CVE Vulnerabilities

CVE-2021-22791

Out-of-bounds Write

Published: Sep 02, 2021 | Modified: Sep 13, 2021
CVSS 3.x
6.5
MEDIUM
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS 2.x
4 MEDIUM
AV:N/AC:L/Au:S/C:N/I:N/A:P
RedHat/V2
RedHat/V3
Ubuntu

A CWE-787: Out-of-bounds Write vulnerability that could cause a Denial of Service on the Modicon PLC controller / simulator when updating the controller application with a specially crafted project file exists in Modicon M580 CPU (part numbers BMEP* and BMEH*, all versions), Modicon M340 CPU (part numbers BMXP34*, all versions), Modicon MC80 (part numbers BMKC80*, all versions), Modicon Momentum Ethernet CPU (part numbers 171CBU*, all versions), PLC Simulator for EcoStruxureª Control Expert, including all Unity Pro versions (former name of EcoStruxureª Control Expert, all versions), PLC Simulator for EcoStruxureª Process Expert including all HDCS versions (former name of EcoStruxureª Process Expert, all versions), Modicon Quantum CPU (part numbers 140CPU*, all versions), Modicon Premium CPU (part numbers TSXP5*, all versions).

Weakness

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

Affected Software

Name Vendor Start Version End Version
Modicon_m340_bmxp341000 Schneider-electric - -
Modicon_m340_bmxp342010 Schneider-electric - -
Modicon_m340_bmxp342020 Schneider-electric - -
Modicon_m340_bmxp342030 Schneider-electric - -
Modicon_m580_bmeh582040 Schneider-electric - -
Modicon_m580_bmeh582040c Schneider-electric - -
Modicon_m580_bmeh582040s Schneider-electric - -
Modicon_m580_bmeh584040 Schneider-electric - -
Modicon_m580_bmeh584040c Schneider-electric - -
Modicon_m580_bmeh584040s Schneider-electric - -
Modicon_m580_bmeh586040 Schneider-electric - -
Modicon_m580_bmeh586040c Schneider-electric - -
Modicon_m580_bmeh586040s Schneider-electric - -
Modicon_m580_bmep581020 Schneider-electric - -
Modicon_m580_bmep581020h Schneider-electric - -
Modicon_m580_bmep582020 Schneider-electric - -
Modicon_m580_bmep582020h Schneider-electric - -
Modicon_m580_bmep582040 Schneider-electric - -
Modicon_m580_bmep582040h Schneider-electric - -
Modicon_m580_bmep582040s Schneider-electric - -
Modicon_m580_bmep583020 Schneider-electric - -
Modicon_m580_bmep583040 Schneider-electric - -
Modicon_m580_bmep584020 Schneider-electric - -
Modicon_m580_bmep584040 Schneider-electric - -
Modicon_m580_bmep584040s Schneider-electric - -
Modicon_m580_bmep585040 Schneider-electric - -
Modicon_m580_bmep585040c Schneider-electric - -
Modicon_m580_bmep586040 Schneider-electric - -
Modicon_m580_bmep586040c Schneider-electric - -
Modicon_mc80_bmkc8020301 Schneider-electric - -
Modicon_mc80_bmkc8020310 Schneider-electric - -
Modicon_mc80_bmkc8030311 Schneider-electric - -
Modicon_momentum_171cbu78090 Schneider-electric - -
Modicon_momentum_171cbu98090 Schneider-electric - -
Modicon_momentum_171cbu98091 Schneider-electric - -
Modicon_premium_tsxp57_1634m Schneider-electric - -
Modicon_premium_tsxp57_2634m Schneider-electric - -
Modicon_premium_tsxp57_2834m Schneider-electric - -
Modicon_premium_tsxp57_454m Schneider-electric - -
Modicon_premium_tsxp57_4634m Schneider-electric - -
Modicon_premium_tsxp57_554m Schneider-electric - -
Modicon_premium_tsxp57_5634m Schneider-electric - -
Modicon_premium_tsxp57_6634m Schneider-electric - -
Modicon_quantum_140cpu65150 Schneider-electric - -
Modicon_quantum_140cpu65150c Schneider-electric - -
Modicon_quantum_140cpu65160 Schneider-electric - -
Modicon_quantum_140cpu65160c Schneider-electric - -
Plc_simulator_for_ecostruxure_control_expert Schneider-electric - -
Plc_simulator_for_ecostruxure_process_expert Schneider-electric - -

Potential Mitigations

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

  • For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer.

  • Be wary that a language’s interface to native code may still be subject to overflows, even if the language itself is theoretically safe.

  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

  • Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions.

  • Run or compile the software using features or extensions that automatically provide a protection mechanism that mitigates or eliminates buffer overflows.

  • For example, certain compilers and extensions provide automatic buffer overflow detection mechanisms that are built into the compiled code. Examples include the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice.

  • Consider adhering to the following rules when allocating and managing an application’s memory:

  • Run or compile the software using features or extensions that randomly arrange the positions of a program’s executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.

  • Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64].

References