Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
Unknown
Privileges Required
Unknown
Attack Vector
Unknown
0

CVE-2022-48629

Disclosure Date: March 05, 2024 •
CVE-2022-48629
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

In the Linux kernel, the following vulnerability has been resolved:

crypto: qcom-rng – ensure buffer for generate is completely filled

The generate function in struct rng_alg expects that the destination
buffer is completely filled if the function returns 0. qcom_rng_read()
can run into a situation where the buffer is partially filled with
randomness and the remaining part of the buffer is zeroed since
qcom_rng_generate() doesn’t check the return value. This issue can
be reproduced by running the following from libkcapi:

kcapi-rng -b 9000000 > OUTFILE

The generated OUTFILE will have three huge sections that contain all
zeros, and this is caused by the code where the test
‘val & PRNG_STATUS_DATA_AVAIL’ fails.

Let’s fix this issue by ensuring that qcom_rng_read() always returns
with a full buffer if the function returns success. Let’s also have
qcom_rng_generate() return the correct value.

Here’s some statistics from the ent project
(https://www.fourmilab.ch/random/) that shows information about the
quality of the generated numbers:

$ ent -c qcom-random-before
Value Char Occurrences Fraction
  0           606748   0.067416
  1            33104   0.003678
  2            33001   0.003667
...
253   �        32883   0.003654
254   �        33035   0.003671
255   �        33239   0.003693

Total:       9000000   1.000000

Entropy = 7.811590 bits per byte.

Optimum compression would reduce the size
of this 9000000 byte file by 2 percent.

Chi square distribution for 9000000 samples is 9329962.81, and
randomly would exceed this value less than 0.01 percent of the
times.

Arithmetic mean value of data bytes is 119.3731 (127.5 = random).
Monte Carlo value for Pi is 3.197293333 (error 1.77 percent).
Serial correlation coefficient is 0.159130 (totally uncorrelated =
0.0).

Without this patch, the results of the chi-square test is 0.01%, and
the numbers are certainly not random according to ent’s project page.
The results improve with this patch:

$ ent -c qcom-random-after
Value Char Occurrences Fraction
  0            35432   0.003937
  1            35127   0.003903
  2            35424   0.003936
...
253   �        35201   0.003911
254   �        34835   0.003871
255   �        35368   0.003930

Total:       9000000   1.000000

Entropy = 7.999979 bits per byte.

Optimum compression would reduce the size
of this 9000000 byte file by 0 percent.

Chi square distribution for 9000000 samples is 258.77, and randomly
would exceed this value 42.24 percent of the times.

Arithmetic mean value of data bytes is 127.5006 (127.5 = random).
Monte Carlo value for Pi is 3.141277333 (error 0.01 percent).
Serial correlation coefficient is 0.000468 (totally uncorrelated =
0.0).

This change was tested on a Nexus 5 phone (msm8974 SoC).

Add Assessment

No one has assessed this topic. Be the first to add your voice to the community.

CVSS V3 Severity and Metrics
Base Score:
None
Impact Score:
Unknown
Exploitability Score:
Unknown
Vector:
Unknown
Attack Vector (AV):
Unknown
Attack Complexity (AC):
Unknown
Privileges Required (PR):
Unknown
User Interaction (UI):
Unknown
Scope (S):
Unknown
Confidentiality (C):
Unknown
Integrity (I):
Unknown
Availability (A):
Unknown

General Information

Offensive Application
Unknown
Utility Class
Unknown
Ports
Unknown
OS
Unknown
Vulnerable Versions
Linux a8e32bbb96c2
Linux not down converted
Prerequisites
Unknown
Discovered By
Unknown
PoC Author
Unknown
Metasploit Module
Unknown
Reporter
Unknown

Vendors

  • Linux

Products

  • Linux
Technical Analysis