Virtual Event Today: Supply Chain Security Summit - Register Now

Security Experts:

Connect with us

Hi, what are you looking for?


Malware & Threats

Malware Dropper Supports a Dozen Decoy Document Formats

A recently discovered malware dropper has the ability to use nearly a dozen decoy document file formats to drop various payloads, Palo Alto Networks security researchers warn. 

A recently discovered malware dropper has the ability to use nearly a dozen decoy document file formats to drop various payloads, Palo Alto Networks security researchers warn. 

Dubbed CARROTBAT, the customized dropper is being used to deliver lures primarily pertaining to the Korean region, revolving around subjects such as crypto-currencies, crypto-currency exchanges, and political events. 

A December 2017 attack against a British government agency, which employed the SYSCON remote access Trojan (RAT), allowed the security researchers to discover the CARROTBAT dropper due to infrastructure overlaps. 

To date, Palo Alto Networks identified 29 unique CARROTBAT samples, containing a total of 12 confirmed unique decoy documents. The dropper first emerged in March 2018, but most of its activity was observed over the past three months. 

The threat was observed delivering a variety of payloads, such as SYSCON in older variants, and the OceanSalt malware family in newer samples. 

CARROTBAT employs rudimentary command obfuscation, but is not sophisticated, despite its support for various types of decoy documents, the security researchers say. 

The attacks featuring CARROTBAT, which Palo Alto Networks refers to as Fractured Block, featured all dropper samples identified to date, and 11 decoy document file formats supported by the malware, namely .doc, .docx, .eml, .hwp, .jpg, .pdf, .png, .ppt, .pptx, .xls, and .xlsx. 

The malware can drop and open the embedded decoy file, after which a command to download and run a payload on the targeted machine is executed. The payload is downloaded and executed via the Microsoft Windows built-in certutil utility. 

The identified CARROTBAT samples have been compiled between March 2018 and September 2018, based on their timestamps. Between March and July, the dropper delivered multiple instances of SYSCON. Starting June, OceanSalt also started being served to the victims, and the attacks featuring this malware family continue to date. 

The CARROTBAT infrastructure was also observed overlapping with that of KONNI, a RAT that is believed to have been in use for over four years and which has been historically focusing on targets in the Southeast Asia region. 

In March of this year, McAfee also detailed a series of attacks attributed to a threat actor interested in inter-Korean affairs and which used both SYSCON and KONNI for compromise purposes. 

“Using CARROTBAT, we were able to find related OceanSalt, SYSCON and KONNI activity. The various overlaps encountered are notable, and it is our suspicion that this threat activity may all belong to the same threat actor. However, we do not believe there to be enough evidence at this time to make this claim with complete certainty,” Palo Alto Networks concludes. 

Related: ‘Operation Oceansalt’ Reuses Code from Chinese Group APT1

Related: New Malware Used in Attacks Aimed at Inter-Korean Affairs

Written By

Ionut Arghire is an international correspondent for SecurityWeek.

Click to comment

Daily Briefing Newsletter

Subscribe to the SecurityWeek Email Briefing to stay informed on the latest threats, trends, and technology, along with insightful columns from industry experts.

Join this webinar to learn best practices that organizations can use to improve both their resilience to new threats and their response times to incidents.


Join this live webinar as we explore the potential security threats that can arise when third parties are granted access to a sensitive data or systems.


Expert Insights

Related Content


The changing nature of what we still generally call ransomware will continue through 2023, driven by three primary conditions.


No one combatting cybercrime knows everything, but everyone in the battle has some intelligence to contribute to the larger knowledge base.


A recently disclosed vBulletin vulnerability, which had a zero-day status for roughly two days last week, was exploited in a hacker attack targeting the...

Malware & Threats

Threat actors are increasingly abusing Microsoft OneNote documents to deliver malware in both targeted and spray-and-pray campaigns.

Malware & Threats

Microsoft plans to improve the protection of Office users by blocking XLL add-ins from the internet.


More than 3,800 servers around the world have been compromised in recent ESXiArgs ransomware attacks, which also include an improved process.

Malware & Threats

A vulnerability affecting IBM’s Aspera Faspex file transfer solution, tracked as CVE-2022-47986, has been exploited in attacks.

Malware & Threats

Unpatched and unprotected VMware ESXi servers worldwide have been targeted in a ransomware attack exploiting a vulnerability patched in 2021.