Daily Archives: September 19, 2023

News

Exploring Winrar Vulnerability (CVE-2023-38831)

Read Time:5 Minute, 9 Second

Authored by Neil Tyagi

On 23 August 2023, NIST disclosed a critical RCE vulnerability CVE-2023-38831. It is related to an RCE vulnerability in WinRAR before version 6.23. The issue occurs because a ZIP archive may include a benign file (such as an ordinary .JPG file) and also a folder that has the same name as the harmless file, and the contents of the folder (which may include executable content) are processed during an attempt to access only the benign file.

Our intelligence shows that this vulnerability is being exploited as early as April 2023. Let’s look at a sample exploiting this vulnerability (Hash: bc15b0264244339c002f83e639c328367efb1d7de1b3b7c483a2e2558b115eaa)

The image below shows that the archive is named trading_system, which hints that it is used to target traders

We can also see that the threat actor can craft the archive so that folder and file names are the same.
This is interesting as Windows doesn’t allow files and folders to have the same name in the same path.
This shows that it was weaponized after creating a regular zip by changing the bytes to make the file and folder name the same.
Also, note there is a trailing space at the end of the file and folder name (in yellow).
When we look inside the folder, we see many files, but the most important file is highlighted, which is a bat file containing a malicious script.
The bat file also has the same name as the benign file outside the folder.

When we check the script, we see it launches cmd in the minimized state, then goes to the temp folder where WinRAR will extract the files, then tries to find the weakicons.com file, which is present inside the folder and executes it using wmic and then exits.
Checking weakicons.com we find that it is a CAB SFX file.
We extract it to check what is inside.

We found a PE file, some ActiveX control objects, and two text files.
AMD.exe is a visual basic compiled file whose main job is to extract the dll hidden in a blob of data inside pc.txt and execute the ActiveX controls.
Inside add.txt, we find the registry keys it will try to manipulate

The first control is responsible for registering a COM object in Windows. During registration, registry keys are imported from the “add.txt” file. As a result, a specific COM object with a unique CLSID is registered in the infected system. The default value of the InprocServer32 key is populated with the path to a malicious DLL named “Core.ocx”.

Wmic process executes weakicons.com

com executes AMD.exe

AMD.exe extracts the encrypted dll file inside pc.txt and writes it in the romaingnvidia folder.

Here, we observe AMD.exe calls reg.exe on registry keys inside add.txt

Timeout is also called to slow down the activities of the infection chain.

AMD.exe Calls rundll32 on the clsid that is registered in the registry

We can see successful tcp connection to threat actors C2.( ip 37[.]120[.]158[.]229)

Global Heatmap where this vulnerability is being seen in the wild(based on McAfee telemetry data)

Infection chain

How does the vulnerability work?

Here, we will analyze the issue causing WinRAR to execute the script instead of opening the image.
We will compare how WinRAR behaves when we execute an image file from a weaponized zip vs. a normal zip. So we fire up ProcMon First.

Normal.zip

Weaponized.zip

The above image shows that the first logical bug is how WinRAR is extracting files in the temp folder before executing them. In the case of a regular zip, only the clean image file is extracted to the temp folder, whereas in the case of a weaponized zip, even the files present inside the folder are extracted to the temp folder along with the clean image file. This is due to the same file names we have given, which makes WinRAR extract those in temp.
Verifying the same in the temp folder

Normal Zip

Weaponized Zip

In Logs, when we dig deep, we can see Winrar searches for our filename with an *, which causes it to iterate over our bat file as it has the same name, which in turn gets executed.

To see what’s happening under the hood, we hook a debugger and launch WinRAR by manipulating the “image file Execution options” registry key.

When we execute the rar file, we see the debugger getting attached to the winrar process so that we can do just-in-time debugging.
We put a breakpoint on the ShellExecuteExW function to see what parameters are passed to it just after clicking the jpeg file.
When we double-click on the image file, we can see the debugger is opened, and after a few clicks, we hit our breakpoint.

