Polyglot | Breaking Cybersecurity News | The Hacker News

Cybersecurity researchers have called attention to a new antivirus evasion technique that involves embedding a malicious Microsoft Word file into a PDF file. The sneaky method, dubbed  MalDoc in PDF  by JPCERT/CC, is said to have been employed in an in-the-wild attack in July 2023. "A file created with MalDoc in PDF can be opened in Word even though it has magic numbers and file structure of PDF," researchers Yuma Masubuchi and Kota Kino  said . "If the file has a configured macro, by opening it in Word, VBS runs and performs malicious behaviors." Such specially crafted files are called  polyglots  as they are a legitimate form of multiple different file types, in this case, both PDF and Word (DOC). This entails adding an MHT file created in Word and with a macro attached after the PDF file object. The end result is a valid PDF file that can also be opened in the Word application. Put differently; the PDF document embeds within itself a Word document with a VB

Remote access trojans such as StrRAT and Ratty are being distributed as a combination of polyglot and malicious Java archive ( JAR ) files, once again highlighting how threat actors are continuously finding new ways to fly under the radar. "Attackers now use the polyglot technique to confuse security solutions that don't properly validate the JAR file format," Deep Instinct security researcher Simon Kenin  said  in a report. Polyglot files  are files that combine syntax from two or more different formats in a manner such that each format can be parsed without raising any error. One such 2022 campaign spotted by the cybersecurity firm involves the use of JAR and MSI formats – i.e., a file that's valid both as a JAR and an MSI installer – to deploy the StrRAT payload. This also means that the file can be executed by both Windows and Java Runtime Environment (JRE) based on how it's interpreted. Another instance involves the use of CAB and JAR polyglots to deli