Jan 19 2024

CISA: Critical Ivanti auth bypass bug now actively exploited

Category: CISA — disc7 @ 7:03 am
https://www.bleepingcomputer.com/news/security/cisa-critical-ivanti-auth-bypass-bug-now-actively-exploited/

CISA warns that a critical authentication bypass vulnerability in Ivanti’s Endpoint Manager Mobile (EPMM) and MobileIron Core device management software (patched in August 2023) is now under active exploitation.

Tracked as CVE-2023-35082, the flaw is a remote unauthenticated API access vulnerability affecting all versions of EPMM 11.10, 11.9, and 11.8 and MobileIron Core 11.7 and below,.

Successful exploitation provides attackers access to personally identifiable information (PII) of mobile device users and can let them backdoor compromised servers when chaining the bug with other flaws.

“Ivanti has an RPM script available now. We recommend customers first upgrade to a supported version and then apply the RPM script,” the company said in August. “More detailed information can be found in this Knowledge Base articleon the Ivanti Community portal.”

Cybersecurity company Rapid7, which discovered and reported the vulnerability, provides indicators of compromise(IOCs) to help admins detect signs of a CVE-2023-35082 attack.

According to Shodan, 6,300 Ivanti EPMM user portals are currently exposed online, while the Shadowserver threat monitoring platform tracks 3,420 Internet-exposed EPMM appliances.

Shodan’s data also reveals that the more than 150 instances linked to government agencies worldwide can be directly accessed via the Internet.

Internet-exposed Ivanti EPMM user portals
Internet-exposed Ivanti EPMM user portals (Shodan)

​While it has yet to provide further details on CVE-2023-35082 active exploitation, CISA added the vulnerability to its Known Exploited Vulnerabilities Catalog based on evidence of active exploitation and says there’s no evidence of abuse in ransomware attacks.

The cybersecurity agency also ordered U.S. federal agencies to patch it by February 2, as required by a binding operational directive (BOD 22-01) issued three years ago.

Ivanti has yet to update its August advisories or issue another notification warning that attackers are using this security vulnerability in the wild.

Two other Ivanti Connect Secure (ICS) zero-days, an auth bypass (CVE-2023-46805) and a command injection (CVE-2024-21887) are now also under mass exploitation by multiple threat groups, starting January 11.

Victims compromised so far range from small businesses to multiple Fortune 500 companies from various industry sectors, with the attackers having already backdoored over 1,700 ICS VPN appliances using a GIFTEDVISITOR webshell variant.

Multiple other Ivanti zero-days (i.e., CVE-2021-22893, CVE-2023-35078, CVE-2023-35081, CVE-2023-38035) have been exploited in recent years to breach dozens of government, defense, and financial organizations across the United States and Europe, several Norwegian government organizations, as well as in targeted attacks.

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Tags: Antivirus Bypass Techniques, Ivanti auth bypass bug

Dec 29 2022

GuLoader Malware Uses Advanced Anti-Analysis Techniques to Evade Detection

Category: Antivirus,Malware,Threat detection — DISC @ 11:30 am
GuLoader Malware Uses Advanced Anti-Analysis Techniques to Evade Detection

An advanced malware downloader named GuLoader has recently been exposed by cybersecurity researchers at CrowdStrike. This advanced downloader has the capability to evade the detection of security software by adopting a variety of techniques.

While analyzing the shellcode of GuLoader, a brand-new anti-analysis technique was discovered by CrowdStrike through which researchers would be able to identify if the malware is operating in an adversarial environment or not. While this is done by examining the whole process memory for any VM-related strings.

Evolution of GuLoader Malware

On infected machines, GuLoader (aka CloudEyE) distributes remote access trojans like AgentTesla, FormBook, Nanocore, NETWIRE, Remcos, and the Parallax RAT using the VBS downloader. 

GuLoader has been active since at least 2019 and has undergone several changes in its functionality and delivery methods. Over time, the malware has become more sophisticated, using various methods to evade detection and avoid being removed from infected systems. 

It has also been distributed through other channels, such as exploit kits and hacked websites. While it has evolved over time and has been used in various campaigns to deliver a range of malware, including ransomware, banking Trojans, and other types of malware.

A strong anti-analysis technique was also deployed by GuLoader in order to avoid detection in order to remain undetected. 

GuLoader exhibits a three-stage process, the VBScript script will first inject the shellcode embedded within it into the memory, then the next stage of the process will execute anti-analysis checks that will protect the code from being analyzed.

Furthermore, the shellcode also incorporates the same anti-analysis methods in order to avoid detection by third parties. It is through this shellcode that an attacker is able to download a final payload of their choice and execute it with the same anti-analysis methods as the original shellcode on the host that is compromised.

Detecting breakpoints used for code analysis is done with anti-debugging and anti-disassembling checks in the malware.

There is also a redundant code injection mechanism that can be used to avoid the use of a NTDLL.dll hook that is commonly used by antivirus programs and EDRs.

In order to detect and flag processes on Windows that may be suspicious, anti-malware engines use NTDLL.dll API hooking. 

Anti-Analysis Techniques

Here below we have mentioned the anti-analysis techniques used:-

  • Anti-Debugging
  • Anti-Virtual Machine
  • Process Hollowing

It was pointed out by experts that GuLoader remains a treacherous threat that is constantly evolving as it continues to develop. Furthermore, experts also provided indicators of compromise for the latest version of the downloader, as well as other key information.

GuLoader Malware Advanced Anti-Analysis

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Tags: Antivirus Bypass Techniques, Evade Detection, Malware