Normal zip

In this case, the correct parameter is passed to the ShellExecuteExW function as the file exists at this exact path.

Weaponized zip

In this case, an incorrect parameter is passed to the ShellExecuteExW function as the parameter contains a trailing space, and such a file does not exist on the disk.

When we dig deep, we find that later, it calls PathUnquoteSpacesA API call, as per MSDN. It “Removes quotes from the beginning and end of a path.”
As quotes are removed from the end of the path, ShellExecuteExW executes “simple_image.jpg .cmd” instead of “simple_image.jpg.”

IOC’s

Sha256
Detection

bc15b0264244339c002f83e639c328367efb1d7de1b3b7c483a2e2558b115eaa
Trojan:Archive/2023_38831.NEAA

 

 

.( ip 37[.]120[.]158[.]229)
REG keys

File path

%APPDATA%NvidiaCore.ocx

Recommendations

WinRAR users should immediately update to the latest version. WinRAR archiver, a powerful tool to process RAR and ZIP files (rarlab.com)
Use a licensed and updated McAfee+ subscription to stay protected.
Stay informed about common cyber threats and tactics used by cybercriminals. This knowledge can help you recognize potential risks and avoid scams.
Be very cautious when dealing with attachments from unknown sources. Only run attachments that come from trusted sources.
Protect your accounts by using multi-factor authentication.

The post Exploring Winrar Vulnerability (CVE-2023-38831) appeared first on McAfee Blog.

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Advisories

USN-6385-1: Linux kernel (OEM) vulnerabilities

Read Time:8 Minute, 8 Second

It was discovered that some AMD x86-64 processors with SMT enabled could
speculatively execute instructions using a return address from a sibling
thread. A local attacker could possibly use this to expose sensitive
information. (CVE-2022-27672)

William Zhao discovered that the Traffic Control (TC) subsystem in the
Linux kernel did not properly handle network packet retransmission in
certain situations. A local attacker could use this to cause a denial of
service (kernel deadlock). (CVE-2022-4269)

Jordy Zomer and Alexandra Sandulescu discovered that syscalls invoking the
do_prlimit() function in the Linux kernel did not properly handle
speculative execution barriers. A local attacker could use this to expose
sensitive information (kernel memory). (CVE-2023-0458)

It was discovered that the TLS subsystem in the Linux kernel contained a
type confusion vulnerability in some situations. A local attacker could use
this to cause a denial of service (system crash) or possibly expose
sensitive information. (CVE-2023-1075)

It was discovered that the TUN/TAP driver in the Linux kernel did not
properly initialize socket data. A local attacker could use this to cause a
denial of service (system crash). (CVE-2023-1076, CVE-2023-4194)

It was discovered that the IPv6 implementation in the Linux kernel
contained a high rate of hash collisions in connection lookup table. A
remote attacker could use this to cause a denial of service (excessive CPU
consumption). (CVE-2023-1206)

It was discovered that the Broadcom FullMAC USB WiFi driver in the Linux
kernel did not properly perform data buffer size validation in some
situations. A physically proximate attacker could use this to craft a
malicious USB device that when inserted, could cause a denial of service
(system crash) or possibly expose sensitive information. (CVE-2023-1380)

It was discovered that a race condition existed in the btrfs file system
implementation in the Linux kernel, leading to a use-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly expose sensitive information. (CVE-2023-1611)

Ruihan Li discovered that the bluetooth subsystem in the Linux kernel did
not properly perform permissions checks when handling HCI sockets. A
physically proximate attacker could use this to cause a denial of service
(bluetooth communication). (CVE-2023-2002)

Tavis Ormandy discovered that some AMD processors did not properly handle
speculative execution of certain vector register instructions. A local
attacker could use this to expose sensitive information. (CVE-2023-20593)

It was discovered that a use-after-free vulnerability existed in the iSCSI
TCP implementation in the Linux kernel. A local attacker could possibly use
this to cause a denial of service (system crash). (CVE-2023-2162)

