s system.
The data is sent via an HTTP POST request to a remote server without requiring any user interaction. The samples analyzed by the researchers have been sending the data to one of two domains: burpcollaborator.net or readnotify.com.
A screenshot posted by EdgeSpot shows that one of the malicious files was a modified version of a document from Lonely Planet on the history of the Bay Islands in Honduras. Based on the names of the malicious files, they all appear to reference Honduras.
A majority of the samples found by EdgeSpot have very low detection rates on VirusTotal at the time of writing – they are either marked as “clean” by all antiviruses or they are detected by only 2-3 products.
EdgeSpot said it reported its findings to Google on December 26. However, it claims that Chrome developers only plan on rolling out a fix in late April. SecurityWeek has reached out to Google for comment and will update this article if the company responds.
“We decided to release our finding prior to the patch because we think it’s better to give the affected users a chance to be informed/alerted of the potential risk, since the active exploits/samples are in the wild while the patch is not near away,” EdgeSpot said.
Until a patch is released, users have been advised to avoid opening suspicious PDF documents via Chrome and use other PDF viewers.
Adobe also released patches recently for some Reader vulnerabilities that can be exploited to harvest user data via PDF files.
Related: Attackers Use Steganography to Obfuscate PDF Exploits