CWE-1335: Incorrect Bitwise Shift of Integer | Glexia
CWE-1335 (Incorrect Bitwise Shift of Integer) weakness overview with consequences, detection methods, mitigations, related CVEs and MITRE ATT&CK context.
Glexia's Take · Automated analysis
CWE-1335: Incorrect Bitwise Shift of Integer
Incorrect Bitwise Shift of Integer represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Integrity: DoS: Crash, Exit, or Restart
Developer Pattern
CWE-1335 is the kind of defect developers can usually prevent with explicit validation, safer framework defaults, and tests that exercise hostile input or unsafe state transitions.
Automation confidence
high confidence from CWE-1335, 4.20.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Official CWE Definition
CWE-1335: Incorrect Bitwise Shift of Integer
An integer value is specified to be shifted by a negative amount or an amount greater than or equal to the number of bits contained in the value causing an unexpected or indeterminate result.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- A negative shift amount for an x86 or x86_64 shift instruction will produce the number of bits to be shifted by taking a 2's-complement of the shift amount and effectively masking that amount to the lowest 6 bits for a 64 bit shift instruction. The example above ends up with a shift amount of -5. The hexadecimal value is FFFFFFFFFFFFFFFD which, when bits above the 6th bit are masked off, the shift amount becomes a binary shift value of 111101 which is 61 decimal. A shift of 61 produces a very different result than -5. The previous example is a very simple version of the following code which is probably more realistic of what happens in a real system.,Note that the good example not only checks for negative shifts and disallows them, but it also checks for over-shifts. No bit operation is done if the shift is out of bounds. Depending on the program, perhaps an error message should be logged.
Remediation
- Implementation: Implicitly or explicitly add checks and mitigation for negative or over-shift values.
Detection
- Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Mappings
Related CVEs, CWEs, and ATT&CK context
Related CWEs
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.