X-OVH-SPAMCAUSE decoder

spam_decode.py

def decode(msg):
    text = []
    for i in range(0, len(msg), 2):
        text.append(unrot(msg[i: i + 2]))
    return str.join('', text)


def unrot(pair, key=ord('x')):
    offset = 0
    for c in 'cdefgh':
        if c in pair:
            offset = (ord('g') - ord(c)) * 16
            break
    return chr(sum(ord(c) for c in pair) - key - offset)

  
if __name__ == '__main__':
    import sys
    print(decode(sys.argv[1]))

yes thanks a lot it works fine !

Just to know, is it normal that the result is truncated
Thanks again

Can you provide an example? In principle, the entire spamcause string is parsed and decoded.

is there any updte for this vad decoder? it cannot decrypt this
X-Spamcause: 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

is there any updte for this vad decoder? it cannot decrypt this X-Spamcause: 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

This cannot be a correct X-Spamcause string, I'm afraid...

no bro it is correct here is the full header

Authentication-Results:mail94c7.megamailservers.com; spf=tempfail smtp.mailfrom=localhost.localdomain
Content-Type:text/html
Date:Wed, 7 May 2025 06:59:20 +0000 (UTC)
Dmarc-Filter:OpenDMARC Filter v1.4.2 mail94c7.megamailservers.com 5476xLl43206121
From:[email protected]
Message-ID:20250507065921.1C1B847E40B@localhost
Mime-Version:1.0
Received:by localhost (Postfix, from userid 0) id 1C1B847E40B; Wed, 7 May 2025 06:59:21 +0000 (UTC)
Return-Path:[email protected]
Subject:SPAM fedex Delivery Waiting
To:[email protected]
X-Envelope-From:[email protected]
X-Origin-Asn:396982
X-Origin-Country:US
X-Rspamd-Result:default: False [6.30 / 6.00]; HFILTER_HELO_5(3.00)[localhost]; DMARC_POLICY_REJECT(2.00)[fedex.com : No valid SPF, No valid DKIM,reject]; MID_RHS_NOT_FQDN(0.50)[]; FORGED_SENDER(0.30)[[email protected],[email protected]]; MIME_HTML_ONLY(0.20)[]; ONCE_RECEIVED(0.20)[]; RCVD_NO_TLS_LAST(0.10)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:~]; RCVD_COUNT_ONE(0.00)[1]; MISSING_XM_UA(0.00)[]; FROM_NEQ_ENVFROM(0.00)[[email protected],[email protected]]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_NO_DN(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; R_SPF_DNSFAIL(0.00)[temporary DNS error]; ASN(0.00)[asn:396982, ipnet:34.139.192.0/20, country:US]; TO_DN_NONE(0.00)[]; NEURAL_SPAM(0.00)[0.836]; ARC_NA(0.00)[]
X-Rspamd-Status:Yes, score=6.30
X-Spam:Yes
X-Spam-Factor:VADE
X-Spam-Flag:YES
X-Vade-Spamcause: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
X-Vade-Spamscore:500
X-Vade-Spamstate:spam:high
X-Whl:LR

Looks like a base64 binary content, running base64 decode returns and ASCII prefix: vade1{…} confirming the version marker.

Sample code:

import base64

# The full Base64-encoded X-Vade-Spamcause header value
spamcause_b64 = (
    "dmFkZTF74xMy5IslKlQPpK1gvXw5/PTzaumShCvGY+Z8PpTElnP2aFtqqcuFX6ZDTCkC36le50IslWryQpehrW79UO5ANoj6u2AsT5l"
    "URJfSGXsNsJ0lkIT32Jn8x63CUQBTMQ5GKnSGt34wQLcz9Iw9Kjv581O22AEbmjD9f0a9g6TfxsvCN3NSzhHsTyxuEX9shIaU/lr8Q"
    "TxpuQ84zb9QPrqD35NGRjrZAcpITiHmsgqpn8tlSLyiv0mRFltixK6H3bN1u61RmRKkaUK8uYjnGjVOapKsoCtt2n5Q/JTo1zlGcrx"
    "dlxhEYSXgVCio5FlkmJLbMhgIMa5GK/fZESAcqEv+cS6Lb1JFqQtZyunHPQzzBKetAhJyVpvPoZP4ja0UMopH4RUvebNS5BuIqI8R"
    "QkIyU4BkgusrQEkoF2Opo3ddLmVo54AqRkRi0ougPmiKJyDStDoQQroWvDjTAGdHu30reJoUlY0K+j2zQ7TDi6ZaEdvWddYkCAfwd"
    "ODtzSfTBYnb18SpRRKBF/fROnvZUI3Fbp2BT45j4NFi5FQtWlC1izWr1eywwX/wa3jky8rdqEJVRd/Mes1IZ0PX9VVttk37fPX0n"
    "mnVOf69Dmb0GUI3Z1E/5K9ClhlMpsm7jr0jASbRtEKIFw+A00dm14N9+KJg4gusfE/LCzFBRBKYFK/Jdw"
)

