fix: Replace broad exception handling with specific exception types

[itinance]

Summary

Replace all bare except Exception: pass blocks with specific, narrowly-scoped exception types that each decoding operation can actually raise.

Problem

The scanner uses except Exception: pass in 6 locations across the codebase — every place it attempts to decode a potentially malicious payload:

try:
    decoded = base64.b64decode(encoded).decode("utf-8", errors="replace")
    ...
except Exception:
    pass

Why this matters

except Exception catches everything — not just the expected binascii.Error or ValueError, but also:

• MemoryError — a crafted payload with an enormous decoded size would be silently ignored instead of surfacing
• RecursionError — pathological inputs could blow the stack silently
• SystemError / RuntimeError — interpreter-level issues would be swallowed
• Any unexpected bug in the scanner logic itself — typos, logic errors, or regressions would never surface

This creates a scanner evasion vector: a sufficiently creative attacker could craft a payload that triggers an unexpected exception during analysis, causing the scanner to silently skip it and report "all clear."

OWASP Reference

• A09:2021 – Security Logging and Monitoring Failures: Silent exception swallowing hides failures in security-critical detection logic, reducing the scanner's ability to identify or report threats.

Fix

Each try/except block now catches only the specific exceptions that the contained operations can raise:

Operation	Specific Exceptions
base64.b64decode()	binascii.Error, ValueError
bytes.fromhex()	ValueError
.decode("utf-8")	UnicodeDecodeError
zlib.decompress()	zlib.error
codecs.decode(_, "rot_13")	ValueError, LookupError

This also adds the missing import binascii at the top of the file.

Impact

• Any expected decoding failure (malformed base64, invalid hex, etc.) is still silently skipped — this is correct behavior since the scanner tries multiple encodings speculatively.
• Any unexpected failure (bugs, memory issues, new edge cases) will now propagate and be visible in test output, rather than being silently swallowed.

[Desperado]

Another good hardening — scanner evasion via unexpected exceptions is a real vector. Thanks!