Researchers Uncover New Drokbk Malware that Uses GitHub as a Dead Drop Resolver
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2021-44228 | JNDI Injection Remote Code Execution in Apache Log4j2 (Log4Shell) Apache Log4j2, an extremely widely used Java logging library, fails to protect its JNDI lookup feature against attacker-controlled JNDI-related endpoints (CWE-20, CWE-502), so crafted text processed by the logger causes the Java runtime to fetch and load attacker-supplied objects, leading to remote code execution. The flaw is triggered whenever attacker-controlled input reaches the logging API and is parsed for JNDI lookups, a pattern common in web servers and enterprise Java applications that log user-supplied fields such as headers or form values. Successful exploitation yields arbitrary code execution under the privileges of the affected application, giving attackers a foothold for lateral movement, data theft, and ransomware deployment. Any Java application or product that ships or bundles an affected Apache Log4j2 release is exposed, making this one of the most broadly deployed vulnerabilities ever disclosed. Exploitation is confirmed in the wild: CISA added it to the Known Exploited Vulnerabilities catalog on 2021-12-10 with known ransomware use, and EPSS assigns a 100% probability of exploitation within 30 days. Do: Inventory all Java applications and dependencies for Apache Log4j2 and apply the vendor's patched updates, or remove affected assets from the network, as required by CISA's KEV catalog. Where updates are not yet available, use the temporary mitigations in CISA's ED-22-02 recommended-mitigation guidance, such as disabling message lookups, only until patches are applied. Prioritize internet-facing and business-critical systems and hunt for exploitation activity given known ransomware use. | 10.0 | 100% | KEV ransomware PoC ×9 |
| masshundreds of millions of Java applications/devices, with hundreds of thousands of internet-exposed services | |
| CVE-2021-45046 | Remote Code Execution in Apache Log4j2 via Incomplete Log4Shell Fix CVE-2021-45046 is a remote code execution and information disclosure flaw in Apache Log4j2 (CWE-917) that resulted from an incomplete fix to CVE-2021-44228 (Log4Shell), leaving the Thread Context Lookup Pattern vulnerable in certain non-default configurations. It is triggered when an application logs attacker-controlled data using layouts or patterns that perform Thread Context (MDC) lookups, allowing crafted lookup expressions to be evaluated against untrusted input. A successful attacker can achieve remote code execution, or potentially information disclosure, on the affected service. Any deployment of Apache Log4j2 that relies on the affected non-default lookup configurations is exposed, which given Log4j2's ubiquity in Java applications and embedded products means a very large installed base. Exploitation is confirmed: the flaw is in CISA KEV (added 2023-05-01) with known ransomware use, and EPSS assigns a 100% probability of exploitation within 30 days. Do: Upgrade Log4j2 to 2.17.0 or later per vendor instructions (or 2.12.3/2.3.1 for the legacy 2.12/2.3 branches), since the 2.16.0 fix was itself incomplete in some non-default configurations. Where upgrading is not immediately possible, remove the JndiLookup class from the Log4j2 jar or disable lookup processing, and audit applications and dependencies that bundle Log4j2 while following the CISA KEV required action to apply vendor updates. | 9.0 | 100% | KEV ransomware |
| massmillions of Java deployments worldwide, with hundreds of thousands of internet-exposed services observed in public scans during the Log4Shell campaign |
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Ravie LakshmananDec 09, 2022Malware / Iranian Hackers
The subgroup of an Iranian nation-state group known as Nemesis Kitten has been attributed as behind a previously undocumented custom malware dubbed Drokbk that uses GitHub as a dead drop resolver to exfiltrate data from an infected computer, or to receive commands.
"The use of GitHub as a virtual dead drop helps the malware blend in," Secureworks principal researcher Rafe Pilling said. "All the traffic to GitHub is encrypted, meaning defensive technologies can't see what is being passed back and forth. And because GitHub is a legitimate service, it raises fewer questions."
The Iranian government-sponsored actor's malicious activities came under the radar earlier in February 2022, when it was observed exploiting Log4Shell flaws in unpatched VMware Horizon servers to deploy ransomware.
Nemesis Kitten is tracked by the larger cybersecurity community under various monikers such as TunnelVision, Cobalt Mirage, and UNC2448. It's also a sub-cluster of the Phosphorus group, with Microsoft giving it the designation DEV-0270.
It is further said to share tactical overlaps with another adversarial collective dubbed Cobalt Illusion (aka APT42), a Phosphorus subgroup that's "tasked with conducting information collection and surveillance operations against individuals and organizations of strategic interest to the Iranian government."
Subsequent investigations into the adversary's operations have uncovered two distinct intrusion sets: Cluster A, which employs BitLocker and DiskCryptor to conduct opportunistic ransomware attacks for financial gain, and Cluster B, which carries out targeted break-ins for intelligence gathering.
Microsoft, Google Mandiant, and Secureworks have since unearthed evidence tracing Cobalt Mirage's origins to two Iranian front companies Najee Technology and Afkar System that, according to the U.S. Treasury Department, are affiliated with the Islamic Revolutionary Guard Corps (IRGC).
Drokbk, the newly identified malware, is associated with Cluster B and is written in .NET. Deployed post-exploitation as a form of establishing persistence, it consists of a dropper and a payload that's used to execute commands received from a remote server.
"Early signs of its use in the wild appeared in a February 2022 intrusion at a U.S. local government network," the cybersecurity company said in a report shared with The Hacker News.
This attack entailed the compromise of a VMware Horizon server using the Log4j vulnerabilities (CVE-2021-44228 and CVE-2021-45046), ultimately leading to the delivery of the Drokbk binary by means of a compressed ZIP archive hosted on a file transfer service.
As a detection evasion measure, Drokbk employs a technique called dead drop resolver to determine its command-and-control (C2) server. The covert tactic refers to the use of an existing, legitimate external web service to host information that points to additional C2 infrastructure.
In the attack chain observed by Secureworks, this is achieved by leveraging an actor-controlled GitHub repository that contains the C2 server information within the README.md file.
"Drokbk provides the threat actors with arbitrary remote access and an additional foothold alongside tunneling tools like Fast Reverse Proxy (FRP) and Ngrok," Pilling said.
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Text extracted automatically; images, tables and formatting may be missing. Original: https://thehackernews.com/2022/12/researchers-uncover-new-drokbk-malware.html