Juan Jose Lopez Jaimez, Meador Inge, Simon Scannell, and Nenad Stojanovski
discovered that the BPF verifier in the Linux kernel did not properly mark
registers for precision tracking in certain situations, leading to an out-
of-bounds access vulnerability. A local attacker could use this to cause a
denial of service (system crash) or possibly execute arbitrary code.
(CVE-2023-2163)

It was discovered that the perf subsystem in the Linux kernel contained a
use-after-free vulnerability. A privileged local attacker could possibly
use this to cause a denial of service (system crash) or possibly execute
arbitrary code. (CVE-2023-2235)

Zheng Zhang discovered that the device-mapper implementation in the Linux
kernel did not properly handle locking during table_clear() operations. A
local attacker could use this to cause a denial of service (kernel
deadlock). (CVE-2023-2269)

Wei Chen discovered that the DVB USB AZ6027 driver in the Linux kernel
contained a null pointer dereference when handling certain messages from
user space. A local attacker could use this to cause a denial of service
(system crash). (CVE-2023-28328)

It was discovered that a race condition existed in the TLS subsystem in the
Linux kernel, leading to a use-after-free or a null pointer dereference
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2023-28466)

It was discovered that a race condition existed in the f2fs file system in
the Linux kernel, leading to a null pointer dereference vulnerability. An
attacker could use this to construct a malicious f2fs image that, when
mounted and operated on, could cause a denial of service (system crash).
(CVE-2023-2898)

It was discovered that the IP-VLAN network driver for the Linux kernel did
not properly initialize memory in some situations, leading to an out-of-
bounds write vulnerability. An attacker could use this to cause a denial of
service (system crash) or possibly execute arbitrary code. (CVE-2023-3090)

It was discovered that the Ricoh R5C592 MemoryStick card reader driver in
the Linux kernel contained a race condition during module unload, leading
to a use-after-free vulnerability. A local attacker could use this to cause
a denial of service (system crash) or possibly execute arbitrary code.
(CVE-2023-3141)

Gwangun Jung discovered that the Quick Fair Queueing scheduler
implementation in the Linux kernel contained an out-of-bounds write
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2023-31436)

It was discovered that the Qualcomm MSM DPU driver in the Linux kernel did
not properly validate memory allocations in certain situations, leading to
a null pointer dereference vulnerability. A local attacker could use this
to cause a denial of service (system crash). (CVE-2023-3220)

It was discovered that the NET/ROM protocol implementation in the Linux
kernel contained a race condition in some situations, leading to a use-
after-free vulnerability. A local attacker could use this to cause a denial
of service (system crash) or possibly execute arbitrary code.
(CVE-2023-32269)

It was discovered that the netfilter subsystem in the Linux kernel did not
properly handle some error conditions, leading to a use-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2023-3390)

It was discovered that the universal 32bit network packet classifier
implementation in the Linux kernel did not properly perform reference
counting in some situations, leading to a use-after-free vulnerability. A
local attacker could use this to cause a denial of service (system crash)
or possibly execute arbitrary code. (CVE-2023-3609)

It was discovered that the netfilter subsystem in the Linux kernel did not
properly handle certain error conditions, leading to a use-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2023-3610)

It was discovered that the Quick Fair Queueing network scheduler
implementation in the Linux kernel contained an out-of-bounds write
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2023-3611)

It was discovered that the network packet classifier with
netfilter/firewall marks implementation in the Linux kernel did not
properly handle reference counting, leading to a use-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2023-3776)

Kevin Rich discovered that the netfilter subsystem in the Linux kernel did
not properly handle table rules flush in certain circumstances. A local
attacker could possibly use this to cause a denial of service (system
crash) or execute arbitrary code. (CVE-2023-3777)

It was discovered that the NFC implementation in the Linux kernel contained
a use-after-free vulnerability when performing peer-to-peer communication
in certain conditions. A privileged attacker could use this to cause a
denial of service (system crash) or possibly expose sensitive information
(kernel memory). (CVE-2023-3863)

