Quantum Secular Labs / Blog / Advisories

CVE-2018-8786: Freerdp: Buffer overflow

CVE-2018-8786 is rated critical with a CVSS v3.1 base score of 9.8 and affects Freerdp, along with 9 other products in NVD’s configuration data. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.

Vulnerability description

FreeRDP prior to version 2.0.0-rc4 contains an Integer Truncation that leads to a Heap-Based Buffer Overflow in function update_read_bitmap_update() and results in a memory corruption and probably even a remote code execution.

Severity breakdown

CVSS v3.1 9.8: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
  • Attack complexity: Low. No special conditions; the attack can be repeated reliably.
  • Privileges required: None. No account or prior access is needed.
  • User interaction: None. No action from any user is needed.
  • Scope: Unchanged. Impact stays within the vulnerable component.
  • Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
  • Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
  • Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-680: Integer Overflow to Buffer Overflow

The product performs a calculation to determine how much memory to allocate, but an integer overflow can occur that causes less memory to be allocated than expected, leading to a buffer overflow.

CWE-681: Incorrect Conversion between Numeric Types

When converting from one data type to another, such as long to integer, data can be omitted or translated in a way that produces unexpected values. If the resulting values are used in a sensitive context, then dangerous behaviors may occur.

CWE-787: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

Affected products

  • Freerdp: up to and including 1.2.0; 2.0.0 rc1; 2.0.0 rc2; 2.0.0 rc3
  • Canonical Ubuntu Linux: 14.04; 16.04; 18.04; 18.10
  • Debian Linux: 8.0
  • Fedoraproject: 28
  • Red Hat Enterprise Linux Desktop: 7.0
  • Red Hat Enterprise Linux Server: 7.0
  • Red Hat Enterprise Linux Server Aus: 7.6
  • Red Hat Enterprise Linux Server Eus: 7.6
  • Red Hat Enterprise Linux Server Tus: 7.6
  • Red Hat Enterprise Linux Workstation: 7.0

References