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Showing posts with label Linux Security. Show all posts

Undetected malware attacks Linux systems

A new sophisticated, unique Linux malware dubbed HiddenWasp used in targeted attacks against victim’s who are already under attack or gone through a heavy reconnaissance.

The malware is highly sophisticated and went undetected; the malware is still active and has a zero detection rate. The malware adopted a massive amount of codes from publically available malware such as Mirai and the Azazel rootkit.

Unlike Windows malware, Linux malware authors won’t concentrate much with evasion techniques, as the trend of using Anti-Virus solutions in Linux machine is very less when compared to other platforms.

However, the Intezer report shows “malware with strong evasion techniques does exist for the Linux platform. There is also a high ratio of publicly available open-source malware that utilizes strong evasion techniques and can be easily adapted by attackers.” In the past, we saw many malware focussed on crypto-mining or DDoS activity, but the HiddenWasp is purely a targeted remote control attack.

The malware is composed of a user-mode rootkit, a trojan, and an initial deployment script. Researchers spotted the files went undetected in VirusTotal and the malware hosted in servers of a hosting company ThinkDream located in Hong Kong.

While analyzing scripts, Intezer spotted a user named ‘sftp’ and hardcodes, which can be used for initial compromise and also the scripts has variable to clear the older versions from the compromised systems.

The scripts also include variables to determine server architecture of the compromised system and download components from the malicious server based on the compromised server architecture. Once the components installed, the trojan will get executed on the system.

“Within this script, we were able to observe that the main implants were downloaded in the form of tarballs. As previously mentioned, each tarball contains the main trojan, the rootkit, and a deployment script for x86 and x86_64 builds accordingly.”

Unpatched Linux Kernel Vulnerabilities Could Be Exploited For Local Dos

As of late two denial-of-service (DoS) vulnerabilities evaluated as ones with Medium severity, affected the Linux kernel 4.19.2 in addition to its previous versions. The two defects are NULL pointer deference issues that can be misused by even a local attacker if he or she wishes to trigger a DoS condition.

Tracked as CVE-2018-19406, the primary issue was observed to dwell in a Linux kernel function called kvm_pv_send_ipi, which is characterized in curve/x86/kvm/lapic.c. The defect is activated when the Advanced Programmable Interrupt Controller (APIC) delineate is not initialized correctly.
To abuse the security defect, a local attacker can utilize the already 'crafted' system calls to achieve a circumstance where the apic delineate remains uninitialized.

In a published blog post the Linux contributor Wanpeng Li reports:
“The reason is that the apic map has not yet been initialized, the testcase triggers pv_send_ipi interface by vmcall which results in kvm->arch.apic_map is dereferenced”

The second vulnerability, which has been doled out the CVE number CVE-2018-19407, impacts the vcpu_scan_ioapic function that is characterized in curve/x86/kvm/x86.c. The bug is activated when I/O Advanced Programmable Interrupt Controller (I/O APIC) does not instate effectively.

Further adds the security advisor “the vcpu_scan_ioapic function in arch/x86/kvm/x86.c in the Linux kernel through 4.19.2 allows local users to cause a denial of service (NULL pointer dereference and BUG) via crafted system calls that reach a situation where ioapic is uninitialized.”

“The reason is that the testcase writes hyperv synic HV_X64_MSR_SINT6 msr and triggers scan ioapic logic to load synic vectors into EOI exit bitmap. However, irqchip is not initialized by this simple testcase, ioapic/apic objects should not be accessed,” reads the analysis published by Wanpeng Li.

Albeit informal patches for the two blemishes were discharged in the informal Linux Kernel Mailing List (LKML) archive, however despite everything they haven't been pushed upstream.

Bug in GnuTLS allows hackers to run malicious code in Your Linux

Another major security vulnerability has been discovered in the popular cryptographic Library 'GnuTLS' that leaves Linux vulnerable to remote code execution.

GNUTLS is a free library implementing Secure Socket Layer(SSL), Transport Layer Security (TLS) and Datagram Transport Layer Security(DTLS) protocols which are used to offer secure communications.
"A flaw was found in the way GnuTLS parsed session ids from Server Hello packets of the TLS/SSL handshake." an entry posted on the Red Hat Bug Tracker reads.

Flaw: The read_server_hello function checks only whether the length of the Session ID does not exceed incoming packet size but it fails to ensure it doesn't exceed maximum length of Session ID.

A malicious server could exploit this vulnerability by sending a very long Session ID value and run a malicious code in "a connecting TLS/SSL client using GnuTLS".

In March, a different vulnerability was patched in GnuTLS Library that could have allowed attackers "to create a specially crafted certificate that could be accepted by GnuTLS as valid for a site chosen by the attacker"

I've updated my Linux, Did you?

Update your Ubuntu 12.10 to fix the Linux Kernel vulnerabilities

Canonical on May 2 released security advisory to fix ten Linux kernel vulnerabilities that affect the Ubuntu 12.10 version. 

The list of vulnerabilities include Information leak in the Linux kernel's UDFfile system implementation ((CVE-2012-6548), Information leak in the Linux kernel's ISO9660 CDROM file system driver(CVE-2012-6549), Integer overflow in the Direct Rendering Manager (DRM), subsystem for the i915 video driver in the Linux kernel(CVE-2013-0913), Denial of service flaw in guest OS time updates in the Linuxkernel's KVM((CVE-2013-1796)).

Other vulnerabilities are Use after free error in guest OS time updates in the Linux kernel;s KVM (CVE-2013-1797), Flaw in the way KVM emulated the IOAPIC (CVE-2013-1798), Escalate privileges vulnerability in the Linux kernel's ext3 filesystem(CVE-2013-1848) , Buffer overflow was discovered in the Linux Kernel's USB subsystem for devices reporting the cdc-wdm class (CVE-2013-1860), information leak in the Linux kernel's dcb netlink interface (CVE-2013-2634) ,kernel stack information leak in the RTNETLINK component(CVE-2013-2635).

To patch these vulnerabilities, Ubuntu users are urged to update your system to the following package version: linux-image-3.5.0-28-generic 3.5.0-28.48 .

To update your system, please follow these instructions: