peass-ng/PEASS-ng · error · ArgumentNullException

str

Error message

str

What it means

This obsolete byte-array constructor of DerBmpString throws ArgumentNullException when the caller passes a null byte array; it fires at the very first guard of the constructor before any encoding length checks, meaning the code constructed a BMP string from a null buffer.

Source

Thrown at winPEAS/winPEASexe/winPEAS/3rdParty/BouncyCastle/asn1/DerBmpString.cs:61

        {
            Asn1Object o = obj.GetObject();

            if (isExplicit || o is DerBmpString)
            {
                return GetInstance(o);
            }

            return new DerBmpString(Asn1OctetString.GetInstance(o).GetOctets());
        }

        /**
         * basic constructor - byte encoded string.
         */
        [Obsolete("Will become internal")]
        public DerBmpString(byte[] str)
        {
            if (str == null)
                throw new ArgumentNullException("str");

            int byteLen = str.Length;
            if (0 != (byteLen & 1))
                throw new ArgumentException("malformed BMPString encoding encountered", "str");

            int charLen = byteLen / 2;
            char[] cs = new char[charLen];

            for (int i = 0; i != charLen; i++)
            {
                cs[i] = (char)((str[2 * i] << 8) | (str[2 * i + 1] & 0xff));
            }

            this.str = new string(cs);
        }

        internal DerBmpString(char[] str)
        {

View on GitHub (pinned to 53fb989abc)

Solutions

1. Pass a non-null byte[]; use Array.Empty<byte>() if there is genuinely no content.
2. Construct from a string instead: new DerBmpString("text") handles encoding for you.
3. Fix the upstream producer that returned null and handle its failure case.

Example fix

// before
var bmp = new DerBmpString(GetEncodedName()); // may return null
// after
byte[] enc = GetEncodedName() ?? Array.Empty<byte>();
var bmp = new DerBmpString(enc);

if (str == null) throw new InvalidOperationException("BMPString byte content missing");

static bool HasBmpBytes(byte[] b) => b != null;

When it happens

Trigger: Calling new DerBmpString((byte[])null) — e.g. passing the result of a failed encode or a null field extracted from a structure.

Common situations: Bridge code converting strings to bytes where the string was null; decoding pipelines that propagate null instead of empty arrays.

Related errors

• data
• must be in the range 0 to 7
• if 'data' is empty, 'padBits' must be 0
• attempt to get non-octet aligned data from BIT STRING
• truncated BIT STRING detected

AI-assisted analysis of peass-ng/PEASS-ng@53fb989abc (2026-09-02). Data as JSON: /api/errors/2eda17a3994fb03e. Report an issue: GitHub.