Kevin Rich discovered that the netfilter subsystem in the Linux kernel did
not properly handle rule additions to bound chains in certain
circumstances. A local attacker could possibly use this to cause a denial
of service (system crash) or execute arbitrary code. (CVE-2023-3995)

It was discovered that the netfilter subsystem in the Linux kernel did not
properly handle PIPAPO element removal, leading to a use-after-free
vulnerability. A local attacker could possibly use this to cause a denial
of service (system crash) or execute arbitrary code. (CVE-2023-4004)

Kevin Rich discovered that the netfilter subsystem in the Linux kernel did
not properly handle bound chain deactivation in certain circumstances. A
local attacker could possibly use this to cause a denial of service (system
crash) or execute arbitrary code. (CVE-2023-4015)

It was discovered that the bluetooth subsystem in the Linux kernel did not
properly handle L2CAP socket release, leading to a use-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2023-40283)

It was discovered that some network classifier implementations in the Linux
kernel contained use-after-free vulnerabilities. A local attacker could use
this to cause a denial of service (system crash) or possibly execute
arbitrary code. (CVE-2023-4128)

Maxim Suhanov discovered that the exFAT file system implementation in the
Linux kernel did not properly check a file name length, leading to an out-
of-bounds write vulnerability. An attacker could use this to construct a
malicious exFAT image that, when mounted and operated on, could cause a
denial of service (system crash) or possibly execute arbitrary code.
(CVE-2023-4273)

Lonial Con discovered that the netfilter subsystem in the Linux kernel
contained a memory leak when handling certain element flush operations. A
local attacker could use this to expose sensitive information (kernel
memory). (CVE-2023-4569)

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Advisories

USN-6384-1: Linux kernel (OEM) vulnerabilities

Read Time:23 Second

Jana Hofmann, Emanuele Vannacci, Cedric Fournet, Boris Kopf, and Oleksii
Oleksenko discovered that some AMD processors could leak stale data from
division operations in certain situations. A local attacker could possibly
use this to expose sensitive information. (CVE-2023-20588)

Lonial Con discovered that the netfilter subsystem in the Linux kernel
contained a memory leak when handling certain element flush operations. A
local attacker could use this to expose sensitive information (kernel
memory). (CVE-2023-4569)

Read More

Advisories

USN-6383-1: Linux kernel vulnerabilities

Read Time:1 Minute, 0 Second

Jana Hofmann, Emanuele Vannacci, Cedric Fournet, Boris Kopf, and Oleksii
Oleksenko discovered that some AMD processors could leak stale data from
division operations in certain situations. A local attacker could possibly
use this to expose sensitive information. (CVE-2023-20588)

It was discovered that the ARM64 KVM implementation in the Linux kernel did
not properly restrict hypervisor memory access. An attacker in a guest VM
could use this to execute arbitrary code in the host OS. (CVE-2023-21264)

It was discovered that the bluetooth subsystem in the Linux kernel did not
properly handle L2CAP socket release, leading to a use-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2023-40283)

It was discovered that some network classifier implementations in the Linux
kernel contained use-after-free vulnerabilities. A local attacker could use
this to cause a denial of service (system crash) or possibly execute
arbitrary code. (CVE-2023-4128)

Lonial Con discovered that the netfilter subsystem in the Linux kernel
contained a memory leak when handling certain element flush operations. A
local attacker could use this to expose sensitive information (kernel
memory). (CVE-2023-4569)

Read More

Advisories

CVE-2022-47555

Read Time:10 Second

** UNSUPPPORTED WHEN ASSIGNED ** Operating system command injection in ekorCCP and ekorRCI, which could allow an authenticated attacker to execute commands, create new users with elevated privileges or set up a backdoor.

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Advisories

CVE-2022-47554

Read Time:11 Second

** UNSUPPPORTED WHEN ASSIGNED ** Exposure of sensitive information in ekorCCP and ekorRCI, potentially allowing a remote attacker to obtain critical information from various .xml files, including .xml files containing credentials, without being authenticated within the web server.

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