Hackers exploit Log4Shell to drop Khonsari Ransomware
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 |
Indicators of compromiseauto-extracted · verify before use · export allAll →
| Type | Indicator | Context |
|---|---|---|
| url | http://3.145.115[ | this payload as a malicious .NET binary file download from hxxp://3.145.115[.]94/zambo/groenhuyzen.exe. This is a new ransomware family, |
Full article321 words · extracted from securityaffairs.com · click to collapse
Pierluigi Paganini
December 14, 2021
Bitdefender researchers discovered that threat actors are attempting to exploit the Log4Shell flaw to deliver the new Khonsari ransomware on Windows machines.
Bitdefender researchers discovered that threat actors are attempting to exploit the Log4Shell vulnerability (CVE-2021-44228) to deliver the new Khonsari ransomware on Windows machines.
Experts warn that threat actors are attempting to exploit the Log4Shell flaw to deliver the new Khonsari ransomware on Windows machines.
The attackers exploited the Log4Shell remote code execution vulnerability to download a .NET binary from a remote server that encrypts the files on the target machine and adds the extension .khonsari to each file. The malware also drops a ransom note that requests the payment of the ransom in Bitcoin.
The ransom note is written in “C:\Users\\Desktop\HOW TO GET YOUR FILES BACK.TXT“, below is the text displayed to the victims:
“Your files have been encrypted and stolen by the Khonsari family.If you wish to decrypt , call (225) 287-1309 or email [email protected] you do not know how to buy btc, use a search engine to find exchanges.DO NOT MODIFY OR DELETE THIS FILE OR ANY ENCRYPTED FILES. IF YOU DO, YOUR FILES MAY BE UNRECOVERABLE.“
“On Sunday, 11th December, Bitdefender observed this payload as a malicious .NET binary file download from hxxp://3.145.115[.]94/zambo/groenhuyzen.exe. This is a new ransomware family, called Khonsari after the extension used on the encrypted files.” reads the analysis published by Bitdefender.
“Once executed, the malicious file will list all the drives and encrypt them entirely, except the C:\ drive. On the C:\ drive, Khonsari will encrypt only the following folders:”
C:\Users\<user>\DocumentsC:\Users\<user>\VideosC:\Users\<user>\PicturesC:\Users\<user>\DownloadsC:\Users\<user>\Desktop
The Khonsari ransomware doesn’t encrypt files with the extensions .ini and .lnk, it uses the AES 128 CBC using PaddingMode.Zeros algorithm for encryption.
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