# Ensure correct padding
spamcause_b64 += "=" * ((4 - len(spamcause_b64) % 4) % 4)

# Decode Base64 to raw bytes
decoded = base64.b64decode(spamcause_b64)

# Build mixed ASCII/hex representation
output = []
for b in decoded:
    if 32 <= b <= 126:  # printable ASCII range
        output.append(chr(b))
    else:
        output.append(f"\\x{b:02x}")

mixed_repr = "".join(output)

# Print the result
print(mixed_repr)

STDOUT/STDERR

vade1{\xe3\x132\xe4\x8b%*T\x0f\xa4\xad`\xbd|9\xfc\xf4\xf3j\xe9\x92\x84+\xc6c\xe6|>\x94\xc4\x96s\xf6h[j\xa9\xcb\x85_\xa6CL)\x02\xdf\xa9^\xe7B,\x95j\xf2B\x97\xa1\xadn\xfdP\xee@6\x88\xfa\xbb`,O\x99TD\x97\xd2\x19{\x0d\xb0\x9d%\x90\x84\xf7\xd8\x99\xfc\xc7\xad\xc2Q\x00S1\x0eF*t\x86\xb7~0@\xb73\xf4\x8c=*;\xf9\xf3S\xb6\xd8\x01\x1b\x9a0\xfd\x7fF\xbd\x83\xa4\xdf\xc6\xcb\xc27sR\xce\x11\xecO,n\x11\x7fl\x84\x86\x94\xfeZ\xfcA<i\xb9\x0f8\xcd\xbfP>\xba\x83\xdf\x93FF:\xd9\x01\xcaHN!\xe6\xb2\x0a\xa9\x9f\xcbeH\xbc\xa2\xbfI\x91\x16[b\xc4\xae\x87\xdd\xb3u\xbb\xadQ\x99\x12\xa4iB\xbc\xb9\x88\xe7\x1a5Nj\x92\xac\xa0+m\xda~P\xfc\x94\xe8\xd79Fr\xbc]\x97\x18Da%\xe0T(\xa8\xe4Yd\x98\x92\xdb2\x18\x081\xaeF+\xf7\xd9\x11 \x1c\xa8K\xfeq.\x8boRE\xa9\x0bY\xca\xe9\xc7=\x0c\xf3\x04\xa7\xad\x02\x12rV\x9b\xcf\xa1\x93\xf8\x8d\xad\x142\x8aG\xe1\x15/y\xb3R\xe4\x1b\x88\xa8\x8f\x11BB2S\x80d\x82\xeb+@I(\x17c\xa9\xa3w].eh\xe7\x80*FDb\xd2\x8b\xa0>h\x8a' \xd2\xb4:\x10B\xba\x16\xbc8\xd3\x00gG\xbb}+x\x9a\x14\x95\x8d\x0a\xfa=\xb3C\xb4\xc3\x8b\xa6Z\x11\xdb\xd6u\xd6$\x08\x07\xf0t\xe0\xed\xcd'\xd3\x05\x89\xdb\xd7\xc4\xa9E\x12\x81\x17\xf7\xd1:{\xd9P\x8d\xc5n\x9d\x81O\x8ec\xe0\xd1b\xe4T-ZP\xb5\x8b5\xab\xd5\xec\xb0\xc1\x7f\xf0kx\xe4\xcb\xca\xdd\xa8BUE\xdf\xccz\xcdHgC\xd7\xf5Um\xb6M\xfb|\xf5\xf4\x9ei\xd59\xfe\xbd\x0ef\xf4\x19B7gQ?\xe4\xafB\x96\x19L\xa6\xc9\xbb\x8e\xbd#\x01&\xd1\xb4B\x88\x17\x0f\x80\xd3Gf\xd7\x83}\xf8\xa2`\xe2\x0b\xac|O\xcb\x0b1AD\x12\x98\x14\xaf\xc9w