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Compliant Solution (Heartbleed)
OpenSSL version 1.0.1g contains the following patch, which guarantees that payload
is within a valid range. The range is limited by the size of the input record.
Code Block | ||||
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int dtls1_process_heartbeat(SSL *s) { unsigned char *p = &s->s3->rrec.data[0], *pl; unsigned short hbtype; unsigned int payload; unsigned int padding = 16; /* Use minimum padding */ /* ... More code ... */ /* Read type and payload length first */ if (1 + 2 + 16 > s->s3->rrec.length) return 0; /* silently discard */ hbtype = *p++; n2s(p, payload); if (1 + 2 + payload + 16 > s->s3->rrec.length) return 0; /* silently discard per RFC 6520 */ pl = p; /* ... More code ... */ if (hbtype == TLS1_HB_REQUEST) { unsigned char *buffer, *bp; int r; /* Allocate memory for the response, size is 1 byte * message type, plus 2 bytes payload length, plus * payload, plus padding */ buffer = OPENSSL_malloc(1 + 2 + payload + padding); bp = buffer; /* Enter response type, length and copy payload */ *bp++ = TLS1_HB_RESPONSE; s2n(payload, bp); memcpy(bp, pl, payload); /* ... More code ... */ } /* ... More code ... */ } |
Risk Assessment
Failing to enforce the limits on integer values can result in a denial-of-service attack, unauthorized disclosure of information, or to run arbitrary code.
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level |
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INT04-C | LowHigh | Probable | High | P2P6 | L3L2 |
Automated Detection
Tool | Version | Checker | Description | ||||||
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CodeSonar |
| (general) | CodeSonar will track the tainted value, along with any limits applied to it, and flag any problems caused by underconstraint. Warnings of a wide range of classes may be triggered, including tainted allocation size, buffer overrun, and division by zero | ||||||
Parasoft C/C++test | 9.5 | BD-SECURITY-INTOVERF, BD-SECURITY-OVERFRD, BD-SECURITY-OVERFWR |
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